AN APPROACH TO THE SELECTION OF MACHQNE TOOLS ThuitforflnmofM.S. | meme“ STATE uumww . Erik Hugo Rucim 1957 ".‘flES’S LIBRARY Michigan Static University NOV 0 4:. 49 7 rH‘;g15,;’-‘,\ OH'HL L-Hu'v‘LKSiTY FELIX“ 385:1. E. \Ci.‘ Kain. m ET. 3 I AN APPROACH TO THE SELECTION OF MACHINE TOOLS by' Erik Hugo Rucins AN ABSTRACT Submitted to the College of Engineering Michigan ‘State University of Agriculture and Applied Science in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Mechanical Engineering 1957 0 Approved: CZ:EZE:%Z:%§Z;;é;;’*’ ($7 ERIK HUGO RUCINS ABSTRACT The invention of the wheel is considered one of the greatest milestones in man's cultural development. Since this invention machines have played an increasingly greater role in making man's physical tasks easier and more efficient. Today machines are used to build other machines. These we call machine tools. When a manufacturer is faced with the problem of selecting the machine tool best suited for a particular task, he faces a staggering problem of variables to be resolved. In this paper the following approach to the problem of machine tool selection is proposed: Determine the related factors between the machine tool and work piece. Classify each factor into smaller groups. Examine each group and collect related information. All this information is then coded and punched on cards. When the need arises for a specific machine tool one simply sorts the coded cards to select the machine or machines best adapted to the work at hand. Metal removal tools are used as a model, and the code used is four digit; the first two digits designating the production characteristics, and the last two digits designating construction characteristics of the machine tool. When selecting a machine tool for any type of application the following factors are considered: ERIK HUGO RUCINS . ABSTRACT 1. Surface to be machined Work piece dimensions Work piece material Tolerances to be held Surface funish Work piece holding The number of pieces to be made Selection of cutting tools \OCD‘flmU'lkUOh) Relative cost H 0 Personnel factors [—4 H Floor Space 12. Weight The next step is the grouping and coding of the factors in such a manner that they can be placed on punched cards. In this example the machine sorted International Business Machine (IBM) card is used. In coding the differ- ent factors a direct code is used. In this system a single hole represents a single idea. When the different characteristics have been coded from the data furnished by the manufacturer a punched card is prepared. One card is prepared for each machine tool. Machine tools can be selected by analyzing the part by characteristics then sorting and selecting the machine tool cards. ERIK HUGO RUCINS ABSTRACT The same approach can also be used for other equip- ment selection problems, such as: Forming equipment Processing equipment Welding equipment, etc. The greatest advantage of this system is that the technique eliminates the possibility of overlooking a process not well known to the engineer, or at least one he did not know was adaptable to his current problem. An advantage of this system is that a great number of cards can be sorted in a short time. This can be done by any office worker, and an engineering decision is not necessary until the very end. This eliminates time wasted by engineers searching for their information in numerous catalogs. This system like any catalog must be kept up to date or it will become obsolete. This can be considered as a disadvantage. The system is also at a disadvantage if the selection process has to be stopped while finding the proper cutting tool material for the material machined. By adapting a computer to this system the human effort could be completely eliminated, since computations and comparisons would be done by a machine. AN APPROACH '10 THE SELECTION OF MACHINE TOOLS by Erik Hugo Rucins A THESIS Submitted to the College of Engineering Michigan State University of Agriculture and Applied Science in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Mechanical Engineering 1957 ACKNOULEDGMENT The author wishes to express his sincere thanks to Mr. James M. Apple, under whose lofty inspiration, constant supervision, and unfailing interest this problem was under- taken and the results achieved. He also is greatly indebted to Professor Fritz B. Harris for his kind guidance and valuable help in preparin this thesis. TABLE OF CONTENTS CHAPTER I. INTRODUCTION. . . . . . . . . . . . II. CLASSIFICATION OF MACHINE TOOLS . . . . . III. DETMIINING FACTORS IN MACHINE TOOL SELECTION. IV. GROWING AND CODING m FACTORS . . . . . V. PREPARATION 01' PUNCED CARDS . . . . . . VI. APPLICATION '01" TH METHOD . . . . . . . .VII. CONCLUSIONS. . . . . . . . . . . . APPENDICES Appendix A--Classification of Machine Tools. . . Appendix Bun-Cutting Speeds and Feeds for Standard T0018 0 O O O O I O O O O D BIBLIOGRAPHY O O O O O O O O 0 O O O O O 7 49 58 63 67 71 84 9O LIST OF TABLES TABLE PAGE I. Operations and Machines for Machining Flat Surfaces. . . . . . . . . . . . 9 II. Operations and Machines for Machining External Cylindrical Surfaces. . . . . . . . 9 III. Operations and Machines for Machining Internal Cylindrical Surfaces. . . . . . . . 10 IV. Tolerances on Drilled Holes . . . . . . 114 V. Tolerances on Reamed Holes . . . . . . 14 VI. Machining Operations (Tolerances) . . . . 15 VII. Range of Roughness of Industrial Finishes . 17 VIII. Properties of Tool Materials. . . . . . 29 IX. Surface Speeds for Single Point Tools FEM . 31 X. IMachinability Depends on Microstructure . . 33 XI. Relative Cost to Produce . . . . . . . 47 XII. Inventory Form . . . . . . . . . . 59 LIST OF FIGURES Figures Page 1. Range of Surface Finishes Microinches RMS. . 21 2. Keysort Cards . . . . . . . . . . . 50 3. 1m Card. . . . . . . . . . . . . 52 1+. m! Card for Sunstrand Automatic Lathe. .' . 61 5. Example Put 9 o o s e s s o c o s 63 LIST OF GRAPES Graph Page 1. Break Even Method. . . . o . . . . . 25 2. Tool Life versus Cutting Speed . . . . . 41 3. Gilbert.and TruckenéMiller meograph . . . 42 A. Metal Cutting Chart . . . . . . . . . 44 5. ‘Metal Cutting Chart [Example]. . . . . . 65 CHAPTER I INTRODUCTION Man‘s daily life for ages past has found him doing certain routine tasks that he strove to make easier or Jobs beyond his powers. The greatest problems were the handling of heavy weights, fighting of fires, pressing of wine, and oil and watering fields . As an individual, man.at first did everything by main strength and was quite ineffective when it came to doing things in a big way. .During the course of time he began.to search for the easier ways of doing Jobs, or he took more complicated projects. He invented devices to do.a better Job--more quickly and effectively. -From the history of man’s development, we are able to follow his searches and his accomplishments. It is possible to indicate the general pattern of how the basic components of mechanismsand machines were first put into use. From.individual machine designs, machine tool groups used for similar types of work were developed. Machine tool builders develOped new machines for different phases of the work piece. Thus, the machine tool builders became one of the greatest parts of industry. The machine tools available are so numerous that the engi- neers