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' THERMOFOBMING THREE DIMENSIONAL BET
AND COSTUME ORNAMENT

mom THERMOPLASTIC SHEE/

By Robert G. Dunton, Jr.

This study of the technique of thermoforming
theatrical ornament was prompted by the appearance of
vacuum formed ornament on the theatrical market. Because
the thermoforming process and the ornament produced by
this method seemed to have inherent advantages for stage
use, this study was undertaken to determine if thermo-
formed ornaments could be easily and economically pro-
duced in educational and community theatre scene shops.

\
. In the thermoforming process a suitable plastic

is heated until it becomes soft and pliable. It is then

. formed by mechanical means or by differential air pressure

into the desired shape, normally through the use of a
mold. The simplest type of thermoforming, and the one
most applicable to theatrical work, is that of vacuum
forming.

Vacuum forming is of two types, straight vacuum

forming and drape vacuum forming. In straight vacuum
forming the thermoplastic sheet which has been heated to

its forming temperature is placed over a female mold in

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which small holes have been drilled in order to permit

the evacuation of air from the mold. These holes are ~,
placed in sufficient number to allow the plastic sheet

material to be forced into the details of the mold by ‘
atmospheric pressure. When the air is evacuated from the
mold through the use of a vacuum pump, the plastic is /
immediately formed in the desired shape. fl!

In drape vacuum forming a male mold is used and/"l

the heated sheet is first draped over the mold before , e

vacuum is applied to form the sheet.

After contacting various thermoplastic sheet
suppliers, it was determined that a low cost thermo-
plastic termed Btyrene was a suitable plastic for
thermoformed objects to be used on the stage. This mater-
131 in thicknesses from .0010" to .0020" was found to
be from three to four times cheaper than the thermo-

setting plastic material known as Celsstic used in new

theatre shops. It was determined that the economical
use of the material would. then be directly related to the
cost of suitable equipment for use in forming the
plastic sheets"

After reviewing the literature on the process _ of
thermoforming. many commercial plastics companies were
contacted and their literature reviewed. It was deter-
mined that the most economical commercially produced _
equipment for thermoforming was beyond the reach of lost

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educational and community theatre budgets. Thus the
essential problem involved in the study was to devise
plans for a machine that could be inexpensively built in
the theatre shop.

Utilizing the information gained in the review
of the available literature, a machine capable of per-
forming the techniques of vacuum forming and pressure
forming was designed and constructed. The cost for the
materials needed in the construction of the machine was
approximately $71.00; from five to thirty-four times
cheaper than commercially produced machines.

Operation of the constructed machine revealed
that it was capable of forming many types of theatrical
ornament with sufficient detail for use on the stage.
Several discoveries were made relative to the improve-
ment of the constructed equipment and its cost, but as
their incorporation into the completed machine would
have involved rebuilding the machine ,‘ they were not
incorporated into the completed machine.

The study concludes that thermoforming is a if
technique which presents mam advantages to the theatrical
technician. the chief of these being almost infinite /and
rapid reproduction from one mold. In addition, the I
construction of a suitable machine for thernofcrming is
possible within the budget of most educational or

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community theatres, and the plastic sheet material
required is relatively inexpensive.

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THERMOFOBMING THREE DIMENSIONAL BET
AND COSTUME ORNAMENT
FROM ‘EEERHOPLASTIO SHEET

By
Robert G. Dunton, Jr.

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ATEESIS

Submitted to
Michigan State University ,
in partial fulfillment of the requirements
for the degree of

MASTER OF ARTS

Department of Theatre
1968

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ACKNONIEDGMENTS J
I
This writer wishes to acknowledge his gratitude 1/;
to the members 'of the plastic industry who made this study
possible. Many letters were sent by the author to ‘
companies involved in the plastics industry and replies
were received from almost all those written to; Much
helpful information was contained in the innumerable

brochures, pamphlets, booklets, and books forwarded by

1 these people in response to in many reciuests. The per-

sonal encouragement and good wishes of the writers of
most of these letters were a constant stimulus and in-
spiration to the author in the completion of this study.

The author would be most remiss if he did not
acknowledge a most profound debt to. the person who first
made him aware of the possibilities of theatre and his
own potential in it. Through constant encouragement and . .
constant badgering, Mr." David Pl Karsten has stimulated
this author's curiosity and helped him to expand his
awareness of the theatre and life. It is probable that
without his stimulation this writer would not have begun
the graduate study leading to this thesis. The highest
compliment that can be paid to him is that his influence
has been that of a true teacher}

’ iii

 

 

TABLE OF CONEN’I‘S

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TABIEOFCONTENTS.....‘...‘$‘....

LISTOFCHARTS..'$.......‘..".‘.‘
LIST OF DENIM AND ILLIBMTIOM e e e. ."

CHAP‘EB

I.

II.
III.
IV.

V.

VI.
VII.

APPENDIX .‘.‘.‘............/.

INTRODUCTION ...........
EXPLANATION OF THE PROBLEM . e . .

DESIGNING THE THERMOFOBMING MACHINE

Page
iii

iv

71

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CONSTRUCTION OF THE THERMOFOBMING EQUIPHENT/ 31
THE COST OF THE THERNOFORMING MACHINE .' . .

THE mcrmmn PRODUCT .- . . .
EVALUATION AND OONcLuSIOm . . . ‘ V

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Chart . Page
1. Guides to Selecting the Proper Plastics . . . 13
2. Trouble Shooting Forming . l . .9 8‘ . .' . .' 8' 73

 

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LIST OF DRAWINGS AND IILIBIBATIOM

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straight Vacuum Forming . . . l .'

DrapePorming............
Matched Mold Forming '. i. . . i. . . .
SlipBingPorming . . . . . . . . . .
Plug Assist Vacuum Forming . . . I. .
Plug Assist Pressure Forming . '. . .
Vacuum Snap Back . .i i. . . . . i. . .
Pressure Bubble Immersion Forming 1. .
Trapped Sheet. Contact Heat, Pressure
Pro-Heat Plug Assist Pressure Forming
Vacuum Forming Machine - Side View .
Vacuum Forming Machine - Top View . .
Clamping Frame - Tcp View and Details

View of Thermoforming Machine from Front

Heating Unit as Seen from Above . . .
Clamping Frame in Position on Platen

Household Vacuum Machine . . . . . . ..'

Forming

Clay and. Glued Gauze God Mask Mold . . .
19.? Formed cod Mask Before Trimming and Painting.

1

71

 

CHAPTER I
INTRODUCTION

/
.Although we today tend to believe that the use/

of plastics is a comparatively recent technological ,,’/
development, plastics have been formed since the time of
the Egyptian Empire. It is true that the big' plastics
boom which we are now experiencing dates primarily to
the time of the second. world war when plastics were
develOped to replace materials which were in short
supply, but plastics have been in evidence throughout
history. Thermoforming or heat forming of plastics is
one of the oldest processes for shaping plastics. The
process consists of heating thermoplastic sheets to
their sOftening temperatures and forcing the hot and
flexible sheet material against the surface of a pre-
pared mold by either mechanical. air, or vacuum pressure.
When the heated plastic is held to the shape of the mold
and allowed to cool. the plastic retains the shape and

' the detail of the mold.

In ancient Egypt thermoforming was used to pro-
duce decorative food and beverage containers from
tortise shell. about the oldest known thermoplastic.“

1 .1

/

 

2

The Egyptians found that this translucent, mottled,

and warm yellow material would soften when placed in hot
' water and that in its softened state it could be formed
into a variety of useful and decorative shapes which
they prized very highly.-

Since the time of the Egyptians the process of
thermoforming has not changed greatly and today the
basic principles used by the Egyptians are employed,
although the plastics themselves have changed greatly.
Through modern technolOgy thousands of new plastics
have been invented to fulfill many types of specialized
purposes: More plastics are being developed daily, and
it is said that we have not yet seen the beginning of
the development of the true potential of plastics or of
the plastics industry.

Right now plastics are progressing through what might
be called the Replacement Stage. They have proved

better in thousands of applications than the materials,-

of the past . . . plastics have been chosen because
of superior performance in filling existing needs. ‘

But it is possible to see a new dimension -
call it the Innovation Stage - when plastics will
make possible things that have never been done
before. New shapes, new designs, new applications
stemming from plastic's astonishing and limitless
versatility will permit a fluidity, a grace, a
technological beauty of line and purpose that is
sure to become the hallmarklcf a new way of life
and a new American culture. .

When we consider theitremendous growthof the ._

 

1Dudley-Anderson-Iutzey, '.'.The Society of the
Plagtics Industry," The 1e33, 1933 Tim (May 26, 1968),
p. e.

I

 

3

plastics industry since World War II, the effect of
plastics on our culture and our daily lives, and the
role of plastics in replacing and improving so mam of
the common and specialized products in our society, it
is difficult to understand why plastics have not made a
greater in-road on the technical and design aspects of
the theatre. It has only been in the last five years
that plastics have been produced for use on the stage.
Probably this lack of the use of plastics is the result
of three main factors. The first of these is the lack
of any significant research centers or money for the
development of these centers or research projects in the
field of technical theatre .°' The second has probably been
the thought that plastics are expensive and of avmore
permanent nature than is desired for use on a stage \that
we think of as less permanent than plastics, while the
third is probably related to the comparatively small
purchasing power of the theatre as opposed to the rather
considerable market provided by the television and dis-
play industries. Therefore, those develOpments that
have been made in this field have been directed primarily
to these latter markets. Little thought has been given
by theatre workers to the economical advantages of
plastic in the reproduction of various set and costume
ornaments, or even to the cost of their initial pro-

Va

duction. Plastics ’have mam advantages over other stage

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. materials that make them an excellent material for use

2 cost

on stage. Low cost plastics such as Styrene
approximately .50¢-.70¢ per square yard, while light
weight Celastic3 costs approximately $2.13 per square
yard. This represents a saving of approximately 31.153
to $1.63 per square yard, or enough to buy three to four
times the amount of plastic for the same price as an
equivalent cost amount of Celastic. Nor does this take
into account the cost of solvent for the Celastic.

There is also the advantage of weight. While Celastic
is not a heavy material, plastic is somewhat lighter,
while it is much lighter than new of the other
materials used to produce prOperties and set ornament

on the stage, i.e., wood, plaster, asbestos, plastic
wood, etc..- Plastics. .are also more durable than new of

 

2S tyrene: Polystyrene: A water-white thermoplas-
tic produced from coal tar and petroleum gas. Styrene
is considered to be an ideal material for vacuum forming.
Mam types of modified styrenes are also produced and -.
are used for forming the interiors of most refrigerators.

3Celastic: A waterproof thermosetting plastic
impregnated on fabric which, when immersed in a solvent
such as acetone, methylethyl keton or methyl acetate for
a few seconds immediately becomes self adhesiveand at
this stage is soft and moldable as a wet fabric. Within
a half hour most of the solvent evaporates from the Celas-
tic and it then takes on a stone-like hardness and per-
manently holds its new..shape. Celastic is available in
three standard weights: thin, medium, and heavy. Celastic
Manufacturing Company, 609 Schwler Avenue, learn,
New Jersey 07032.

-»-‘
.—

 

 

5

these substances. A larger advantage of plastic, however,
lies in .the ease of production of plastic pieces. Making
the original mold for a thermoformed product may take as
long as making the finished object by one of the conven-
tional means of production if an actual object that can
be used for a mold is not available, but reproductions
from the mold can be produced in less than a minute. Wood
properties require a great deal of preparation and plaster ~
requires time in molding, mixing the plaster, and settingi‘
Celastic requires the molder to work the material into
all the recesses of the mold. and the solvents are some-
times unpleasant to work with. Plastic molding is rapid,. __
is not unpleasant, requires little or no finishing except
paint, and isusually of a generally higher quality than
any of the above methods of reproduction.

 

 

CHAPTER II
EXPLANATION OF m ROBIEM

The Pm‘pose or'the Study
Assuming that the foregoing principles are true,

the purpose of. this study was to determine whether the
thermoforming of plastics could prove to be an inelgn-
sive means of swiftly and dependably producing stage '\‘
prOperties and set and costume ornament in the non-
professional theatre operating on a low budget. It was
hypothesized that this method could be proved to be a
faster and easier means of production than the methods
currently being used in the non-professional theatre.
Considering the cost factors already presented, it
should be fairly obvious that the cost of the materials
would certainly be cheaper than the materials currently
being used. The deciding factor then becomes the cost
of the machinery to be used in forming the plastic into
the desired shape.

pimitations of the etu_dy
Because the chief factor in determining whether

thermoforming could be proved to be an inexpensive and

6 a

 

 

 

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fast means of producing and reproducing stage prOperties //
and set and costume ornament lies in the cost of construc4
tion of a machine for thermoforming, the study is chiefly
concerned with the development of an effective machine/
for this purpose. The study is limited to the development
of thermoforming equipment that could be ”home made“ by
the theatre technician. Because there are numerous

types of plastics and many methods of finishing them, with
many different processes and types of paint, detailed comp

sideration of these methods was not within the scope of
this study.

a...— a.

pgfinition of terms
ThermOformigg. Thermoforming is a relatively

simple process of heating a plastic sheet, then forming
it to conform to the shape of the product by either a
differential air pressure or via mechanical means. To.“
properly understand thermoforming, one must be familiar
with the large variety of operating techniques used in
the process: These techniques include vacuum forming
(Figure l), drape forming (Figure 2), match mold forming
. (Figure 3), slip ring forming (Figure u), plug assist
evacuum forming (Figure 5), plug assist pressure forming
(Figure 6), vacuum snap-back forming (Figure 7), pressure
bubble immersion forming (also known as billow forming)
(Figure 8), trapped sheet, contact heat, pressure forming“

 

8

(Figure 9). and pro-heat plug assist pressure forming
(Figure 10). The use of the term forming in plastics

technology does not include such operations as molding,
/

casting, or extrusion in which shapes or articles are
made from molding materials or liquids or materials which /

cannot be easily reheated and reformed. '
‘ /

stag-me (pr, ogr’t'i‘e's; Stage properties are consider-7d
to be any decorative or practical element used on the

4"

stage as a part of the. stage picture which is a part of
the design but which is not permanently attached to the
setting, i.e., bottles, lamps, ashtrays, books, pictures.

Set eminent. Set ornaments are considered to be
any decorative pieces which can be affixed to the stage
setting itself. These might include moldings, picture
frames, stair spindles, fireplace moldings or an other
permanently or semi-permanently attached decoration.

Costg’- “emernamen‘t‘st Costume ornaments are deco- .
rative elements such as Jewelry; armour or armour deco-
ration, shoe buckles, masks or an other rigid costume
element which is used to enhance or complete the costume
A design."

'g-on-lipghofessiOnal theatre. The non-professional.
theatre is to be considered as arm theatre group in
which the actors do not consider acting as their sole

means of livelihood. This generally is to be taken to ..
mean the educational and commity theatre organizations.

d'

 

 

9 /

Inexpensive. Inexpensive is to be defined as
less expensive than commercially produced products or
the cost of an article which can be moduced from
materials which are initially less expensive than those
presently being used in the non-professional theatre.
Thermoplastic. A thermoplastic is a plastic or
moldable material which is capable of being repeatedly '
softened by heat and hardened by cooling. Thermoplas-
tics are to be distinguished from THERMOSETTING plastics
which are plastics which undergo a chemical reaction by
the action of heating, catalysts, or ultraviolet light
which lead to a relatively infusible statei Thermosetting
plastics cannot be reheated and reformed as thermoplastics
can. Throughout this paper, the word PLASTICS is used
to indicate thermoplastic materials as distinguished m.
thermosetting plastic materials. 3

Three dimensional. The term three dimensional
is a rather misleading term when it is applied to the
processes of thermoforming. The term generally means an
object whichhas the dimensions of height, width, and
depth or the impression of various distances. Thle
true of the thermofOrmed product also, but the therm .\ ~
formed product does not have the quality of solidity
which we normally associate with the three dimensional
obiect‘.’ Whenthe thermoformed obiect is viewed from the

back, it appears simply as a negative mold of the frent

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view of the object. This is an extremely important
factor when considering the use of the thermoformed ob-
ject on stage, for a stair spindle, for instance, will
look like a solid stair spindle only for 180 degrees or
possibly less. If we look at it from the rear it will
look like a negative image of a stair spindle. This is
generally true for most molded articles unless the
molding is completely encapsulated by the mold. In
order to make an article appear completely solid it
would be necessary to join two halves of the thermo-
formed object, but this is a somewhat difficult task
when we attempt to join surfaces of .000109' - "(025'
together.“ If the object has sqmre corners, two molds
of the object may be used by placing them next to each
other when forming. The two can then be easily folded
E together, but this is impossible if the two objects have
i irregular edges. Flaps may also be built into the pre-
; duct if possible. These then provide more surface area
} for Joining if these flaps are not objectionable in the
- final product? Perhaps the best way to think of the

 

three dimensional possibilities of the thermoformed

object is in terms of has relief. This should be an
important consideration when the designer or theatre
technician centemplates thermoforming an object for

use on the stage:

 

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CHAPTER III
DESIGNING TEE THERMOFQRMING MACHINE

When designing the thermoforming machine the
designer's first consideration must be the use of the
finished product. For work on the stage there are
several important considerations that differ from those
that we would consider in designing a machine to produce
a commercial product} The first of these is the fact
that the object will be viewed by the audience from a
reasonable distance and does not have to stand close
inspection. Therefore, minor imperfections can be
tolerated by the theatre technician. secondly, the
meat important consideration is that the object is
seldom required to duplicate the original but needs
only to look like the original object from the point
of view of the audience." Therefcre, in most situations
we do not have to be concerned with the problem of
sclidity as previously mentioned. This is not to say
that some objects may not have to appear solid, however,
for in the arena situation the audience may be seated on
all sides of the object. Generally these considera-
tions tend to eliminate the necessity for the use of
the more complicated forming techniques such as plug /;
forming. The normal thermofOrming methods that'would/be

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applicable to stage work would then be those of vacuum
forming, blow or pressure forming, and drape vacuum
forming. Probably the most useful of these is that of
drape vacuum forming as it enables the theatre techni-
cian to create a positive or male mold rather than a
negative or female mold. It is usually easier to
create a male mold than a female mold as the molder can
determine exactly what the final product should look
like rather than having to work in reverse. These con-
siderations lead us then to a determination that 'the
best type of machine to design would be one which could
utilize the three techniques mentioned above t drape
vacuum forming, pressure of blow forming, or vacuum
forming. '

The next consideration in the design of a thermo-
forming machine must be the type and size of plastic to x
be used in the machine, this being a determination of
the size of objects that the theatre worker wishes to
form and the amount of money available for the cons truce
tion of the machine. It would be best if the theatre
worker could construct a machine that would be capable
. of forming any size of plastic but this is both difficult
and expensive to accomplish, although it is possible.

A discussion cf the mam types of plastics
available for thermoforming is beyond the limitations of

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of the various types.” ..

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16 \,

Determining the size of the machine is depenp
dent on the size of plastics available. It is best to
determine Which plastics are readily available to you
by contacting your local sheet supplier in advance of
designing the machine. Generally plastic may be pur-
chased either as sheet stock or as roll stock. Roll
stock is usually available in widths based on even
footage although odd widths are available if you order
a sufficient quantity. With roll stock, of course, the
length can be whatever you wish. The same is not
necessarily true of sheet stock, however, but many
various widths are available. Vinyl, for example, is
often.produced in both 20" x 50” and 2l” 1 51" sizes.
Styrene is often produced in.20" z #0", 2“" x Zfl”, and
1&0” x 72" sheetsé It is therefore very important to
first decide the size and type of sheet that you plan
to use before attempting to construct a machine unless
you find it possible to construct a machine that will
adapt to‘varying sizes of plastic sheet. The use of
styrenes, however. is recommended as they are the
cheapest plastics available which are well suited for
vacuum.forming.

. 1..

a m o: m'machine'
There are many types of vacuum forming machines

and theyall have their own distinct advantagesl‘ It

\

__ __ _._‘
R—v jw w—r

 

1?

should be noted here that thispaper has concerned
itself with the construction of a ”machine" as dis-
tinguished from an apparatus. The machine concept is
one in which all the elements necessary tothe vacuum "_
forming process are included in one device. This is not
absolutely necessary for successful vacuum forming to

be accomplished. It is possible to use elements that
are separate from each other. That is, the heater and
the forming table do not have to be a part of the same

'device. For instance, it would be possible to heat the

thermoplastic sheet in an ordinary oven and then trans-
fer it by hand to the , forming table where it would then
be clamped and formed. This, in fact, is the general
procedure used in the construction of outdoor sign
faces. This method makes it easier to adjust the size
of the formed part5 as onlthhe't p half of the clamping
frame is neededyfor the platen or vacuum chamber__ collar ’
can serve as the bottom half of the clamping frame. \l‘hg
exposed portion of the platen can be blocked off with
polyethylene sheet to prevent loss of pressure. However,
this type of production does not lend itself to the most
rapid reproduction of the formed part and was therefore

eliminated from consideration by the writer. Other

5This adjustment of course can only be a
reduction in size from the maximum size of the platen.