and company managers face a problem in selecting the correct machine for each Job. Selection of the proper machine is subject to many influences. A proper selection must be based on many variable factors such as, size of work piece, work piece material, surface finish, work piece holding. In any event, all related and influencing factors must be interpreted in terms of costs and results. As the proper selection of the basic machine influ- ences the degree of efficiency that can be achieved by any production.process, so does the specification of the tooling to be used with it. Investigation of tooling in terms of costs and pro- duction achieved, can uncover other areas of profit poten- tial over the years. Selection of the right machine tools to meet each shop and product condition is often quite difficult when more than one type of machine may be employed for a specific purpose. It is with the idea of simplifying this task that the approach described in the following pages was developed. CHAPTER II CLASSIFICATION OF MACHINE TOOLS Selection of machine tools is not a simple task because of the great number of variable factors that are involved. To simplify this problem all of the machine tool characteristics will be studied. Besides this all of the related factors between machine tools and work piece will be determined. All of the factors will be classified in several small groups, and each group will be examined and the related information collected. Then each group will be subdivided into smaller parts and coded. Coding will be done in such a way that the infOrmation may be placed on punched cards. The first step in this approach will be classifi- cation of machine tools. There are many different types of machine tools and production equipment so to simplify the approach only the metal removal machine tools will he discussed. Metal removal machine tools will further be called simply'machine tools. They will be grouped into various groups and for each.machine tool a code number will be assigned. various large manufacturers have established their own.machine tool classification charts. In this project as a source for classification.the Directory oijetal- working'Machinery, published by the Department oijefense, is used. Certain basic factors establish the "nature of the work" that is performed by machine tools, and machines vary in design and construction because of these factors. Therefore, machine tools may be classified by productionr characteristics and subdivided by construction.character- istics. This classification helps to clarify the reasons for their individual adaptability for specific kinds of work. In classification.of machine tools four digit code will be used. The first two digits designate the production characteristic as: Boring Machine -~ 11 .Broaching Machine ~~ 12 Planers -» 18 The next two digits designate construction characteristics as: Boring Machine horizontal table type -- 11-11 Boring Hachine vertical standard -« 11-21 Planer} Rotary —e 18-70 CLASSIFICATION OF MACHINE TOOLS Boring_Maghines 11-10 11-20 11- 0 11— 0 11-50 11-60 Horizontal Boring Drilling and Milling Machines vertical Boring and Turning Mills Including Vertical Turret Lathes Precision Boring Machines Jig Boring Machines Boring Machines Miscellaneous Boring Machine, Horizontal, Center Drive Broaching Machines 12-10 12-20 12-20 12- 0 12-50 12-90 Horizontal, Internal and Combination Internal and SurfaceIMachines-~Hydraulic Vertical Internal Machines-«Hydraulic Vertical Surface-eHydraulic Rotary Surface-«Hydraulic Broaching Machine, Mechanical Drive Broaching Machines (Miscellaneous) Drilling Machines 13-10 13-28 1 - 13.30 13-50 13-60 13-80 13-90 Sensitive Bench Sensitive Floor and Pedestal Upright Type Radial MUItiple Spindle (Cluster of Spindles Drives.From One Central Power Unit) Automatic Deep Hole Drilling Drilling Machines, Miscellaneous Gear.Cutting_and.rinishinngachines 14-10 lfi-2O 1 - 0 14-30 14-50 14-50 14-70 Gear Bobbing Machines Gear Shapers Gear Cutters, Form Milling Type Bevel Gear Cutters, Net Including Planer Type Gear Cutters, Planer Type AMiscellaneous Gear Cutting Machines Gear Tooth Finishing Machines Grindinngaghines 15-10 15-20 15-30 15-40 .External Cylindrical Interna1»Grinders Surface Grinders, Rotary Table Type Surface Grinders, Reciprocating Type Grindinngachines (continued) 15-50 15-60 15-70 15-80 15-90 Lathes 16-10 16-20 16-30 16-40 16-50 16- 6O 16-g0 16-90 Disk Grinding Machines Thread Grinding Machines and Form Tool and Cutter Grinders Bench, Floor and Snag Grinders Grinding Machines Miscellaneous Bench Floor Heavy Duty, Engine Turret Lathes'Not Including Automatic Chucking Chucking Automatic, Between Centers Chucking Automatic Screw Machines, Bar Boring and Combination Boring and Turning Lathes Lathes Miscellaneous MillinggMachines 17-10 17-20 17-30 17-40 17-50 17-60 17-70 17-80 Bench Type and Hand Millers Knee Type, Except Bench Type Ram Type, Swivel Head Bed Type Planer Type Profiling Machines and Duplicators Die Sinking Machines Thread Milling Machines Planers 18-10 18-20 18-30 Double Housing Openside Plate Planers Miscellaneous Machine Tools 19-10 19-00 19-30 19-40 19-50 19-60 19-70 19-80 19-90 Shapers and Slotters, Not In Honing and Lapping Machines, Honing and Lappin.g Polishing and Buffing Machines Sawing and Cut Off Machines Contour Sawing and Filing Machines Tapping Machines Threading Machines, Not Including Thread Cr%.l ing or Milling Rifle Working Machines, Not Including Deep Hole Drilling Machine Tools, cludir.g Cear Shapers N0 t 143.81 11d: .Lq-log .L- ;,'f’) Miscellaneous (Not Elsewhere Classified) [A more complete list of Machine Tool Classification is shown in Appendix A.] CHAPTER III DETEHMINING FACTORS IN MACHINE TOOL SELECTION The machine tools alone cannot determine the best manufacturing results. The relationship between machine tools and work piece is very important as this relation- ship will include very many variables to be concerned with in machine tool selection. The problem.of selecting a proper machine tool for any type of work may be aided by examining the work piece and other related factors. The following factors should be considered: 1. Surface to be machined 2. Uork piece dimensions 3. Hark piece material . Tolerances to be held 5. Surface finish 6. Work piece holding 7. The number of pieces to be made 8. Selection of cutting tools 9. Relative cost 10. Personnel factors llo Floor space 12. .Height Each of these factors will be discussed in detail. The purpose of the following discussion is to indicate the magnitude of the problem.mislead in making decisions re- garding each of these factors. Following this discussion a technique for simplifying the selection of an appropriate machine tool, in spite of this tremendous problem, will be shown. 1. Surfacegtq_be Machined One of the first points which is established when considering the machine type for a given work piece, is the shape of the work, and the surface or surfaces to be machined. The surfaces to be machined may be identified as follows: Flat External Cylindrical Internal Cylindrical External Taper Internal Taper Contour Key Hays Slots Threads - O.D. "‘ 10D. - Pipe - Nipple Knurling Multiple Gear Special li’ll‘tllli If?! The following representative Tables I, II, and III, will show the scope of operations and machines for producing Flat, External Cylindrical, and Internal Cylindrical surfaces. Right from the beginning it can be seen that this is one of the most difficult parts of machine tool selection. It is very difficult for any one person to become acquainted with all of the possibilities, as it is very hard to meno- rize all of the factors and all of the variations. There- fore, it is hoped, that the punched card system, to be discussed in this project will eliiinate all of these difficulties. TABLE I OPERATIONS AND’MACHINES FOR MACHINING FLAT SURFACES L535 Ire uently Seldom Used v oPeration Most Commonly Used Use Shaping Horiz-Shaper Vert. Shaper Planing Planer Milling Milling Lathe (with ,Machine attachments) Facing_ Lathe Boring Mill Broaching Broaching Machine Grinding Surface Lathe (with Grinders attachments) TABLE II OPERATIONS AND MACHINES FOR MACHINENG EXTERNAL CYLIXDRICAL SURFACES LESS Frequently Seldom Used ——_..—-- __.___ -..— _-- _..__...__. .___ __.._ Most Commonly Operation Used Used Turning Lathe Boring Mill Vertical Shaper Milling Machine Cylindrical Lathe (with Grinding Grinder attachments) 10 TABLE III OPERATIONS AND MACHINES FOR MACHINING INTERNAL CYLINDRICAL SURFACES Operation. Most Commonly Less Freguently Seldom Used Used use Drilling Drill Press Lathe .Milling Machme Boring Mill Horiz.Boring Machine Boring Lathe ,Milling Boring Mill Machine Horiz.Boring Drill Press Mill Beaming Lathe Milling Drill Press Machine Boring Mill Horiz.Boring Mbchine Grinding Cylindrical Lathe (with Grinder attachments) Broaching Broaching Machine The most commonly used maciine tools for each operation will be used in classification and coding. The less frequently and seldmm used machine tools will be con- sidered for emergency use only. 2; Kerk Piece Dimensions The work piece dimensions are important in machine tool selection because they determine the size of the machine tool° From the work piece dimensions the general ll idea of the size of machines, stroke, swing, distance be- tween centers, etc. can be determined. The work piece dimensions for each group will be subdivided into smaller groups and coded in order to be put on punched cards. Dimension subdividing and coding will be discussed later. Work piece dimensions are of basic importance be- cause machine clearances and working stroke requirements are involved. Critical machine clearances on the engine lathe, turret lathe, and single spindle autenatics, for example, are usually defined by the swing-over bed ways, carriage, or cross slides. Herk piece swing for single spindle automatics and all multiple spindle automatics is usually limited to an area roughly equal to the diameter of standard equipment work-holding devices. Engine lathes and tool slide lathes working strokes are usually more flexible than those in single spindle automatics and multiple spindle automatics. That is, the cross slide units may be positioned and fed longitudinally under power along the machine bed or cross-wise according to work piece requirements. The cross slides of single and multiple spindle automatics, are normally fixed in longitudinal position and fed under power in a crosswise direction only. 12 Critical machine clearances on shapers, planers, and milling machines are the length and width of work piece, and the height of work piece that can pass under the tool heads. In drilling and boring operations the depth of hole is the determining dimension. In.broaching the length of surface machined deter- mines the stroke of machine. Before selecting any machine tool work piece dimen~ sions should be considered, such as: l‘ Length - Uidth Height -' O'Do - I.D. - Depth of Hole - Spherical Diameter 3. HOrk liecejMaterial Parts are machined from.every conceivable material and frequently the chemical analysis of the part determines to some extent, the best type of machining equipment and cutting tool. Identification and classification of work piece material is very important because cutting tool and work piece material determines the relation between cutting speed, feed, depth of cut, cubic inches of material removed, and machine horsepower. JBy identification and classification of work piece material is meant placing the components into such 13 categories as the following: Wrought iron Low-carbon steel Stainless steel Standard SAE steels beginning with SAE 1015 or SAE 1020 Cast steel Cast irona-unmodified and uncontrolled . Cast iron-«modified as semi~steel or controlled as Mechanite and Limite - Cast iron~~specia1, as white or chilled iron Malleable iron - Non—ferrous materials, such as aluminum, magnesium.and their alloys, copper and its alloys and plastics llllt I I Identifying and classifying the work piece material correctly makes possible the selection of the surface speed that also will give best results in terms of cutter life and performance. 4. Tolerances Production parts do not have invariable dimensions. For this reason, the purpose of dimensional specification is to limit or restrict size variations. Hhere the per- missible amount of variation is specified, all parts included within the bounds of the limits are regarded as useable parts. The basic dimension as specified by the designer is the theoretically perfect dimensions, and the allowable deviations therefrom are indicated on the engi- neering blueprint. As a convenience to both the design __‘_A A 1H. A. Fromelt, '"How to Set-Up Carbide Milling Job," American Machinist, April 24, 1947. l4 engineer and production personnel, the amount of permissible variation is given as the tolerance and is defined as the range of variation within which an item.is useable. Dimen- sions are generally shown on drawings with tolerances. Depending on material stock size and kind of mach- ining operations performed, different variations in basic dimensions can be obtained. Tables IV, V, and VI will show the variations from.basic dimensions for representative machining operations. TABLE IV TOLERANCES ON'DRILLID»HOLES* . A . Drill Size Range Tolerance Smallest Largest Plus . .Minus .013??? .042(#58) .00 .002 .043 57 M9 .00 .002 0935 42 .1560 .005 .002 1562 .2656 .006 .002 .266 (H) .4219 .007 .002 .4375 .6094 .008 .002 .625 E50 .009 .002 .g656 437 .009 .003 594 2. 000 .010 .003 *G.M. Engineering Standards TABLE V TOLERANCES ON REAMED-HOLES To 1/4" 1551. +j.0001 to + .0004 Over l/4"~l"incl.+ .0001 to + .0005 + .0002 to + .0006 Over 1‘ TABLE VI MACHINING OPERATIONS* 15 renames:- VARIATIONS mm Mm DIMENSIONS .251 .501 .751 1.001 2.001 Diameter or Stock Size to I? to to to to to . .250 .5001 .750 1.000 2.000 4.000 Drilling . Bee "Limits In Tolerances" ' Band 2.0005 20005 20010 20010 20020 20030 ““m‘“ Mum. 20010 20010 20010 +.001o 20020 20030 . -.0015 -.0020 Tux-nine 20010 20010 20010 20020 20030 Dorm 20010 20010 20015 20020 20030 Internal Game 25 in Drilling, Roaming or Boring “Mme External rot-min; 20015 20020 20020 20025 20025 20030 1183;; External $121113! 20010. 20010 20010 20010 "20015 20020 Shoulder Location. Turning? 