 

 

18

types of machine design might be those of: (l) the
upmoving platen or the down moving clamping frame where-
inthe two elements meet by a straight upward or downward
motion.“ This is probably the best type of design, as
it enables the sheet to stretch evenly over the entire
mold while the swing clamping frame stretches unevenly
over the mold as it hits one side of the mold first.
(2) The swinging clamping frame may be one in which the
clamping frame is hinged to the table and is swung from
the heater to the platen or it might be one in which .
arms are used as the hinging device to enable the clamp-
ing frame to descend on.the mold with a movement closer.
to one of ninty degrees. The use of the upward or down?
ward motion of the clamping frame or platen was eliminated
from this design due to the fact that they require more
mechanical elements in order to accomplish this motion / .
and thus they are more complicated and more . expensive/
designs for the theatre worker to construct. The design
on which this researcher decided was one with the hinged
arms which is relatively easy to construct and which
allows the plastic to drape over the mold /from an angle
of approximately sixty degrees, dependent on the height
of the mold.‘ , .

The..heater also can. be brought into positionin
many differentways'.‘ It can.)e swungr over. the sheet; or ‘
it can travel over" the sheet; o. the sheet may be moved

d'
' rt”

 

 

19

under or over the heater. The use of the hinged clamping
frame, however, pretty well dictates the use of a per-
manent heating element over which the clamping frame can
be moved and this is the method used in the design
explained in this paper.

. ~.

General Considerations in the Design .
Because the thermoforming operation is dependent

on heat and the heating of the thermoplastic sheet, all
of the fixtures for the production of the formed part
should be designed with consideration to the conserva-e
tion of wanted heat and the elimination of cooling in-
fluences.’ Beat should not be conducted away from places,
which need to be warm or hot. This means that all sur-
faces which conduct heat should be insulated. for this
purpose asbestos sheet; rubber gasket material, phenol
formaldehyde, or asbestos cement is used. The heater
should be insulated and the clamping frame should be "
insulated from the thermOplas tic sheet. An attempt
should be made to keep the mold and the platen warm and
all air drafts should. be kept from the machine.

. geatigg' : Probably the most difficult con-
sideration in the develoment of a thermoforming machine
is determining the method of heatingta host plastics.

.. become plastic at a temperature arcuui 375degreea1'.‘

If a heating temperature of approximately IIOO to 500 ‘

 

20

degrees F. can be maintained, there 'is little diffi-
culty in rapidly heating the sheet for forming. The
difficult problem, however, is in determining the method
of heating. When working with electricity, the tech- -'
nician will find that there is no clear relationship
betwoen the wattage of a particular heating element

and the amount of its heat output. Many types of heating
elements are available and some are more efficient than
others, but very few are rated in terms of their heat
output. Therefore, any estimate of the wattage output
necessary to heat a sheet of plastic to its forming
temperature can only be taken as a general indication
and cannot be relied upon as an absolute. The best .-
that the technician can do is to proceed on the recom-
mendations of various manufacturers andbe prepared to
add heating elements if necessary. 'Estimates of the
amount of wattage necessary to heat a sheet of thermo-
plastic to its forming temperature range from five. to\‘
tirenty-five watts per square inch. It was found that a\.
watt density of approximately nine watts of infra red
radiation per square inch from375 watt R/llO bulbs was
sufficient for this experiment: That is not to say,
however, that a high watt. density might not be more
desirable. These lamps were operated at maximum
temperatures ." It would be preferable to use more lamps
and operate then at lower temperatures. to obtain maximum

I
d‘

‘ -1

 

 

21

efficiency.

Spotty heating is sometimes a problem when
heating the plastic sheet and this can be overcome} by
shielding the plastic from direct radiation by placing
an absorbing plate betwun the lamps and the plastic.‘

This sheet will then absorb the heat and re-radiate it
at a lower temperature.‘ This technique was not found to
be necessary in connection with the design of the
machine explained here, nor with the forming of any
objects yet formed on the machine.

In order to preferentially heat the sheet in /
areas that you may or may not want to stretch and become/
thinner, it is possible to place a large chicken wire /
.screen under or over the heater on which pieces of //
ordinary screen wire can be placed for preferential heat
treating of the sheet. These pieces will absorb some of
the heat and prevent the plastic from heating evenly. I

Another method of insuring tmiformheating over
the entire surface of the platen sheet is to use stain-
less steel reflectors to radiate the heat uniformly.

The size of the heater should be, slightly_
larger than the maximum forming size. of the clamp. This
is necessary to assure even radiation of heat and to
allow the clamping frame itself to be heated so that it
does not conduct heat away from the plastic sheet. This.
undesirable heat conduction can also be prevented e. '

‘

d”

' 1

22

insulating the clamping frame itself from the plastic
sheet by the use of a gasket.

In.order to control the radiation of heat from
the heater it is also desirable to make the distance of
the heater from the plastic adjustable if possible so
that the heat can.be controlled. H

The best heaters also produce a higher watt denp
sity pattern.around the edges of the sheet and have a
cooler center in order to help overcome cooling side
drafts and heat escape from.the clamping frame.

the clampigg'seeee: The clamping frame is used
to hold the plastic sheet in position for heating and for
forming. It is most important that the clamping frame
be tight on.most types of plastic sheet. if the frame
is not tight on the plastic sheet, it is likely that
the sheet will pull loose from the clamping frame. If

. this happens, the sheet will not form a tight seal with

the platen.and the vacuum.chamber so that the vacuum or
air pressure will escape and the sheet will not form well.
Plastic sheet often.shrinks upon.heating because most
sheet is pressed into shape in the manufacturing process.
If the sheet can.be held tightly in the frame, it‘willA
not shrink from.the edges of the clamping frame. If the
sheet is held in.the clamping frame and upcn.contact'with
the mold does not form'well, the sheet can.be reheated
and reformed. Upon heating it will return to its original

d'

 

 

 

23

shape due to a particular characteristic of plastic
called ”plastic memory.” If. the grip. of the clamping
frame on the. sheet is broken, however, the edges will
not be held and the sheet will not return to its former
shape because of the original pressing process used in
its manufacture. _

In'the construction of the clamping frame,
extruded aluminum is recommended because of its weight
and because it will not tend to conduct the heat away .
from. the sheet as much as aete‘el clamping frame. How-
ever, fabricating aluminum, and. particularly welding
aluminum, would be very difficult in most theatre shops;
A steel clamping frame, if it is adequately insulated, \‘
will be found sufficient for most purposes.

Another desirable feature of the clamping frame
is that it be adjustable in length and width in order to
accomodate different lengths and widths of plastic sheet ‘
stock and make possible different clamping and mold
areas.‘ This, however, is difficult to accomplish
practically in the design of a thermoforming machine as
it also demands that some adjustment be made with the
platen in order for it to form a tight seal with the
clamping frame.

The clwping frame must be adjustable in depth
in order to clamp plastic sheetof different thick-
nesses. The maximum thickness of sheet effectively

4‘

-~‘-_——_._‘.__~ _.4

 

 

fl“-

2“

formed by the thermoforming process is considered to

be 1/1} inch, so the thickness should be variable from

‘0 to 1/1!» inch.

The clamping frame may be lined with a gasket of
sponge rubber, cork, or asbestos to insulate the plastic
sheet from the frame and to better hold the sheet in
the clamping frame itself. If none of these substances
are used, the clamping frame itself may be roughened or /
a bead may bewelded along the edge of the frame to_ /
better hold the sheet tightly in the clamping frame.

* The. ‘klate‘n. The platen is the surface upon/which
the mold is placed or of which it is a part and upon
which the plasticerests whenthe sheet is being formed.
Plywood, masonite, and hardbcard are often used for the
platen and the vacuum chamber. If the platen is large,
it should be constructed of amaterial of a thickness
sufficient to practically eliminate deflection of the
platen. The platen may be reinforced with 2? x M's, if
necessary,’ to eliminate deflection. .When using plywood,
masonite, or regular lumber stock, all the joints should
be -caulked befere assembly. The edges should. not be
glued, however, as the glue will often deflect and _ crack,
thus allowing the vacuum or air pressure to escape. The

outside of the seams can also be scotch taped to further

' protect the platen from leaks. A ridge of some kind

should be built into 'the platen in order to provide a

d“

'\

 

 

25

more efficient seal between the sheet and the platen.-
Air holes in the platen should not be more than 0.01.
inches.
The Surge Tank” and the Pump. Most commercial

machines incorporate a surge tank located in the air-
line between the pump and the platen. The surge tank is
used to contain either the reserve vacuum or the air
pressure necessary to form the plastic sheet after it
has been heated and to provide this pressure rapidly.
Thus, pressure in the surge tank is built up to a point ‘A
greater than actually needed for forming in order to . )
permit rapid forming when, the operator opens the line. /
Ordinarily, 28 pounds ofvacuum pressure per square inch /
are provided with only 14 pounds per square inch normally /
required actually to form the sheet. The surge tank is
usually one and one-half to two times the capacity of _ I
the vacuum chamber. A galvanized hot water tank or cold.
water pressure tank can be used and some commercial
machines even use small oil drums. If a surge tank is i
used, it should allow for a water drain and a vacuum or
pressure guage, whileain water,and oil filters are
desirable accessories. The surge tank should have one-
and-a-half or two-inch pipe connections to connect to
the vacuum chamber. ‘

. The pump may be a rotary pump .or a piston pump.
hilking machines may ‘be used for pumps and. can often be

d“

. I’“.

 

 

26

bought second hand at farm sales. A two stage compressor
used in reverse with the connection made at the intake

is also‘a possibility for use. This would be particu-
larly handy if the theatre had‘paint spraying equipment.
It was fcm'u.-. Mwaver, in this studythatan ordinary

vacuum cleaner supplied more than enough vacuum or ah“.

\

\

pressure necessary to form heated sheet 24".x 27" in size
and from .010 to .on isthmhlesao. .The.-vacum cleaner
can. .be. permanently. .connected-.fc.o .._th.e-vacum chamber. or. a...
one-inchpipe nipple can _be__ins_ta11ed below the valve at
the vacuum chamber. Over this nipple the hose from the
vacuum cleanercan then be easily connected.

m. Valves should be provided within arm's
reach of the operator to control the vacuum or air
pressure as it enters the vacuum chamber so that the
Operator can easily control the forming of the heated
sheet. In a sophisticated machine two valves would be
supplied so that both air pressure and vacuum could be
controlled by the operator. In this case the operator
might use the vacuum valve to control the forming of the
heated sheet and the air pressure valve to help release
the formed sheet from the mold. _ . .