20050 20050 20050 20050 20050 20050 Shoulder Location. rormtgl' 20015 20015 20015 20015 20015 20015 straddle Mining 20020 20020 20020 20020 20020 20020 Milli slotting (Width) 20015 20015 20020 20020 20020 2.0025 (8mm '3,” Face Milling 20020 20020 20020 20020 20020 2.0020 End Milling (Blot Widths) 20020 20025 20025 20025 ' Hollow Milling 20050 20000 2.0100 8mm" Internal ' 20005 20005 20005 20005 20010 2.0015 Surface (Thickness) 20010 20010 20010 20015 20015 m H +.0005 +.0005 +.0005_ +.0005 +.0005 +.0010 Pgi‘fnt’" “m ° . -.0000 -.0000 -.0000 -.0000 -.0000 -.0000 Shoulder Depth 20010 20010 20010 20010 20010 20010 L Hobbit-2 20005 20010 20010 20010 20015 20020 Honing +.0005 +.0006 +.0005 +.0005 +.0008 +.0010 -.0000 -.0000 -.0000 -.0000 -.0000 -.0000 Shaping (Gear) 20005 20010 20010 20010 20015 20020 Burnishlns , 20005 20005 20005 20005 20000 20010 Cylindrical (External) 41.0000' +.0000 +.OOOO +.0000 +.0000 +.0000 . -.0005 -.0005 -.0005 -.0005 -.0005 -.0005 Cylindrical (Internal) +.0005 +.0005 +.0005 +.0005 +.0005 -.0000 -.0000 -.0000 -.0000 -.0000 Grlnding - Centerless +.0000 +.0000 +.OOOO +.0000 +.0000 +.0000 -.0005 -.0005 -.0005 -.0005 -.0005 -.0005 +.0000 +.0000 +.OOOO +.0000 +.0000 +.OOOO 3“““9 (kamss) -.0020 -.0020 -.0030 -.0030 -.0040 -.0050 *G.M. Drafting Standards l6 5. Surface Finish The proper functioning of a machined part is to a large extent dependent on the quality of its surface. In its broader aspect, the term "surface quality" includes not only the dimensional qualities of the surface, but also the material, hardness, color, luster, and metallurgical struc- ture. The dimensional quality, having to do with the finer irregularities of the surface is known as the "roughness" of the surface. The urgent need for high production and low cost has developed techniques in which roughness control is of proven importance, not only on the finished piece but on the intermediate finishes as well. The surface of hard materials is composed of a pattern of irregularities which may be the surface produced by casting, extruding, or flame cutting, or by a mechanical process such as shaping, sand blasting, turning or grinding. The pattern of surface irregularities is usually very complex, as each of the various factors in the finishing maehine adds its own con- tribution to the finished surface. (‘ Roughness Range-~Surfaces produced by a given type of finishing operation vary widely in their roughness. This variation.is due partly to the obvious control over roughness that is at the oper- ator's disposal (such as the shape of the tool an- the feed of a lathe cut), partly due to factors beyond the operator's control (variation in hardness of material or changes in grinding wheels), and largely to differences in shop practice of the individual plants. 17 Table VII gives the range of roughness for the typical operations tabulated. In any given.shop the range will probably be much smaller than that listed. TABLE‘VII RANGE OF ROUGHNESS OF INDUSTRIAL FINISHES Industrial Finishes Micro-inches rms. Rough turn 63 - 2,000 Rough mill 63 - 1,000 Shape 32 - 500 Rough grind 32 - 250 Finish mill l6 - 250 Smooth turn 8 - 250 Broach 8 - 125 Commercial grind 8 - 63 Finish grind 4 - 32 Internal hone l — 16 Polish 0.5 - 32 Superefinish 0.5 - 16 Lap 0.2 - 16 Sand castings 250 - 1,00 Forgings 63 ~ 250 Rolled surfaces 16 - 250 Die castings 32 - 125 Extrusions 16 ~ 250 The Handbook of Standard Time Data gives descriptions of machine finishes, how obtained, and when used. The following finishes have been acepted by a majority of the metal-working trades. Before proper feed and speed selection can be made, the required standard finish must be determined. The finish on the part to be machined can be specified on the drawings. 2American Society of Tool Engineers, Tool Engineers Handbook (New York: McGraw-Hill Book Co., Inc., 19:17, P. 2. 18 This listing shows what operations can produce each finish and under what conditions each finish is acceptable. Finishes are expressed in tenms of root mean square value (RiM.S.). #500 RwM.S.,Fini§h Produced by turning, facing, boring, milling, shaping, planing, sawing, and grinding. Acceptable when: a) The surface is to be refinished by machining other than grinding at a subsequent operation. b) The surface will have no contact with any other surface when the part is finally assembled. #250 R;M.SLgFin1§Q Produced by turning, facing, boring, milling, shaping, planing, sawing, and grinding. Acceptable when: a) The surface is to be refinished by grinding. b) The surface is to be bolted against a gasket. c) The surface is to be used for locating or measuring during a subsequent operation. ‘#l25_RgM.S. Finish Produced by turning, facing, boring, milling, shaping, planing, sawing, grinding, drilling, spot- facing, and counterboring. Acceptable when: a) The surface is clamped or bolted to another part at assembly, but need not form a complete seal, and is not slidably mounted. b) The surface is to be pressed onto or into ar- other part as a permanent assembly. #63 RJ’ILSL Finish Produced by turning, facing, boring, milling, shaping, planing, reaming, and abrasive cutoff. Acceptable when: 19 a) The surface is to be slidably mounted in contact with another surface. b) The surface is to be hand—finished by polishing for a low~speed bearing surface. c) The surface is to be hand-finished by scraping to form.a metal-toemetal seal, or for a low- speed bearing surface. #23_R.M.S. Finish Produced by turning, boring, milling, grinding, reaming, broaching, burnishing, rough emery buffing, and fine grit belt sanding. Acceptable when: a) The surface is to be used for a high-speed sliding or bearing surface. b) The surface is to be scraped or polished with a minimum amount of effort to obtain finer surface.specifications. c) The surface is of a quality comparable to a surface.normally ground. A #32 R,M.S. finish obtained by milling or turning will require a slight amount of polishing with emery cloth, performed as part of a machining operation. #16 R.M.§. Finish Produced by grinding, lapping, honing, broaching, scraping, boring, burnishing, and smooth emery buffing. Acceptable when: a) The surface is to be used for high-speed shaft bearings. b) The surface is to be used for heavily loaded bearings. #8AB.M.S. Finish Produced by grinding, lapping, honing, planishing, and fine emery buffing. Acceptable when: a) The surface is to be used for the interior sur- face of hydraulic cylinders. b) The surface is to be used for the bore of stainless steel. 2O #4 R.M.S . Finish Produced by grinding, lapping, honing, very fine buffing, and brite polishing. Acceptable when: a) The surface is to he used for cutting punches. #2 R.M}S, Finish Produced by grinding, lapping, and honing. Acceptable when: a) The surface is to be used for cutting dies.3 Figure 1 will clearly show the surface finishes available by different machining methods. 6. Work Piece fielding The size and weight of the work piece may determine whether horizontal or vertical loading will be most conveni- ent and profitable. This is ordinarily not of prime impor- tance for small diameter work, but when a work piece reaches proportions where crane loading becomes necessary, then a close analysis of the Job requirements is in order. The shape of the work piece determines the design and necessity for holding devices which in turn can influ- ence the choice of machining equipment. Completely unsym- metrical work may call for the use of a fourajaw independent chuck or other leWbacting holding device, which eliminates advantageous use of automatic or semi-automatic equipment. 