2‘ 'eenm‘ ror men ream '. The type of tooling
used for the thermoforming depends upon (1) the material,
(2) the article to be produced. (3) the number of units
required, and (II) the desired properties of the finished

0'

 

 

2?

. . /
product in terms of thickness, strength, and strain ,'

x /
areas.

Positive molds are preferred as they give sharper
detail, are easier to produce, and produce more normal
stability of the formed part. Rapid changes in sections
of the mold must be avoided because of a/characteristic
of plastic called “notch sensitivity” which simply means
that ninty degree angles and sharp corners crack easily.
Steps and right angles are particularly dangerous in
this connection.

Any plastic sheet material is stretched when it
is formed. Naturally it becomes thinner, and in vacum
forming this thinning will be greatest at the area of ~
the deepest draw. To minimize this reduction in thick-
ness for a given depth of draw, adequate drafté should
be built into the mold to provide a thicker, stronger,
and stiffer formed piece. This will also facilitate the
removal of the formed piece from the mold. Generally
this draft should be from fifteen to thirty degrees,
depending on the depth of draw from one and one-half to
five inches.

Often existing objects can be used for molds .-
When this is done it. is usually. preferable .to examine

6DraftI The angle or taper from the perpendi-
cular of the sides of the mold. - Adequate draft insures
smoother forming and easier removal of the formed part
from the mold. ,,,./-"

28

the object closely to see where the sheet may be

pulled into or around the mold, making it difficult to
remove it from the sheet. This can be corrected by
placing the object in a bed of clay and placing clay in
any recesses which may be classified as undercuts. It
is possible to predict to some degree the action of the
heated sheet on the mold by placing a piece of poly-
ethylene film such as a plastic cleaners bag over the
mold, turning on the vacuum, and observing the action of
the film.

h. 'aterials for Molds. As mentioned above, it is
possible that existing objects may be used as molds when
they are properly used. In addition mam other materials
may be used to construct molds.

When using wood for molds, close grained woods
should be used if a large number of reproductions are to
be made. The wood should be both dry and hard. hahogam,
maple, birch, and plywood are often used.‘ The wood
should be sealed with synthetic resins, high temperature
varnish, or casein. Regular varnish or shellac should
not be used as it will melt on contact with the hot
sheet material. . The side grain of the wood should be
used when possible. Masonite and compressed woods may
also be used.

Ordinary modeling clay may be used for a mold, ‘
but it is suitable for only one forming cycle (rigid-e 25).

d‘

~ “-5

 

 

29

Ceramics are another type of mold material used in the
thermoforming process. These include regular ceramic
materials and special plasters. Ordinary plaster of
Paris is sufficient for several moldings but will not
stand up under numerous reproductions. When these

molds are complex. it is possible to reinforce them with
florists screen, nails, or crumpled masses of chicken
wire placed in the set plaster in order to give strength
to the mass after the plaster has set.

Plastic materials may also be used, but their use
is much more specialized. Briefly, those plastics
generally used are cast phenolic resins, epoxy resins,
and filled polyesters.

Vacuum Hole—é. Vacuum holes in the mold are
necessary to permit the sheet to. be drawn into the
crevices of the mold. The number and size of these
holes to be drilled into the mold will depend upon the
contours of the mold, the type and thickness of the
sheet material} and the desired depth and rate of draw.

The diameter of vacuum holes should range from .0060 to

7.90010 inch. depending on the thickness of the sheet
material used, and whether or not the finished product
will show the image of the vacuum hole. Each man. hole
should be back drilled to within one-eighth inch of the
surface with a large diameter drill.‘ The holes should
usually be spaced two to three inches apart in large

 

 

30

flat areas while holes should be placed possibly as
close as one-quarter inch apart where fine detail is
needed. If desired, slits may be substituted for
vacuum holes. If insufficient detail is obtained in
parts of the product, and there seem to be enough vacum
holes, the vacuum holes should be checked to be. sure
that they are all open before the decision is made to
add more heat to the sheet. If all the holes are open,
then the sheet is probablynot hot enough.

_.-.

 

 

CHAPTER Iv
ccmmuchow or TEE THER‘MOFQ‘IMING EQUIPMENT

.. m... researcher contemplated the construc-
ti on of thermoforming equipment, first consideration
was given to thermoforming techniques that would be most

applicable to stage work. It was decided that an
attempt would be made to design a machine that would
accomplish as mam of the simpler thermoforming tech-
niques as possible 1* This “1...... that an attempt would
be made to construct a machine capable of vacuum forming,
drape vacuum forming, and pressure or blow forming.
This was accomplished by designing a removable platen
that could be removed for vacuum forming or pressure
forming and could be used for drape vacuum forming when
it was in place. Pressure forming can also be accom-
plished with the platen in place .'* In order to keep the
length of the hinged arms from being too long and un-
wieldy,‘ and to keep the machine as compact as possible,
it was decided to make the vacuum chamber capable of
forming to a depth of 5 1/2 inches, or the depth of a
standard piece of 1" x 6"." This depth could be increased,
however, by constructing the vacuum chamber beneath the
surface of the table.“ -
31

A \

; LIBRARY 7

Michigan State
Univers"t 5
i ‘Y r

.. MW"... - H ,‘W‘m'

 

 

 

32

The next consideration was the size of the
clamping frame. This researcher decided on a size of
twenty-four inches by twenty-seven inches because this
is the approximate size or 3.1.". sheet of Cinabex, and
a decision had ”own made to attempt the forming of-
this material. It was later decided that this size ks\
a poor selection as it was difficult to procure styrene ~
or rigid vinyl sheet stock that could be cut to this
size. This researcher would recommend that anyone
attempting to build thermoforming equipment capable of
thermoforming Cinabex build a machine capable of
forming a standard size of plastic such as styrene in
twenty-four by titenty-four inch size and then cut the
Ginsbex if he desires to experiment with forming this
material. Of course, Oinabex is no longer being pro-
duced, and the technician might consider that the size
of the replacement material, said to be called IIaJoroid,
may not be produced in the same dimensions as Ginabex.
This may also influence the selection of a size for the
clamping frame and the machine. '

The hinged type clamping frame with arms
eighteen inches in length was used because it was con-
sidered to be the easiest type of machine to construct.
The arms were made eighteen inches longbecause this
gave a movement as close as possible to ninty degrees ‘
and still made it possible for the platen and the heater

4“

 

 

33

to be placed close together. Determining this length
for any rs...-»_ 2 a it: mostly a trial and error process,
although the designer must realize that in order to get
a smooth and effective movement of the clampirg frame,
the base plate for the arms or the center of their radius
should be approximately one-third or their length

below the platen. Thus, for arms of twenty-four inches,
the platen should be approximately eight inches high, or
eight inches above the base plate of the arms.

The ”Machine. ”Table .' ‘ The"’ machine table was con-
structed of 3/u-inoh plywood four feet wide by six feet
long (Figure 11). Plywood was selected because it ids
standard material in the theatre shop and because it is ‘
easily worked. The table would not have to have been
four feet wide or six feet long, but it was felt that
this would allow space around the machine on which the
theatre worker might wish to place equipment with which
he was working, and because the surface area would make
it possible to alter the relationship of the various
elements if this was found necessary in the construction
of the machine .“ If the theatre worker wished to dupli-
cate the principles used in this design, it would be
possible to construct a machine with table dimensions of
two feet eight inches by five feet. This would permit
the arms of the clamping frame to be mounted on the ..
sides of the table and would eliminate the base plates.‘

d‘

 

3“

This would also perm. t the heating unit to be mounted at
the surface of the table and the vacuum chamber to be
built under the surface of the table, Thus, the machine
would be a little more streamline is its design as
the surface areas would Ni" -. even with the surface of
the machine, It would also eliminate the lumber needed
to frame the heater_arove the table and would reduce the
amount of asbestos needed to insulate the wood from the
heater} \
The seatiggmvnit.’ The heater was constructed in
the shape of a rectangle with interior dimensions of
twenty-three inches by twenty-six inches} This allowed
the heater to be slightly larger than the exposed sheet
in the clamping frame to make it possible to let the
clamping frame sit on the surface of the heater but
still leave a portion.of the clamping frame exposed to -
the heater so that it could be partially heated to help
eliminate the problem of its cooling the sheet by ccnp
ducting the heat away from the plastic sheet, The
heating box was constructed of number thirty gauge
galvanized sheet metal (Figure 15) and although this
material is relatively light, it was found sufficiently
strong to support the infra red lamps and their sockets,
The heater was constructed to a depth.of thirteen.inches

to allow a distance of approximately five inches between

the surface of the bulbs and the exposed thermcplastic

d'

\

 

 

35

sheet. Porcelain receptacles were used and were mounted

on the surface of the sheet metal and wired with number I
fourteen asbestos insulated wire. Note should be taken ,'
here that IT IS ESSENTIAL To 30?le A GROUND WIRE FOR I
THE HEATING UNIT TO ELIMINATE TEE DANGER OP EIECZIBIO

SHOCK. The 375 watt 3/!» infra red lamps were mounted

two and one-quarter inches from the edge of the heating

box and at evenly spaced intervals in order to provide

for a high watt density pattern around the edges of the
thermoplastic sheet. Those in the center of the heater
were spaced approximately seven inches on center (Figure
12). This heating unit was found to be adequate for the
purpose for which it was designed, but the} theatre
technician with more money at his disposal might want

to use more than sixteen lamps on closer/centers to

assure more rapid heating of the sheet. Placing these
bulbs in series with a dimming system would make it
possible for the operator to control the amount of

heat output for the heating of thermoplastic sheet of

am thickness. '

It should be stated here that other types of
heating elements are undoubtedly more effective than the
infra red bulbs used in this design. The bulbs, however,
have the advantage of being easy with which to work. If
the theatre technician wishes to use a different type
of heating element, he will find it difficult to deter-

d‘

 

36

mine the amount of wattage needed in the heating element
to produce the amount of heat required to heat the
plastic sheet to its forming temperature. Additional
experimentation in this field would prove valuable for
anyone wishing to construct a' thermoforming machine,
however. One source of heat that might prove effective
for this purpose might be old broiler units from an
electric oven. Experiments with heating plastic sheet
under the broiler of an ordinary oven have shown that the
broiler unit provides a rapid ‘means of heating the plas-
tic sheet. Broiler units from an old oven would eliminate
the cost of the infra red bulbs and considerably reduce
the cost of the entire machine; However, the size of
the broiler units would then determine the size of the
heater and, to a large extent, the size of the them-
plastic sheet used in the machine; .