3Victor K. Genger and Arthur A. Hadden, fiandhook ‘2; Standard Time Data (New york: The Ronald Press‘oafi 1954), pp. 26e28. 21 .H enemas ”H” \VV \VM.>\\L\ WW‘S WxaxSQ N‘\\W§K xxk Q§§xfi d\>\ \\W\>\\.\ _ Q3§WV §V§QN Qflqu NWQQ WE‘VK Nn‘\\\h. \\ Twz WM 3.x VVxhx xx “\v 9W \(N‘Vk \\V\VQQ \. N. no kc. \ w e .o S cw on o...» 8w SNocooPo 82 33 WEN WN§V\<\QNV\§\ WW~£m<>§K NU‘KQQMIKDLWWEQ 22 If the holding device is a fixture, its design will have considerable effect on the selection of a machine tool. A.simple fixture may be loaded quickly enough to be in con- formity with an automatic cycle, whereas a complete fixture is likely to raise the cycle time beyond the point of profit in an automatic machine tool. Hork piece holding methods will be grouped as follows: a Hand ~ Between centers In a chuck In a collet Mounted on a face plate Mounted on a carriage In a fixture on a face plate In a fixture on a carriage It'll 7. Thepfiumber of Pieces to be Made The importance of this factor in machine selection cannot be overemphasized. There are several methods used for determining which types of machines may produce certain Jobs most economically. Among the many factors directly involving lot sizes and frequency is their relation to the machine hours available. This introduces the matter of machine loading, which qualifies to some extent the possibility of assigning Jobs to certain types of machines already in the shop. Total production always involves a comparison of setu-up time and producing time for different types of turning machines. It simply is not profitable to produce a short rwn Job on a multiple spin.le automatic when an 23 extremely long set-up time is involved. Conversely, a long run Job on a hand turret lathe wastes the economics of auto- matic cycling, provided all other factors as previously outlined are favorable. The determination of the actual minimum.lot size of a particular machine part which can be run with profit on the single spindle makes an interesting example of some useful arithmetic. As an example, let us take an aluminum gear blank, suitable for production on a single spindle chucking auto- matic lathe. Operation records on the turret lathe show 636 pieces can be produced in 62 hours. (Hours cited , are total elapsed time, working time is equivalent to 51 minutes per hour.) This gives a production rate of 10.2 pieces per hour. To reflect overhead and machine charges, a rule of thumb based on the expectation of recovery of the full machine cost in 10 years can be used. Based on 2,000 hours of operation per year for a total of 20,000 hours, this means that each turret lathe hour is worth.$.50. Hence, to get the turret lathe per piece cost, hourly operator and machine expense is divided by pieces per hour, i.e.z $1‘65l$#:‘BO e $.21C3 Per Turret Lathe Piece Turret lathe set-up time was recorded at 1-1/2 hours at the same hourly rate, so turret lathe set-up cost for this particular operation including machine charges is 1-1/2 x $2.15 e $3.23. So far, half of the equation is obtained: $.2108 x L + $3.23 n The automatic production reacrd on this same part was 1.990 pieces in 91.66 hours, or: 11290 a: 21.7 pieces per hour 24 For a 10-year recovery the machine cost is again divided by 20,000 hours, which gives $1.00 per auto- matic hour. Setoup was figures as 2-1/2 hours at the same rate of $1.65. Thus: $1.62117$1.oo a $.l22l per automatic price and: 2-1/2 x ($1.65 + $1.00) a $6.63 set-up cost. These figures give the final equation: $.2108L + $3.23 a $.1221L + $6.63 To simplify ~ .1221L - 3.23 = «.122lL - 3.23 subtract .O887L + O a O + 3.40 To simplify } .0887 1 ,Jé .0887 divide L m 38.3 L a 38.3, Number of Pieces in Break-Even Lot. The use of some such procedure to figure "break even.point".relationships between hand and automatic equipment is vitally important to shops desiring to operate at lowest costs. For example, the arithmetic Just reviewed has de- fined the size of the Job lot where the automatic becomes competitive, for this particular Job, to the hand machine. Therefore, the productive capacity of the automatic may thus safely be applied to lot sizes in that range and the per piece savings realized for all gieces in excess of 38.3 contained in the Job run. Graph 1. will show the graphical presentation of the break even.method. u" it" From the previous exarple ani Graph 1. it can seen that the break even method compared cne machine tool “E. L. Murray, "Break Even Point," Screw Machine Engineering, August, 1952, pp. 47-48. Graph No.‘l.' Break Even Method ‘ 26 to another. The calculations and graphs always shows the comparison.for a certain work piece at the required con- ditions only and cannot be assured as a typical example. For a different work piece, different material and differ ent requirements the relationship may change entirely. For this reason the results of the calculations cannot be coded and placed on punched cards. When the” selection by other characteristics is finished, some cal- culations are required each time to compare the machine tools which are selected as suitable to perform the required operation. 8,U_Selection of Cuttinngools Selection of cutting tools or sometimes called, "small tools" is an important factor in machining operations, and covers such tools as drills, taps, die s, threading tools, reamers, counterbores, countersinks, milling cutters, hobs, breaches, etc. Standards have be destablished for certain tools such as taps, reamers, twist drills, and milling cutters. The standardization app ies to more important dimensions so that cutting tools made :y different mar1ufac turr smay be used interchangeably. There is no standard established for material used in different cutt ng tools. The compositirns of steels used 27 for tools are many and vary from one manufacturer to an- other, and the tools are continually being improved. No simple rule can be laid down for selecting a material that will meet the problems of a particular Job. A thorough analysis of the Job is the only basis for an intelligent solution to the problem. In the selection of workable steels, engineers should not hesitate to draw upon the experience of steel manufacturers. As an enample, the following are different steels used for tools, as based on.the practice of the Westing- house Electric and Manufacturing Company:5 1. Carbon Steel for Tool Shanks 2. Tungsten HighaSpeed Steel 3. Carbon Tool Steel 4. Carbon Die Steel 5. Carbon Steel Drill Rod 6. Oil-Hardening, Non—Deforning 7. Low~Tungsten, Chrome-Vanadium 8. Chrome-Vanadium.Steei 9. Alloy Die-Block Steel 10. Carbon.DieeBlock Steel ll. ChromeAVanadium Steel 12. LoweTungsten Alloy 5F. D. Jones and Erik Oterg, Machinery's Handbook (New York: The Industrial Press, :3;5), pp. 1506-1537. 28 13. Tungsten Fast-Finishing Steel 14. Tungsten-Chromium.Hot*Work Steel 15. HighnCarbon, High-Chromium 16. Cobalt High-Speed Steel 17. Chrome-Vanadium 18. Silicon-Molybdenum Steel Each of these tool materials has different properties, which also are important factors in selection of machine speed, feed, and horsepower. As an example, Table VIII will show the properties of several tool materials at room temperature. Studies and experiments have been made in the field of cutting tools and tool materials. From this previous data there are several established cutting tool groups from which to choose. Some manufacturing companies have selected some of the cutting tool groups and keep them in store as a stock item. In such a case the selection is simplier but not always the best. To go further with this approach it is assumed that the cutting tool is selected. The next step would be the determination of cutting speed. The cutting speed is governed principally by the hardness of the metal to be turned; the kind of steel or which the turning tools are made; the shape of the tools and their heat-treatment; the feed and depth of cut; the :3: .u :35.