Power required to operate the heater was two
circuits of 110 volts rated at twenty-five amperes each.
In a permanent setup, it would be. .best to operate the
machine on 220 volts 3‘ The lamps were wired in four ‘
parallel circuits and then combined into two twenty-
five amp circuits of 110 volts each:

Th. e Clamp ing. Frame. The clamping frame was made
in tw0 pieces which were then hinged together (Figure 13).
The bottom half of the clamping frame was constructed of
one-eighth inch by "One inch angle iron} The material was

I

37

measured to produce an inside diameter of twenty-four
inches by twenty-seven inches. The technician should
be careful when constructing this half of the clampin\g"‘-\
frame to allow some extra space for the thickness of the ‘
angle iron and the fact that the angle iron is slightly
round in the inside corner. Thus, the exterior dimen-
sions of the bottom clamping frame should be close to one-
quarter inch larger all the way around the frame to
allow for this variation. After the sides of the clamp-
ing frame had been laid out on the stock, forty-five
degree pieces were cut out of the stock where the corners
were formed. The stock was then heated and carefully
bent with the aid of a square to assure that all the
corners were square. Then the corners were welded
together and ground flat. These welds are best made if
the edges of the two surfaces to be welded are first
ground to an angle of forty-five “degrees and the weld is
made on the bottom of the frame .

The top part of the frame was constructed of
3/16” by 3/hv" angle iron.‘ The technician should be
careful when forming this part of the clamping frame to
fit the top frame into the bottom clamping fit-axle and
make sure that there is a clearance of approximately
one-eighth inch around the edge between the two frames.‘
When this piece is laid out the technician should care-

fully assume the position of the corners and then

C’

38

simply make a cut into the bottom foot of the angle

iron so that the angle iron can next be heated and easily
bent. The nature of these corners will require that the
technician out. four approximately three-quarter inch
squares and weld. them into the corners of the frame.

All welds on this part of the clamping frame should §\

made on the top portion of this frame to keep the bottom ‘
surface of the frame flats O

In order to construct the adjustable hinge, a
piece of the one-inch angle iron stock was cut approxi-
mately one and three-quarter inches long. A slot
approximately one-half inch long was cut in this piece
starting approximately one-quarter inch from the bottom
of the piece.‘ A position approximately one-third of the
way across the back of the bottom of the clamping frame
was then determined (Figure 13) and a one-quarter inch
threaded hole was made here. A one-quarter inch stove
bolt with a lock washer was then used to bolt the angle
to the back of the bottom clamping frame (Figure 13).
By loosening this bolt the distance betwaen the two
halves of the clamping frame can then be adjusted to
accommodate sheet stock of different thicknesses.

Next a piece of one-inch angle, iron approxi-
mately two inches long was welded at one end to the top
part or the clamping frame. This should be done while
the top clamping frame is resting in the bottom frame,‘

d'

as there 5 be a
which.~ have tr

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both of these on
where they Joint!

39

ap of approximately one-quarter inch

as f: L i when this weld is made in

.ngle level.

) of 0 -~ ‘ “ inch bar stock was
ted pi .ssure that it would
and d! . iaen.it was adJusted. The

was bet sq to an.angle of forty-five

would : Eve the upper part of the
be raise' *4 far as possible when th;\m\\
n order ake it easy to insert the

to slightly larger than one-quarter
five-sixteenths inch was drilled through

-inch angles at the center of the area

no that a one-quarter inch bolt could

be inserted here «a which the two sections of the

018mP1n8 frame could hinge (Figure 13)}

Next, two pieces of one-inch angle iron were

'welded opposite the hinges on the bottom part of the

clamping frame, making sure that they did not extend

below the bottom surface of the frame; These were also

imcunted slightly below the surface of the frame to make

it possible to exert more clamping pressure than if the

angle was flush to the surface} Next, two pieces of one-
inch angle ironwwere welded parallel to the bottom of the
top part or the frame so that theywould line up with the

4

S

1+0

pieces welded on the bottom part of the grams (Figure
13). Again these should be welded while/”the top part
of the clamping frame is resting in the ‘/bottom part of
the frame as a section between the angle and the frame
will again have to be filled when it is welded in order
to allow the piece to be parallel to the bottom part of
the clamping frame when it'is completed. Now it is
possible to clamp the two halves of the clamping frame
together in the front opposite the two hinges by utiliz-
ing twa spring clamps. For this purpose two battery
clips were used. These proved to work very ~well and
were inexpensive to purchase (Figure 16).

Finally, four three-eighth inch nuts were welded
to the sides of the bottom frame to permit the swinging
arms to be connected to the bottom clamping frame with
three-eighths inch bolts (Figure 19).

After this welding has been completed, it will
be found that the heat of welding has shrunk and twisted
the metal slightly. In order to make the surfaces flat
again, so that they will meet squarely, it will be
necessary to bend the metal frames so that they corres-
pond to each other. This is a —trial and error process
and can best beaccomplished by setting the frames on
blocks of 2" x 4" and dumping on the frame until by \\
trial and error, and by fitting the two pieces together\\~
to check them, the two pieces are made to fit as flush

‘-

#1

as possible. Minor variations will be compensated for
by the asbestos strips which should next be cut and
glued to the two Joining surfaces of the clamping frame
(Figure 13). These can be adhered to the surfaces of
the clamping frame with Permatex cement. The asbestos
will not only compensate for the minor variations in
the frame but'will also help to hold the thermoplastic
sheet to the frame by providing a rough surface which
will resist the shrinking pressures of the thermo- .
plastic sheet and at the same time insulate the theme.“
plastic sheet from the cold clamping frame. /

Because of the variations in the surface of the
clamping frame caused .by the welding of the [various
pieces to the frame, it is recommended that the clamping
frame be constructed with three hinges rather than two,
and that the hinges be placed one on each corner and one
in the middle of the rear of the clamping frame, and
that the angle used for clamping be placed opposite
{those on the front of the clamping frame. This would
better help to overcome the variation in the slu‘faces
of the frame, as it appears that this variation occurs
mostly in- the corners of the clamping frame.‘

sang“ ~ing Arms. After the clamping frame has
been completed,- the arms can be constructed. These were
constructed of 1/2" x 3/16? flat stock, eighteen inches
longs A hole drilled at either end of these 7/16 inch

‘-

(+2

in diameter will permit the arms to pivot on three-
eighths inch bolts placed through them into the nuts on
the frame (Figure 13) and through the base plates con-
structed of two-inch by one-quarter inch angle iron
(Figlu'e 16). The bolts should be inserted into the

nuts on the clamping frame with washers in betmen to
(allow the arms to swing more freely. The base plates
were simply drilled to accomodate the bolts for the
swing arms and were then drilled on the opposite face

so that screws could be inserted to attach the plates

to the top of the machine table.‘ Again, if the machine
were constructed with a width of two feet eight inches,
these plates would be unnecessary and the arms could be
bolted directly to the sides of the machine table. This
might also prove to be a little more smooth in the opera-
tion of the frame as the sides of the table would also
serve to guide the arms and prevent some of the side
sway inherent in this design. It was found that mount-
ing the base plates of the two rear arms approximately /
1/16” behind the position where they would normally be ‘
placed, determined by placing the frame on the vacuum
chamber collar and extending the arms rearward after
bolting them to the clamping frame, a tight seal between
the rear portion of the frame and the chamber could be
assm‘ed when the operator placed downward pressure on
the handle of the frame and created an adequate seal on

d"

“3

the front portion.

Although not really necessary, it was found
easier to operate the machine if the clamping frame was
.counterweighted. This was accomplished by tapping a
one-quarter inch hole Just below the three-eighths inch
bolt at the top of the swing arms. Into this was
threaded a one-quarter inch eye bolt. The nut on the
bolt was used to lock the eye into place against the
arm (Figure 13). To the' two eye bolts on either side of
the frame were attached a short length of rope . A
running pulley was placed on this rope and the pulley
was connected to another length of rcpe which ran to an
overhead pulley and a series of pulleys which led to the
rear of the machine where a bucket of sand was used to
counterweight the weight of the clamping frame.

Eh) I e Platen and vacuum Chamber. The vacuum
chamber was constructed of one-inch by six-inch white
pine (Figure 11) and was constructed to fit inside the
clamping frame with approximately one-eighth inch
clearance all the way around (Figure 16). The sides
were caulked with ordinary caulking compound and then
put together with one and one-half inch screws . The i”
chamber was then screwed to the table of the machine "
after this Joint was also caulked. A hole was then out /
in the middle of the chamber area to accomodate a one and _‘
one-half inch pipe floor flange. The floor flange was /

.T' A /

/
/

//

m. \_‘
.\‘

screwed to the bottom of the table after caulking com-
pound was placed between it and the table surface to
insure a tight seal. A one and one-half inch floor
flange was used because it was the only size available
when the machine was built, and adapters then had to be
used to use one and one-quarter inch pipe connections to
the vacuum cleaner.

The platen itself was constructed of one-quarter
inch hardboard because some of this material was on hand.
1/56 inch diameter holes were drilled in this material
at one inch intervals (Figure 12). This was an attempt
to construct a universal platen so that any obJect used
for a mold could simply be placed on top of the platen
and so there would be a sufficient number of vacuum
holes close enough to the edges of any obJect so a
separate platen would not have to be constructed for
every mold used in the vacuum forming process. It
would probably be possible and more desirable to place
these holes at one-half inch intervals to enable a
larger number of holes to be lined up along the edges of
any mold used. These holes were back drilled with a
one-quarter inch drill to assure smooth passage of air
to or from the surface of the platen. It was found
necessary to reinforce the platen with two pieces of
2" x 2" placed one-third of the distance across the

‘\

length of the platen. In order to provide air and vacuus

‘

“5

channels to the surface of the platen, one-quarter inch
holes were drilled through the 2" x 2" 's wherever the
holes on the platen came above them. The/so channels
then permitted the differential air pressure to flow
through these holes to the surface of the platen.

Finally, the platen was screwed to the surface
of the vacuum chamber after first caulking the surface
of the vacuum chamber. The 2" x 2"‘3 were screwed to
the sides of the vacuum chamber with one and one-half
inchscrews.‘ The use of screws makes it possible to.
remove the platen so that the vacuum chamber can be used
for straight vacuum forming. If the air supply is
reversed, it can. be seen that the machine can also be
used for blow or pressure forming. Thus, the machine
has the potential for accomplishing all of the forming
techniques for which it was designed.