“ e...ro.-00I.'-Iv09. :eieeee .27; w — w... .32. .::._< . . \\‘ ‘\ ‘\ I ‘\ I \\ II I ll- Q-h\\ “‘0 3‘ uMI‘Ju\\a\ o-I“‘\-V\I\)Iw \IUII‘II- II.“ \ Q \ 0‘ ‘.‘.\. .1 \‘n‘.\\l\.| \ § \ ’. \ “‘x \k' -l” ”MN-mm nH-MHm-H-UM O s \O 0‘.- \ .. . ‘l .“ . .. 3 we \- um K- In- HHS..\I\DU Muz‘\fm-....\\ In.” .. ‘u‘ .‘ .‘ -’.AII|‘ hp ..vaw.sou nNiumAu 0\ \ O\ O‘\ O .‘I I ‘ \n‘ l \x x e 5 \\ \s \\ NI N N“ ”v (I h d‘l\{“d\ Iva \N elf-mm}. |.“-1I\IkH * -\.!‘I‘J\|‘\.\.) nvnv “wax «.x urn.» mu '1‘ ‘. \ \\. ..\ \.* \11 {1‘ .“Q. \‘ne ‘\ h L 9-H m- \f N 'U‘ ea..w>x-emmrm \. \x \.ea. 1 -4 4 \X“ I“ no .u «\n‘ O»..- M'Lr N tmg N‘..~ \! - \l \ o \\ . u \I A.\- \ s \- OC e s 3; C . a FCC 00 000 been 000 URN .u—\_.L kid-uh -w....-...C - CC — LL :0 Tia CCECU 000.com ooe rpwdrhwm o>dmwekofioo n.3wvhmm Haenflpm . \CO g «TAM 300.com CA“. \ n 030 .L 3.521.; ~A3wd< fi.n.@ 9...... seeo x-eo-oo uni. Assam .Uamcdm HI.qu .. t . A! .. _ .' _ . u‘ ' , . , . . cm I, w I II. I? ii... I. _ I’I’I ’ P .0... 'I’Il '1" . _ . (A. ’5]! “a; if o I ’I’Il’ . ’Jllllfll') 4 5 ‘50s . II . r m a I . If e ...I a L.. ’I” / H g [If], \ o, I i II, M 7/ °\~\.“ . / Inf / e. i _ ~00 : M WI I III. I I one . a / _ I / . ... 3 .i3sosilsliai! . / 33.38.591.128. 83.33518 \1 . I! ....l / Ices gggfiétg‘gl‘ giefi’icifltli 3.9.9.53 1.3.3. lotions-813361.41» 5.08.8333 oéioioflalfllsllél 2.0.81 ... .0... ll 31;. ...-1%.iiefoflli \\ EjizsgiljJ—i‘ T i‘gi. Ji'guénop in,“ . .13. 3133‘s“!!! 9'5! {If what-! no. pun. ‘Husn 03-hb3u OI n q nan n x ' In- uqmpau no poo, "mo poo an: )0 wisp floor In 'W, “0' ”01“" 1001) OJAOWI; SiHDNt DIIOD S\E< .\ ~ in § % ..n g , ‘mmommu-omnoono-cmawooku-mm W ' , ... a S singiniméz 42 run-mun W“ I I 'x b ! I,8 ! t I I t I I l I I a I I am» or to: - mm WWW” vr'm'mrrv] rvvv I'm-flan" mmnmm F'. i s i t i : g/i a z s a I 2 ‘ J A," nooucv or ocpm l Hams; ,4" IT ' . : I’ ‘ 0 mm con-- ,/ , mum. «on u “ l ft“ m E I 3 I ' I u ‘l . C’fl’flOOUCY "All ' \\ l U’FICIENC‘ 4 HRCCNT s 0 g I u ’ ' a : \ /’ ,0 sumowcr or amcnmcv & mnssrowcn 1 I.” I- /" 1” . /’uovon ascrowcn ’ . rr-H'FPHTTTH'! "WIT [11 1mm mm]! mlmqrmlwrmf r1111 "7'" n] a o I I r‘ 3 i C . 8 3 Gilbert and Trucken-Miller Nomograph* -_Graph No. 2 *American Society of Tool Engineers, Tool Engineers Handbook (New YOrk: McGraw-Hill Book 00., Inc., 1951), P» . 43 the chosen cutting speed of 60.5 fpm is combined with the chosen.feed of 0.0625 in. to give a point on line B; this point is combined with the known machine efficiency of 60 per cent 50 find that the required motor horsepower is 3.75. The Warner and Swasey Company represents another nomograph for determining the relation between diameter, REM cutting speed-feed-depth of cut-cubic inches per minute and horsepower required for various materials. This nomograph can be used for turning operations. Tool life and power consumption are both functions of the principal machine and work material variables. In any given machining operation any given material is desir- able to adjust the machine variables to such values that the motor is loaded to rated capacity and at the same time a suitable tool life is obtained. Under these conditions, [maximum.output will be obtained from the given machine tool. This principle is basic to the economical machining of metals. A rough estimate of the proper combination of machine variables to accomplish this result can be made from the various data, equations, and nomographs. Finally, check surface and tollerance specifications and their influence on metal-removal rate. From previous discussions it can be seen that the selection of small tools is one of the most difficult 91b1d., p.349. 44 “DIES bfl .....13 n P .IIbI-DPPb—DDDb-PLPII .- ”i r-l.‘ w. mwmlq‘sllu t... In is L mgfi4+M4rL1+sa:M...zam.z:2a.n.....;.l-1....u . w a. m a “raw” ...- u % e.1.e4m . B u “u ”up“ Ftp-PP. p LhL-anP-...»hbbpphpp-nn-nnnn- P .Pib ” upbt-bb- b phrbhhb ! P _ snub-unhth up .hthb PLh b . ......Ipnh-b-b Db n “mm m www.mm.wm :m min an.“ n a s n.» O 7 . Q 3 .4 I d I o .D-DbDeb-D.h-DIDtDII-DI-hhbbrp—bpbeIbbthDbh-bnbb-IDPb—nbbb burn—Ibbb-hbbubbbi mm» a. a: a “mu :3 E.___.________ .w 1. .2. :2: m3: h P n E -.---s-pbun..[ .. . P n p nppp 1“-111‘*““ - “ ‘ ‘ ”I 1 “-1II +‘ ‘ - ‘ 1“ I-JI" ‘ judfi ‘ - 1 u a a , e... . a mu.» ‘q WI! Chart* ~ kl .- Metal Cutttn Graph No. 4. .L‘ the Mos meanv. *How to afid““ get Swasev Co problems in machine tool selections. As there is no set standards for cutting tools the variations are many. 'Variables like cutting tool material and microstructure, work piece, material and hardness may change the cutting speed, feed and horsepower over a very wide range. Small tool selection will be considered as a dif- ferent part of machine tool selection and only the results will be introduced in this approach. There will be no coding for'small tools but there will be coding about cutting speed, feed and horsepower available for each machine tool. 9. Relative Cost Balanced relationship exists between a slower basic producing unit, which could be equipped with special tools to accelerate itssproduction rate, and an inherently faster producing unit. The tooling possibilities shOuld first be checked for a basically slower producing unit, because this type unit is.normally less expensive than a basically faster unit, before concluding that the faster unit is desirable on the Job. The cost to produce is hard to determine, because there are very many variables involved. Table XI will show the relative cost to produce, and is the means by which this 46 factor will be evaluated in the proposed approach, to the selection of a.machine tool. TABLE XI. RELATIVE COST TO PRODUCE Suitable for Relative Cost Tolerances‘i Method of Producing Finish to Produce 0.0005 Ground, micro-honed, lapped, burnished 40 0.0005 Ground, honed, lapped, burnished 35 0.001 Ground, rolled, filed, lapped 25 0.002 Square nose tool with drag feeds to suit, ground, rolled, filed, milled 18 0.003 .Shaped, milled, ground, reamed, rolled, broached 13 0.004 Shaped, ground, broached, milled 9 0.007 'Shaped, rough ground, milled, turned, bored, drilled, spat faced 6 0.013 Shaped, rough ground, milled, turned, bored l3 0.025 Round nose tool 3/6#" to l/“" feed 2 0.050 Round nose tool 3/32" to 3/8" feed 1 47 Rhea more precise cost is required, data from pre- vious experience can be used. The time standards from the time study department can help to determine Operations and set up time. If such data is not available for the engineers selecting production equimxent, handbooks of standard time data can be used. Standard time data, properly applied, can determine exact cost before the work goes into the shop. 10. Personnel Factors Among all of the personnel factors which enter into the selection or a machining ,equipmnt, skill is the most important in same shops. The skill available will determine to some extent whether Jobs may be placed on hand operated machines or on some other type. Frequently, due'toa lack of available skill, some Jobs which might well be machined on automatic spindle autmtics, would call for the simplification of operations across two or three other types of machines in order to balance the skill available to the total machining cf the work. This factor 1: not a characteristic of the machine tool, but it is related to the machine tool and typical plant situations. Therefore, it cannot be placed on a punch card but has to be evaluated .inrevery case when selecting new machine tools. 