Next a collar of 1" x 3" white pine was placed
around “the vacuum chamber (Figure 13) to provide a
ridge on which the clamping frame could rest (Figm'e
16). This was placed three-eighths inch below the
surface of the platen so that when the clamping frame
rested on the surface of this collar, it would be
approximately one-quarter of an inch below the surface
of the chamhr and an effective seal would be created‘\\

betwaen the sheet and the vacuum chamber. It was \~

‘\

necessary to drill ens-half inch holes. into this collar

1+6

over the screws which attached the platen to the sides ;/

of the vacuum chamber in order to permit the removal of j
the platen.

The. Vacuum Soflurgg. Probably the most expensive /
part of any thermoforming machine would be the vacuum or /
air som‘ce. Because of this, one obJective of this at

was to determine whether a device as simple and inexperi-
sive as a vacuum cleaner could be used. It was fo

that a household vacuum cleaner was more than adequate

for the requirements of this machine, and, in fact, it

was found desirable to reduce the amount of vacuum

provided by the machine in some instances./ In order to
construct a more permanent machine, a one and one-quarter
inch nipple was brazed to the intake and the output of

the vacuum cleaner so that it could be attached to a
coupling used to connect it to the vacuum chamber (Figure
17). It is necessary in this design to manually '
disconnect the vacuum cleaner and turn it around and
reconnect it to switch from vacuum to air pressure or.

vice versa. It would be possible to connect the vacuum
cleaner with a series of pipe and valves so that two

valves could be manipulated to control the air or vacuum
pressure, but this might prove to be a much more expen—
sive way of handling the problem. Of course, the idea

of the use of the vacuum cleaner was to determine whether ,\

, a household vacuum" cleaner could be used to provide the

i

h?

vacuum and air pressure necessary for the operation of
a thermoforming machine of this size. A regular vacuum
cleaner would not have to be converted in the manner
described above in order to operate the thermoforming
machine. The vacuum cleaner hose could be slipped over
a! one-inch nipple to use the vacuum cleaner to provide
vacuum or air pressure to the thermoforming machine.‘
The vacuum cleaner could then also be normally used in
its regular capacity. If the theatre'technioian desired
to permanently attach a vacuum cleaner to the machine,

a used vacuum cleaner could probably be purchased for a

relatively 10" price at a vacuum cleaner sales center.

CHAPTER V
THE COST OF THE TEEBMOFORMING MACHINE

The total cost of the thermoforming machine as
designed was approximately $71.00.: This figure does
not include incidental materials like screws and nails
that the theatre technician could be expected to have
on hand, nor does it incluie the vacuum cleaner, as it
is assumed that he will have access to a vacuum cleaner.
This figure is well below the cost of a commercial
machine to accomplish the same thermoforming techniques.
The most inexpensive thermoforming machine discovered
by this researcher that can be compared to this design
has a forming area of twelve inches by eighteen inches
. and is sold for $295.00.? Machines forming twenty-four
inch by twenty-four inch areas run up to and above
$2350.00.48 These machines are certainly more sophisti-
cated and desirable than the machine described in this
study, but their sophistication is not necessary for
most theatrical requirements. It .is possible that (by

 

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using different materials,'such as oven broiler units
and other scrap materials that would normally be found
in.the theatre shop, a thermoforming machine based on
the principles set forth in this paper could be built

at a cost to the theatre well below 350.00. The
following analysis shows that an inexpensive machine can
be constructed in accordance with the definition listed
in the limitations of this paper.

    
  

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CHAPTER v:
THE THERMOFORMED PRODUCT

There are new ways to finish the thermoformed
product, both before and after it has been molded, and
before and after it has been trimmed from the plastic
sheet. There are also many ways to utilize the thermo-
formed product in the completed stage design. This area,
however, is not within the limitations of this paper. It
should be sufficient to say that most plastics can be
finished with the casein paints used for general stage
work, although many other types of paint can be used. /In
this connection, the designer might find that samples--
tics have two distinct surfaces, i.e., a matte surface
and a glossy surface, and he will probably find it
‘ desirable to form his product with the matte " side on the
outside, as this will give him a better surface for the
adhesion of paint.‘ Thermoformed materials can be easily
attached to set pieces through the use or ordinary maskim
tape. Many other types of paints and dyes can be used
and different techniques are used with all of these
materials. Other means may be used in finishing the
thermoformed sheet also, methods such as reverse engrav- ; .
ing, back painting, etching and silk screening are used.

52

53

These methods and the various materials used in the
finishing of thermoformed products are largely dependent
upon the types of plastic used in the forming process.
Therefore, this area of the thermoforming process would
‘ benefit most from a complete and detailed study of the
qualities of various plastic materials that could be
used, and the methods of finishing them, thus providing
the theatre worker with ideas for the creative use of
plastics as a part of the total stage design.

The example of the thermoformed product in this
study is a design created by Alan N. Armstrong, II, for
the God mask required in ".1. 3.," written by Archibald
hacLeish.‘ ' An existing mask of gauze impregnated with
glue was used as the basic mold. Clay and heavy twins
were then added to this to complete the design (Figure
18). It was found. that it was necessary to reinforce
the back of the original mask-with clay, styrofoam, and
blocks of wood as the mask collapsed when subJected to
the vacuum presstu'e. After this was done, the mask was
easily formed in .0020 Styrene (Figure 19). The finished
mask, painted with casein paint and shellaoed, was used
in the 1968 Michigan State University Summer Theatre
Festival production of “J. B.”

This mask could have been produced in many
different ways. It could have been molded in clay and
then formed in Celastic, paper macho, fiberglass, gauze

51b

and glue, or glue and felt. All of‘these methods,
however, would have required that the theatrical worker
mechanically form the materials over the mold. This
would have required much more time and also more
materials than were required by the thermoforming pro-
cess. After the basic mold was created, only one minute
was required for the actual forming of the mask, and this
was accomplished without the use of..irritating solvents,
or messy glues. Because this mask was molded partly in
modeling clay, it was possible to form only one obJect
from the mold, but if the mold had been created in a
more substantial material, many copies of the original
could have been produced at the rate of one a minute.

It would also have been possible to create a more sub-
stantial mold by using the initial product as a negative
mold to produce a final positive” plaster mold which could
have been used to mold further reproductions.

The cost of the material used to produce this\».._
mask was approximately thirty cents . Mass produced
ornament, commercially produced, costs approximately ten
times this amount, although it does have the advantage
of not requiring the designer to produce his own mold
or have his own thermoforming machine. To have taken
this design to a commercial plastics forming compaw and
request that they form the me]: would have been even

more expensive, probably prohibitively so.” It would

8

55

also have been less convenient and may have required
more time of the designer than that required by the use
of his own machine.

The distinct advantages of using this process,
then, were a saving of time in production, not of the
mold necessarily, but of the completed product, a cost
less than the use of Celastic and of most other conven-
tional materials, and ease of production. The mask
produced was also of high quality and conformed to the
exact wishes of the designer who made the mold himself
rather than turn to, the available products of a comer-
oial producer.

Thermoforming plastic is not the answer to all
of the designer's ornamentation problems. It cannot,
for instance, compete in cost with the production of
paper macho ornament unless the designer's time is taken
into account as a cost factor.’ It is also subJect to the
three dimensional limitations explained in the definitio/n

‘ /
of that term in the second chapter (pages 9-10). It

/

does, however, provide a rapid and relatively inexpenSive
method of producing high quality ornament for! use on the

stage." /

I!

CHAPTER VII
EVALUATION AND CONCLIB 10m

It has been shown that an inexpensive machine
for the thermoforming of plastic stage properties can
be constructed in the theatre shop. It has also been
shown that the thermoforming process is not only capable
of almost indefinite reproduction or a formed part, but
that that part which has been reproduced is produced
more cheaply and with less effort than through most of
the methods presently available to theatre workers. In
the last few years several companies have begun produc-
tion of plastic scenic and costume ornaments. It is
the opinion of this researcher that these products may
be too expensive for the community or university theatre
to purchase. It should not be difficult for the theatre
technician to see the advantages that his own thermo-
forming machine would give him.* He could produce repro-
ductions of his own design at reasonable cost with a
minimum amount of effort. In this regard it is signifi-
cant to note that the thermoforming process has advance ‘
possibilities far beyond its purely ornamental ones.-
C.R.S‘.¥ Television in New York is currently producing
vacuum formed scenic panels of approximately four feet

56 A ;

57

by twelve feet in size. These panels are formed in the
shape of various textured wall surfaces, such as brick,
stone, shingle, and clapboard. The thermoformed sheets
are then stapled to a rigid frame such as is normally
used in regular flat construction. The machine used by
C.B.S. to accomplish this cost them approximately 31.500039
It is entirely possible that the theatre technician could
build a machine capable of producing panels of this size
much more inexpensively. It might even be possible that
a machine of this size could be built in the threatre
shop for under $500.00.- This is not to say that it would
be as refined as the machine used by the Columbia Broad-
casting System, nor would it be capable of the variety

of operations which that machine is,’ but it could cer-
tainly closely approach the capability of it in regard

to most of its completed products.

This paper has consentrated also on the replace-
ment value of the plastics and the thermoformed product
as a substitute for the present methods of ornament con-
struction and has not attempted to ’delve into the creative
use of plastics on the stage. This is a sadly neglected
area in the field of technical theatre .‘ Some work has
been done in the television, and movie, and display
industries, but little has been done " in the legitimate

 

‘9A1fred E.‘ Landolph, Purchasing Agent, Columbia
Broadcasting System, Personal letter (February 6, 1968) .‘

f

58

theatre. Consider for a moment the various qualities

of the following ideas: acrylic plastics have the ability
to "pipe light.” In the sign industry sheets of acrylic
plastics have been etched' with letters and the rest of
the surface of the signs have then been opaqued. By
placing a light at the edge of the sheet, and by inn};
ducing color medium betwaen the light and the sheet, the

\

§

color of the letters is made to change as the color
medium is changed.”- what are the possibilities here of
building flats of acrylic sheet and then changing their
color by this process? Or how about flats made of
acrylic plastic having wallpaper patterns engraved into
them so that the color of the wall paper pattern could
be made to change from moment to moment, or act to act?
Recently a refrigerator with a plastic door was
introduced. The door appears to be a coppertone door
until the housewife touches the handle of the refri-
gerator."- At this point the light in the refrigerator
goes on and the housewife can— see through the door into
the refrigerator to see what kinds of foods are there
before opening the door. What might the possibilities
be here for the use of plastic on the stage as a type of
scrim? There are many other design possibilities in the
field of plastics. Recently plastics coated with sponge
rubber flocking and foil finishes have been introduced
which hold promise for use on the stage. Plastics are

59

available in may colors in addition to transparent and
translucent materials. These hold much promise for use
on the stage. Certainly the effect of light on trans-
parent plastics could be extremely interesting and might
prove to. produce new effects which are not obtainable

on the stage by any other means. Again, of course, the
question arises as to who will do this research. This "
type of research is expensive. When the researcher d/oes
' not know exactly what he will encounter, he must often
work by the trial and error method. The cost to one
person involved in this type of research is almost pro-
hibitive. This study was found to be quite expensive
because of several false starts. If this study has
accomplished anything, the hope is that it will whet the
curiosity of the theatre technician and show him that
there are opportunities in the field of plastics. At the.
same time this researcher hopes that it will show that
there is a potential here to be developed and encourage
organizations to spend the money to promote this type. of.-
research in the theatre .“~ This researcher believes that
the academic theatre is often too concerned with histori-
cal research in order to determine past theatrical
practices. Consequently, the future possibilities of
the theatre are often neglected. It is true that we
built on the past, but that does not mean that we

60

have to live in it or conform to it. The theatre of

tomorrow which we hear discussed today will not be
built yesterday,” but today and tomorrow. It is hoped
that this paper can serve to point out where modern
technology can be applied to theatrical practices in
order to help stimulate the creative development of

the theatre .