48 lléfrloor Space At this point on selection of equipment, some infor— mation should not be over looked. Not only the floor space where machines are to be placed is important, but also general characteristics of the plant and layout. For heavy equipment sometimes important is the height of ceiling and aisle width. Outside turning radius should not be overesttnated when machines are to be turned around the corners in order to be placed in the desired place. Floor space is a very variable factor. In.many cases when operation flow changes it also changes plant layout. 50 this factor*cannot be evaluated, when selecting machine tools, as machine tool characteristic, but only in relation to plant layout. 12:: Newt Always check the allowable floor load before selecting any equipment. It is very important as a factor in multiple story buildings, where overestimates can bring serious accidents and property damage. _ Likewise as floor space this factor is related to plant layout and should be considered in.machine tool selection. CHAPTER IV GROUPING AND CODING THE FACTORS In previous chapters the importance of all deter- mining factors in machine tool selection were discussed. The next step in this proJect will be grouping and coding the factors in such a manner that they can be placed on punched cards. Two general types of punched cards are in common use, namely, hand sorted and machine sorted. There are various systems of hand sorted cards. Most commonly known is McBee Keysort System. This system.uses marginally punched cards for accurate sorting into any required order. The Keysort cards are specially designed to fit the requirements of each specific Job. It may be as small as 2" x 3-1/2" and as large as 8".x lO-l/2". Sample cards are shown in Figure 2. The holes around the sides of the Keysort card are coded by'notching taway that portion.of the card between the hole and the edge. These notches allow the coded cards to be separated fro '\ ’3 A i unnotched cards when a sorting needle is inserted in one of the holes of a group of cards. Since notched cards have nothing to support them on the needle, they fall from the group, while unnotched cards remain on the needle. Keysort Cards ... Figure 2. l . 50 51 Most commonly used machine sorted card system.is the International Business‘nachine [hereinafter referred to as IBM], which uses a small card 7-I/2” by 3-1/2" on which in ten.rows and eighty columns small holes are punched. The holes are machine punched and also the cards are machine sorted. In this project the IBM card will be used. [See Figure 3.] A.direct code will be used. A direct code, by def- inition uses a single hole to represent a single idea. In this system, if we have N ideas to code, we will require N holes in each card. Or, to state the matter in a different way, if.our card has N holes; direct coding will force us to analyze the subject matter in terms of not more than N concepts. 1. The first group.covers the classification chart of machine tools. .Classification chart shown in Appendix A will be used. This chart will be used when a group of machine tools have to be selected and sorted from the whole catalog, and sometimes, when the selected machines are not available and closely related ones.must be chosen. This machine code will be punched in the first four columns. For example, planer, rotary 18-70 holes are punched~~ column 1 row column 2_row column 3 row column 4 row oqmw 2. The next group covers the characteristics of the surface to be machined and the holes are punched as shown: 52 choc EMH .m mhswfim 'rflflflfllnflSgfllfiunsaufl'n'an'anflllv' a . I . a ,! ..‘1. II I’..‘ ‘ I like: 1.3!“..vlfi Jig“... I... . \n.l. 1.! . u .l 3"‘HUQ'Hfin‘nlfifififlflfifiufl‘tflfifleSttfifibg=2ccuomen” , . 7* .=.w.m_ .:.a.m :ihflflfim szHmzmzwn #444 ,.H,.ian.xuaeea W. i‘lfiubhtlll Fin I: 53 Column 59! A -- Flat 5 l .B -- External Cylindrical 6 2 C -- Internal Cylindrical 3 JD —~ External Taper , 4 E -e Internal Taper 9 5 F ~~ Contour 10 6 G -~ Key Hays 11 g H -- Slots 12 I uh Threads 1 9 J ~~ Knurling 1 l K -- Gear 15 2 L -- Multiple 16 3 3. This group covers maximum.allowable work piece dimensions for certain machine tools. Dimensions will be grouped in four groups. 1. Length 2. Width or DJ). 3. Height or I.De 4. Hole depth fMaximum.dimensions will be punched on a card without coding. Holes for length dimensions will be punched in columns 17, 18, 19. Example as follows: Column. _Row 5" length 19 5 128" length 1g 1 1 2 19 8 In the same manner dimensions will be punched for width or 0. D. using columns 20, 21, 22; for height or I.D. columns 23, 24, 25; and for hole depth columns 26, 27, 28. For spherical diameter use diameter dimensions once for each of the following-~length, width, and height. For 7" spherical diameter holes are punched in row 7 in the following columns-~19, 22, 25. 54 4. Tolerances are grouped in ten groups and there is one hole for each group. Eslusn. 52s 0 + .0000 + .0000 incl. - .0000 — .0010 29 0 l + .0000 + .0000 incl. 5 00010 - .0015 30 l 2 + .0000 + .0000 incl. b .0015 - .0020 31 2 3 + .0000 + .0000 incl. . .0020 - .0030 32 3 4 + 0000 + .0000 incl. - 10030 - .0050 3 u 6 '3 .0010 'i .0020 incl. 35 6 g ‘i .0020 '1 .0040 incl. 36 g i .0040 :3; .0060 incl. 3 9 1 .0060 in 0100 incl. 3 9 5. Surface finish microinches (rms) is coded as follows: Column :52! o o P“ .5 111019 9 o l .5 9" 1 11161. O l 2 1 -~ 5 incl. 41 2 3 5"." 10 11101. 1+2 3 5 20 "" 50 11101. p 5 6 50 -— 100 incl. 45 6 g 100 -- 200 incl. 46 g 200 «a 500 incl. fig 9 500 over 9 6. The.next group covers work piece holding methods, and holes are punched in column49. s2: 1. Hand 1 2. Between centers 2 3. In chuck or collet 3 4. on face plate 4 5. 0n carriage 5 6. Clamp or fixture 6 The work piece material is determined by product engineers and is always given on a drawing or a blue print. 54 4. Tolerances are grouped in ten groups and there is one hole for each group. EQEEEB .52! 0 + .0000 + .0000 incl. - .0000 - 00010 29 0 l + .0000 + .0000 incl. . .0010 - .0015 30 l 2 + .0000 + .0000 incl. . .0015 - .0020 31 2 3 + .0000 + .0000 incl. - .0020 - .0030 32 3 4 + .0000 + .0000 incl. - .0030 - .0050 3 4 5 ‘3 .0005 ‘1 .0010 incl. 3 5 6 .1 .0010 ‘3..0020 incl. 35 6 g 1 .0020 i .0040 incl. 36 g 3:. .0040 i .0060 incl. 3 9 ‘1 .0060 ‘1. 0100 incl. 3 9 5. Surface finish microinches (rms) is coded as follows: Column. 52! 0 0 "' .5 1.1101. 9 O l .5 e- 1 incl. 0 l 2 1 ~"' 5 11161. “‘1 2 3 5..-. 10 11101. 42 3 4 10 -- 20 incl. :2 4 5 20 -- 50 inol. 5 6 50 -- 100 incl. 45 6 7 100 -- 200 bncl. 46 g 8 200 -1 500 incl. fig 9 500 over 9 6. The next group covers work piece holding methods, and holes are punched in column.49. 