APPENDIX

62

FIGURE 1. STRAIGHT'VACUUM FORMING.
The plastic sheet is clamped and heated. .A vacuum
beneath the sheet (A) then causes atmospheric pressure
to push the sheet down into the mold. As the plastic
contacts the mold (B), it cools. Areas of the sheet
reaching the mold last are thinnest (0).

FIGURE 2. DBAPE FORMING.
The plastic sheet is clamped and heated (A), then
drawn over the mold or by forcing the mold into the
sheet. When.the mold has been forced into the sheet
and a seal created (B), vacuum applied beneath the
mold forces the sheet over the male mold. By draping
the sheet over the mold you.first drOp the sheet
touching the mold on the mold surface and it remains
close to the original thickness of the sheet. Side
walls are formed from the material draped between.the-
tcp edges of the mold and the bottom seal area at
the base; Final wall thickness distribution is
shown.in the drawing (c).

FIGURE 3. MATCHED MOLD FORMING. .
Matched molds of wood, metal, plasters, qioxy, etc.
can be used to press the sheet to shape. The heated
sheet may be clamped over the female die (A) or can
be draped over the mold force. As the mold closes, //
it forms the sheet (B). Mold.vents allow trapped air
to escape. Clearance between the mold force and cavi-
ty of the mold depends upon tolerances required in
the part. Excellent reproduction of mold detail and
dimensional accuracy can.be obtained from.matched mold
forming, including lettering and grained surfaces.
Material distribution of the formed part (0) will
depend upon the shape of the two forms. -

FIGURE h. SLIP RING FORMING. ,’ ,
Heated plastic sheet is placed across the female die?
As the press closes (A) pressure pads clamp the sheet
lightly to allow it to slip under controlled tension
as the mold force is pushed into the sheet. Air
beneath the sheet is vented (B) to avoid creating a
backpressure. lAs the mold finally closes, the pres-
sure pads exert maximum holding pressure against the
sheet retaining enough of the sheet to avoid losing
the final formed shape. ‘Vacuum or air pressure then
-can be applied (6) beneath the sheet to form it over
the mold force or pull it into the cavity. However,
neither air nor vacuum is needed as long as the mat-
ing mold sections fit properly. uniform wall thick-
neww as illustrated in.drawing (D) depends upon
proper control of sheet slippage as well as upcn.the
specific geometry of the part involved.

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FIGURE 5." PLUG ASSIST VACUUM FORMING:

After the plastic sheet is heated and sealed across
the mold cavity (A) a plug, shaped roughly as the

mold cavity but smaller, is plunged into the plastic ‘\

sheet and pre-stretches the material. When.the plug
platen has reached its closed position (B) a vacuum
is drawn on the mold cavity to complete formation of
the sheet. ‘Wall thickness can be varied by changing

the shape of the plub (C). Areas of the plug touching
the sheet first create thicker areas due to the chill-

ing effect. Consequently, plug design is a most imp
portant factor in determining Just what the geometry
of the formed part being produced by this technique
will look like.

FIGURE 6. PLUG ASSIST PRESSURE FORMING.

Plug assist pressure forming is similar to plug assist

vacuum forming (A and B), except that as the plug
enters the sheet air under the sheet is vented to the
atmosphere. ‘When the plug completesits stroke and
seals the mold, air pressure is applied from the plug
side. The air pressure can enter through the plug or
from behind the plug (0).; Those areas of the sheet

first making contact‘withithetair- e chilled sooner..

In some cases, heated air is re ~red. Plug temp

peratures are also important.:* lug assist pressure '
forming can be controlled to produce uniform.material
déstribution.over the entire formed part as shown in

Home 7. VACUUM SNAP BACK FORMING.

-.

After the plastic sheet is heated and sealed over the
top of the female vacuum box (A) a vacuum applied at

the bottom of the vacuum box pulls the plastic material
into a concave shape. The latter can be controlled by
turning vacuum on.and off to maintain a constant shape
in the sheet. 'When the plastic has been.pre-stretched,

the male plug enters the sheet (B) and a vacuum is
drawn.through the male plug. 'Vacuum beneath the
sheet is vented to the atmosphere or light air pres-

sure is applied in place of the vacuum; External deep

draws (D) can be obtained from the vacuum snap back.
pressure for forming items like luggage, auto parts:

FIGURE. 8. PBBSSUBB BUBBLE ImasIou Somme.

Once the heated plastic sheet is clamped and sealed
across the pressure box (A) controlled air pressure

applied under the sheet causes a larfi; bubble to form:

The sheet pre-stretches about 35 to percent. 'When
it is preformed to the desired height (B) a plug is
forced into it (C) while air pressure beneath remains
constant. ‘When.the male plug closes on the pressure

, box, higher air pressure beneath the sheet and'vacuun

beneath the mold creates a uniform.drawr

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66

FIGIRE 9. TRAPPED SHEET, CONTACT HEAT, PRESSURE FORMING.
Plastic sheet is inserted between the mold cavity and
a hot blow plate. The plate (A), flat and porous,
allows air to be blown throw n its face. The mold
cavity seals sheet against t... hot plate. Air pres-
sure applied from the female old beneath the sheet
blows the sheet totally again. :5 the contact hot
plate. A vacuum (B) also can b" ‘ “'m on 11.... hot
plate. After predetermined heating, ~ "at
is ready for forming.‘ Applied air pressuis tn... - -:h
the hot plate forms the sheet into the female mold.
Venting (C) can be used on the cpposite side. Steel
knives can be inserted in the molds for sealing.
After forming (D) additional closing pressure can
be exerted.

FIGURE 10. PRE-IEAT PLIB ASSIST PRESSURE FORMING.
Boll plastic sheet is fed through top and bottom pre-
heaters. (A) The hot sheet then is indexed beWeen
the top and bottom rams of a forming press where the
parts are plug-assisted into female molds and formed
by air pressure and vacuum. Next the rams open (B).
Dm‘ing the forming process additional plastic sheet
has been heating in the pre-heating section (C).
Now new, pre-heated material is indexed into the
forming ram area (D) and the entire thermoforming
cycle as described above is repeated.

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71

FIGIBE lh.‘ View of Thermoforming Machine from Front.
FIGURE 152‘ Heating Unit as Seen from Above:

FIGURE 16. Clamping Frame in Position on Platen.‘
FIGURE 1? .‘ Household Vacuum Machine.

FIGURE 18. clay and Glued gauze God Mask Mold.
FIGIBE 19. Formed God Mask Before Trimming and Painting.“-

72

 

 

 

 

 

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73

CHART II

TROUBLE SHOOTING FORMING-

 

 

 

 

 

 

 

 

Poor design

...0

TROUBLE REASON SUGGESTED CURE
BLUSHING Molded too cold Increase heating time
.. Exceeding yield point Increase molding speed
WEBBING Molding too hot Shorten.heating cycle
'Vacuum too slow Increase area and
Layout too close number of holes
. .- USe drape grid assist
SHEET scones Heat Input/Min. Use lower heat
BUT NOT Too Rapid Longer Cycle
PLNSTIC . ~ Heat both sides.
MOLD RELEASE Draft insufficient Increase and/or
DIFFICULT OR Undercuts polish mold
IMPOSSIBHE Mold.”Roush' shrunk. Eliminate or, if minor
on.mold use air assist
- Polish and lubricate
mold
Change to female mold.
, if possible ‘
' Cut down.dwell time
in.mcld
\.
PLASTIC ‘ Overheating Extend Cycle and
BUBBLES Moisture lower heat
Entrapped.Air Preheat sheet sloWIy
Check for moisture in
air if blow molding
Correct venting or add
vacuum.hcles.
CRACKING Stress concentrated. Increase radius of

all angles
Redwork design.- add
reinforcements

“Increase heat

TROUBLE . ,

WARPING

EXCESSIVE
SHRINKAGE
OF SHEET

71+

CHART II (Continued)
REASON '

S tress
Improper cooling

Poor design

Stress in sheet

SWGES‘EED CURE

Try slower mold en-
try and more heat

Allow to cool on mold
longer

Eliminate long flat
surfaces

Shorten time under
heat and elevate
temperature

Change sheet layout

Generalme.iu_angz_alszmzsaams 0' f, at

Thermopgstic Sheet (Lawrence, Massachusetts, 19 7 ,
Po . .

75

SOURCES OF MATERIALS ’POR THERMOFORMING

ADHESIVES :

CLAMPS!

HEATING

Bostik

B. B. Chemical Division

United Shoe Machinery
Cambridge, Massachusetts 02139

Cadillac Plastic and Chemical Company
1511 Second Avenue
Detroit, Michigan #8203

Adjustable Clamp Company
417 North Ashland Avenue
Chicago, Illinois 60622

De-Sta-Co Corporation
350 Midland Avenue
Detroit, Michigan #8203

Knape and Vogt Manufacturing Company
658 Richmond Avenue '
Grand Rapids, Michigan #95016

Knu-Vise Products Division
Lapeer Manufacturing Comparw '
3056 Davison Road

Lapeer, Michigan "BM-I6

EQUIPMENT:

A.A.A. Plastic Equipment Company -
Post Office Box 11510

2509 West Berry ‘

Fort Worth, Texas 76110

Edwin L. Wiegand Company
7613 Thomas Boulevard
Pittsburgh, Pennsylvania 15208

Faratron ' ~

Subsidiary of Thermatrcn-Wilcox-Gibbe
214 West 39th Street

New York, New York 10018

76

General Electric Company

Large Lamp Department /
Nela Park /
Cleveland 12, Ohio /

Honeywell Incorporated
Aparatus Controls Division
2747 Fourth Avenue South
Minneapolis, Minnesota 55h08

Hotwatt Incorporated
128 Maple Street
Danvers, Massachusetts 01923

COMMERCIAL THERMOFORMING MACHINES.