5.9.: 1. Hand 1 2. Between centers 2 3. In chuck or collet 3 4. on face plate 4 5. 0n carriage 5 6. Clamp or fixture 6 The work piece material is determined by product engineers and is always given on a drawing or a blue print. 55 The next step is the selection of cutting tools. From.manufacturers' catalogs or machinery hand books the selection can be made quite simply. Cutting tools and work piece material determine the relationship between cutting speed, feed, depth of cut, and horsepower required. All of these values can be found from charts or nomographs. The ranges of those values are divided in.groups and coded and for each of the code numbers there is a hole assigned. These factors are grouped as follows: 7. (a) Cutting speed for flat surfaces-~8EM Column. Row 0 0 10 BEN incl. ”17' 2 10 20 incl. 51 2 i 20 50 incl. 52 2 50 100 incl. 5 5 100 500 incl. 5 5 6 500 1000 incl. 55 6 g 1000 3000 incl. 56 g 3000 over 57 (b) Cutting speed for turning, drilling, and boring operations-ARIN Column Row 1 0 10 incl. . 53 '7I" 2 10 20 incl. 59 2 2 20 50 incl. 60 a 50 100 incl. 61 5 100 500 incl. 62 5 6 500 1000 incl. 6 6 g 1000 3000 incl. 6 g 3000 over 65 8. The horsepower required is directly punched on the card without using code. Columns 66 and 67 are used. For example: For 15 horsepower holes are punched-- column 66 row 1 column 67 row 5 56 The commonly used horsepower motors in machine tool indus~ try are 3 or less, 5, 7-1/2, 10, 15, 20, 25, 3o, 40, 50, and sometimes over. If the horsepower is not given in a manu- facturers' catalog, as for example, on some buffing and polishing machines, mark and punch'"0" on the card in the row "0" in both columns. 9. Threads per inch are coded as follows: Column ‘Egg 1 1/2 2 incl. 68 1 2 2 10 incl. 69 2 R 10 25 incl. 70 2 25 50 incl. 71 5 50 100 incl. 72 5 6 100 over 73 6 10. For tapping operations only one punched hole is used-u'"0," column.7h, row 0, thus determining if the machine is able to perform tapping Operations. 11. The last group shows feed rate in./rev. or in./ stroke and is coded as follows. 0 Hand feed 75 0 l .0001" .001" incl. 75 l 2 .001" .01" incl. 76 2 3 .01 .10 .incl. 7 3 u .10 .25. incl. 7 4 5 .25 .50 incl. 79 5 6 .50 over 80 6 A very important factor is the number of pieces to be produced. This factor cannot be worked into general punched card patterns, because the relationship between two groups of machines are good only for the one particular kind of work piece. For a different kind of product the 57 relationship can change completely. At this point further selection.by punched cards is stopped. The remaining characteristics must be analyzed and engineering decisions are required. The importance of those.factors was discussed in previous chapters. Personnel factors, floor space and weight have to be checked at the plant and it can vary from time to time, therefore those factors also are not placed on punched cards. Besides the punched information the card can contain other information such as, weight, price, over-all dimension, etc. Also sources of information.or catalog numbers may be helpful. - CHAPTER'V PREPARATION OF PUNCHED CARDS The next step is the preparation of punched cards. For each machine tool one card will be used. Punched cards are prepared from.data furnished by the manufacturer. This task is simplified by using inventory form to tabulate all the information. [See Table XII.] For each card one line is used. In column lines the numbers written correspond to the row'numbers in which the hole is punched. For example, in line 3 row 18 number 6 is written, that means, hole will be punched in the third card in.row 18, line 6. when the information in such a manner is collected, the inventory ferm is used to prepare the punched cards. All the information must be written on a card in the provided places. All characteristics discussed and coded in the previous chapter must be compared with the machine data and corresponding code numbers marked. From.the written code corresponding holes in the cards are punched. If the machine tool classifies in more than one group, all the group codes shall be marked and corresponding holes punched. For the groups length, width, height, hole depth, horsepower, codes are not given. The maximum dimension will 59 Each zoo—hours” I “““""""a:333:53==!3=flfll833lliiflfildiflflilIRRIlI' 8:398: at... n.+sr.uu. uni-......l...44.3.4.2...crass-.....uamiasaT-fi.J...._ lazaanlocpoo o \n»\V5N~1 NbNH‘fiN .o ‘ Nb 0 Q o saukvnplu s~¥~¥nw o a 3. e o o RKNH§MN\N \KNV‘MN 0 us we a o o e -uk§-~w \ans‘nw u \ xx 9 Q o u snhh\nw\ \ausrnd. o u e» e 9 c K s~n~nnw~ SsNHVMN o u \x Q Q whens onevew 6‘ 535‘s «usuhon so Na \V a have shrew onkenw o\ ever» usxaskoe he «s an a have xktnw oNH‘eN ox “whrn «ssaukbn no N\ \w w hove NHVnN oPH‘MN ex KNHV Nuksflh§fi «Q N\ up 5 New» uhvn~ enhvnw oxsmnuw «ssnwkrn so .- \N a moon thn~ crannw ex ante «sssnken a» N\ ~\ ~ ween .32.. 5343 a fig 33 Nose new.» .3 s up a use .33 3.23 e 13.? 3:31. 3 a 3 s was» been 0343 w 3on . m: as...» no a L.\ 5 Neon MM‘MN~LNW$nN\ §s§h§n~xiquV9is o‘euh‘nwxsssuuktqq\o qkhhhpkkhhhh W f!3. 77 .- ‘.0901 72 . ' .0017 91 .0912 90 .9919 1191100 M1110 .120 g .091 09 .m 09 .0091 00 .9092 . 07 .9090 99 .0091 07 .0090 09 .0929 .200 . 07 .0099 ,. 99 .0991 . 00 .0027 91 .9929 Kn1171 T0010} {On 00 ' .0070 N ’ .1070 70 .OM 00 .0000 . 107111101 011 90 _ .0100 09 -0110 79 .9120 90 .0129 1(111171—01000 9119. 2. -90 .0079 90 .9970 70 .9999 99 . 9090 01mm 0- 70.1... 109 .909- 07 .9029— 90 .0929- 79 .9924- .9912 .0099 9~ .9090 .9994 1100111070 11111107 1A" ,’ " 70 .9099 70 .0134 02 .1030 07 .0020 V2"071m7 .- .0901 .0917. 92 .9012 97 .9949 111.191; .092 09 .9010 00 .0900 70 .0990 99 .9999 091011 .129 99 .0912 1 90 .0012 74 .0011 99 .9911 .197 99 ' .9012 97 .0912 77 .0011 71 .9911 .299 99 .0919 92 .9911 91 .9912 79 .9912 171001111110 31001 0010 91.2.. .01.. ...-.-. \ F. K '1 BIBLIOGRAPHY BIBLIOGRAPHY Books American Society of Tool Engineers. Tool Engineers Hand- Book. New Ybrkx McGraw~Hill 353E CO.,‘Inc., 1951. Departments of the Army, the Navy and the Air Force. Director of Metalwork Machiner . Department 0 enseT— Washington, b, C Government Printing Office, 1956. Genger, Victor x. and Arthur A. Hadden. Handbook of Standard Time Data. New Ibrk: The Ronald PFess Company. I950. Jones, F. D. and Erik Oberg. ‘Machiner 's Handbook. New York: The Industrial Press, I953. Periodicals Fraser, George T. "Tool Selection Cuts Machining Costs," American Machinist, January 9, 1950, p. 122. Frommelt, H. A. '"How to Set—Up Carbide Milling Job," American Machinist, April 24, 1957, pp, 77-82. LeGrand, Ruper. '"Airforce--Curtis Wright--Ford Report-- Machinability Depends on Microstructure," American Machinist, November 27, 1950, p. 109. "Machining Standard Steels," Republic Steel Corporation, The Iron 5&3, July 25, 1957, pp. 123-127. '"Properties of Several Tool Materials at Room Temperature," American Machinist, October 15, 1951. "U. 3. Air Force Machinability Report, 1951," American Machinist, October 1, 1951, pp. 161-168. Miscellaneous General Motors Engineering Standards, Detroit, Michigan. HOW’EQ Get the Most Out 9: YOur Turret Lathe, The Warner and Swasey Company, Cleveland, Ohio. Machine Tool Catalogs, Sweet’s Catalog Service. Date Due 3.3::3 13.3: 13“ Demco-293 N ”7171111 11711111131111 N T AR 131111171417 1'1 11111111? 11'“ 6