A.A.A. Plastic Equipment Company, Incorporated
Post Office Box 11512

2215 West Berry .

Fort Worth, Texas 76110

Abbott Machinery Division
Dynamics Corporation cf.America
Post Office Box 1083

Scranton, Pennsylvania 18501

American Remolit Corporation
79 MadisonHAvenue
New York, New York 10016

AtlasJVac-Machine Division
Koehler-Dayton Incorporated;
”01 Leo Street

Dayton, Ohio h5h0h

.AutOJVac Company Incorporated
Post Office Box 557
Tabor City, North Carolina 28h63

Brown.Machine Company
Beavertcn, Michigan

Comet Industries Incorporated
1320 North York Road
Bensenville, Illinois 60106

DieAcro Division

Houdaille Industries Incorporated
300 Eighth Avenue

Lake City, Minnesota 550nl

77

Plasti-Vac Incorporated

1091 North Davidson Street

Post Office Box 4453

Charlotte, North Carolina 28205

FINISHING OF PLASTICS:

PAINTS:
The Glidden Company _
Graphic Arts and Sign Finishes Division
11001 Madison Avenue
Cleveland, Ohio M102

Keystone Refining Company, Incorporated
#821-31 Garden Street
Philadelphia, Pennsylvania 19137

Lilly Varnish Company
666 South California Street
Indianapolis, Indiana #6225

United States Paint, Lacduer and Chemical Company
Singleton at 21st Street
St. Louis, Missouri 63103

EXTURING: '
Roll, Die and Mold Decorators Incorporated
801 North Meridian Road
Youngstown, Ohio M509

WELDING OF PLASTIC: -
Kamweld Products Compam, Incorporated
7162 Providence Highway
Norwocd, Massachusetts 02062

PLASTICS SUPPLIERS .'

American Hoescht-Ccrporation
Hostachem Division

270 Sheffield Street
Mountainside, New Jersey 07091

American Renclit Corporation
79 Madison Avenue
New York, New York 10016 _

Cadillac Plastic and Chemical Compam
15111 Second Avenue
Detroit, Michigan #8203

78

Cafiitol Plastics Company
Fisher Building
Detroit, Michigan #8203

Cast Optics Corporation
21“ South Newman Street
Hackensack, New Jersey 07602

Commercial Plastics and Supply Corporation
630 Broadway
New York, New York 10012

Diamond Alkali Company
300 Union Commerce Building
Cleveland, Ohio M115

E. I. DuPont DeNemours and Company
Plastics Department
Wilmington, Delaware

The Dow Chemical Company
Plastics Department

Molding and Extrustion Sales
Midland, Michigan #86140

Eastman Chemical Products, Incorporated
Kingsport, Tennessee 376 62

Foster Grant Company, Incorporated
Leominster, Massachusetts

General Electric Company
Chemical Materials Department
Pittsfield, Massachusetts

The General Tire and Rubber Company
Chemical Plastics Division »
1708 Englewood Avenue

Akron, Ohio #4309

Gilman Brothers Company

Gilman, Connecticut
(Suppliers of foamed, flocked, glittered am
foil covered sheet)

-- ‘. Monsanto Company

800 North Lindbergh Boulevard
St. Louis, Missouri 63166

PLASTIC .

79

Purex Corporation
Post Office Box 958
Woodside Drive
Richmond, Indiana

Rohm and Haas Company
Independence Mall West
Philadelphia, Pennsylvania 19105

Seilon Incorporated
Plastics Division
Newcomerstown, Ohio #3832 _

Shell Chemical Company
Synthetic Rubber Division
113 West 52nd Street

New York, New York 10009

Sweedlow Incorporated
Department.E 1.

12605 Beach Boulevard

Garden Grove, California 926%

THEATRE SUPPLIES 8

Alcone Company Incorporated
32 West 20th Street

New York, New York
(Negoccll and Celastic)

Celastic Manufacturing Compaw
609 Schuyler Avenue »
Kearny, New Jersey 07032

(

Columbia Broadcasting System, Incorporated

Alfred E.‘ Landolph, Purchasing Agent

52 West 52nd Street
New York, New York 10019
(Plastic Scenery)

Costume Armour Incorporated
#29 West 53rd Street
New York, New York 10019

Tobins Lake Studios

2650 Seven. Mile Road

South Lyon, Michigan #8178
(Easy-Ornament)

 

{LIBRART’TT

Michigan State (
..i JCI‘Sit f
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_~1- "9"7‘?”'-:-~ .1. II

 

Pg“... v «5.. 1...-.. ._ _-. 44

80

Plabras Armour
Giesen Company
38 9th Street
St. Peter/St. Paul, Minnesota 55102

Polymer Corporation Limited
Sarnia, Ontario, Canada
(Plastic Rubber sheet stock)
(Available from
Northwestern Costume House Incorporated
3203 North Highway 100
Minneapolis, Minnesota 551422 .

MATERIALS FOR HOLDS:

Cerro Sales Corporation ‘\
300 Park Avenue
New York, New York 10022
(Low Melting Point Alloys)

The Decorators Supply Corporation

3610-3612 South Mor an Street

Chicago; Illinois 0609

(Plaster ornaments that could be used for molds)

Kish Industries,’ Incorporated
1301 Turner Street

Landins, Michigan #8909
(Epoxy resins)

Tech Consolidated Incorporated
20 Dickey Street

Derry, New Hampshire 03038 .
(Electroformed molds and dies)

Union Carbide Corporation
Plastics Division

270 Park Avenue

New York, New York 10017
(Epoxy resins)

United States Gypsum Compaw
101 South Wacker Drive
Chicago, Illinois 60606
(Gypsum plasters and cements)

TOOLS Pm WORKING “I'm PLASTICS:

The Cutawl Corporation
Bethel, Connecticut 06801

81

Lennon and Snoap
2618 Thrcnwood S.W.
Grand.Rapids, Michigan #9509

VACUUM PUMPS:

Central Scientific Company
2600 South Kostner
Chicago, Illinois 60623

The Stansi Scientific Division
Fisher Scientific Company
1231 North Honors Street
Chicago, Illinois 60622

Worthington Corporation
h26'Worthington.Avenue
Harrison, New Jersey

BIBLIOGRAPHY

Books

Butzko, Robert L. Plastic Sheet Formigg . New York:
Reinhold Publishing Corporation, 1958.

Cherry, Raymond. General Plastics: Pro acts and Pro-
cedures. Bloomington, Illinois: M ghtand
McKnight Publishing Company, 1967.

Cook J. Gordon. The Miracle 9; Plastics. New York:
' Dial Press':'_ 19

Kaminsky, S. J., andWilliams, J. A. H_s_._____ndbook f__o_r .
Welding and Fabricating Thermoplastic ”Materials.
Noaood, Massachusetts: Kamweld Products Company,
19 .

McConnell, Williamx. "Thermoforming," Moder Plasgics
Enc clc dia. New York: McGraw H , Incorporated,
196%"

. Directory of Manufacturers, Processors, a_n__d
Suppliers; Trademarks _a___nd Brand Names; Trade
Associations ggg Technical Societies. New York:
Modern PIEstics, 1 .

 

Newkirk, Louis v.4, Hewitt, Coleman, and Zutter, LaVada.
Adventures with Plastics. Neonrk: D.C. Heath
and Company, 1947.

Swanson, Robert S. Plastics Technology . Bloomington,
Illinois: McKnight and McKnight, 1965. /

Newspapers . /

Daley-Anderson-Iutzey. The Society of the Plastics /
Industry. “Plastics Will C Your World,”
The New _Y___ork T__i___mes, XII (May 2 , 1968), 3.

Catalogues .
Cadillac Plastic and Chemical Company. M:

82 /

33

Catalog____ and Lice L_i__st:.' Detroit: 1967.

Plastic Products Company of Utah. Wp'mclegale Qaglog.‘
Salt Lake City: 1967.

Pamphlets

Cadillac. Plastic and Chemical Company. H. 12.. Work with
Plexiglas. Detroit.

Di-Acro... How to Form Plastic Sheet Materials with L116

 

Dow Chemical Company. Decoratipg 921! Plastiog. Midland,
Michigan, 1967.

Dow Chemical Company. Formipgfl of Lar e Area Deep gym
Part____s_. Midland, Michigan,T%I9.-— "“‘“'“’

E. I. DuPont DeNe‘mours and Company. Hand lipg and Fa__b_r__i- ‘
cation 2;; Acrylic Sheets. Wilmington, Delaware.

General Tire, Chemical/Plastics Division. Topgh-Colorffl
Boltaron: _A Manual 2; Low Pressure Formipg__ of /
/

Thermo-Plastic _S______heet. Lawrence, Massachusetts.
Masson, Donald (ed.). The Story_ of the Plastics Ind____u_s_- /
try. Prepared under the direction of The Public /

Relations Committee, The Society of the Plastics
Industry, Incorporated. New-York: The John B. //

Watkins Company, 1966.

Monsanto Company. PPoducti'on Techni'g'ues‘ for Vacuum
Formipg Thermoplastic Shee 3.. Production Infor-

mation Bulletin No. 1092. St. Louis, Missouri,

1967:
Nadelberg, By}: (William M. Pry). The Star 9;; Po
styrene. Los Angeles, Cali-I‘B'fnia: __P 8 ice

International, Incorporated, 1963. .1

Rohm and Haas. Patrioation or leri ias . Philadelphia:
Rohm and Haas Company, 9 .‘ ,

Ll

..
i“ ,

LIBRARY

Michigan State :
Universit‘ f,
[if

mwvup- —-r- w '

{,‘—_.__.__‘.. . .

81+

Unpublished Material

Education Committee, North Texas Section of the Society
of Plastics Engineers, Incorporated. “Plastics
References, Manuals, Texts, Trade Publications
and Publishers of Books on Plastics.“ Fort /
Worth, Texas, 1966. (Mimeographed.) . /

Other Sources

Alfred E. Landolph, Pm'chasing Agent, Columbia Broad-
cagtazing System. Personal Letter.‘ February 6,‘
19 . /

/

MICHI AN STATE UNIVERSITY LIBRARIES

HITHIIIII m mm H

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