MANUFACTURING PROCESSES CHAPTER NINE
OBJECTIVES 1. Describe the role of computer-aided design in project development. 2. Define rapid prototyping and list four rapid prototyping technologies. 3. Describe the role of design in manufacture, assembly, disassembly, and service. 4. Define modeling for assembly. 5. Describe the role of material selection and material properties. 6. List the major manufacturing processes. 7. Look up accuracy and surface finishes for manufacturing processes. 8. Describe the role of measuring devices in production. 9. List factors that determine the cost of manufactured goods. 10. Define computer-integrated manufacturing. Technical Drawing with Engineering Graphics, 14/e Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman © 2012, 2009, 2003, Pearson Higher Education, Upper Saddle River, NJ 07458. • All Rights Reserved.
UNDERSTANDING MANUFACTURING Manufacturing is generally a complex activity involving a wide variety of resources and activities such as: • Product design • Purchasing • Marketing • Machinery and tooling • Manufacturing • Sales • Process planning • Production control • Shipping • Materials • Support services • Customer service Technical Drawing with Engineering Graphics, 14/e Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman © 2012, 2009, 2003, Pearson Higher Education, Upper Saddle River, NJ 07458. • All Rights Reserved.
THE DESIGN PROCESS AND CONCURRENT ENGINEERING Sharing product design data among multiple users concurrently can shorten the time to product realization and result in a better product. Design and manufacturing activities have traditionally taken place sequentially rather than concurrently or simultaneously. Technical Drawing with Engineering Graphics, 14/e Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman © 2012, 2009, 2003, Pearson Higher Education, Upper Saddle River, NJ 07458. • All Rights Reserved.
COMPUTER-AIDED DESIGN AND PRODUCT DEVELOPMENT Computer-aided design (CAD) allows the designer to conceptualize objects more easily without having to make costly illustrations, models, or prototypes. These systems are now capable of rapidly and completely analyzing designs, from a simple bracket to complex structures. Technical Drawing with Engineering Graphics, 14/e Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman (Ford Motor Company/Dorling Kindersley. ) © 2012, 2009, 2003, Pearson Higher Education, Upper Saddle River, NJ 07458. • All Rights Reserved.
COMPUTER-AIDED ENGINEERING ALLOWS FOR FUTURE MODIFICATION Computer-aided engineering (CAE) allows the performance of structures subjected to static or fluctuating loads and various temperatures to be simulated, analyzed, and tested efficiently, accurately, and more quickly than ever. The information developed can be stored, retrieved, displayed, printed, and transferred anywhere in the organization. Fiberglass Chassis for a Lotus Car Being Removed from the Mold. (Lotus Cars Ltd. /Dorling Kindersley. ) Technical Drawing with Engineering Graphics, 14/e Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman © 2012, 2009, 2003, Pearson Higher Education, Upper Saddle River, NJ 07458. • All Rights Reserved.
COMPUTER-AIDED ENGINEERING LINKS ALL PHASES OF MANUFACTURING Computer-aided manufacturing (CAM) involves all phases of manufacturing by utilizing and processing further the large amount of information on materials and processes collected and stored in the organization’s database. Computers now assist manufacturing engineers and others in organizing tasks such as programming numerical control of machines; programming robots for materials handling and assembly; designing tools, dies, and fixtures; and maintaining quality control. Car Frames Being Welded on a Robotic Assembly Line. (Courtesy of Adam Lubroth / Stone/Getty Images Inc. ) Technical Drawing with Engineering Graphics, 14/e Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman © 2012, 2009, 2003, Pearson Higher Education, Upper Saddle River, NJ 07458. • All Rights Reserved.
RAPID PROTOTYPING Rapid prototyping systems allow the engineer to develop a prototype directly from a CAD design within minutes or hours instead of the days or weeks it might otherwise take to create a prototype part. (Courtesy of Stratasys, Inc. ) SLA Rapid Prototyping System. (Courtesy of 3 D Systems Corporation. ) Technical Drawing with Engineering Graphics, 14/e Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman © 2012, 2009, 2003, Pearson Higher Education, Upper Saddle River, NJ 07458. • All Rights Reserved.
RAPID PROTOTYPING TRANSLATING THE MODEL Today’s major rapid prototyping systems all work on a similar principle: they slice the CAD model into thin layers, then create the model, layer by layer, from a material that can be fused to the next layer until the entire part is realized. To send a CAD file to most rapid prototyping systems, often you export a file in the STL ( stereolithography) file format. Technical Drawing with Engineering Graphics, 14/e Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman Faceted Surface on a CAD Model Exported for Protoyping (Lockhart, D. ; Johnson, Cindy M. , Engineering Design Communication: Conveying Design Through Graphics, 1 st, © 2000. Printed and electronically reproduced by permission of Pearson Education, Inc. , Upper Saddle River, New Jersey. ) © 2012, 2009, 2003, Pearson Higher Education, Upper Saddle River, NJ 07458. • All Rights Reserved.
TYPES OF RAPID PROTOTYPING SYSTEMS • Stereolithography Apparatus (SLA) • Solid Ground Curing (SGC) • Selective Laser Sintering (SLS) • Fused Deposition Modeling (FDM) • Laminated Object Manufacturing (LOM) • Topographic Shell Fabrication (TSF) • 3 D Printing • Rapid Tooling • Direct Shell Production Casting (DSPC) 3 D Printer Model. (Courtesy of Z Corporation. ) Technical Drawing with Engineering Graphics, 14/e Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman © 2012, 2009, 2003, Pearson Higher Education, Upper Saddle River, NJ 07458. • All Rights Reserved.
DESIGN FOR MANUFACTURE, ASSEMBLY, DISASSEMBLY, AND SERVICE This area is termed design for manufacture (DFM). DFM is a comprehensive approach to producing goods and integrating the design process with materials, manufacturing methods, process planning, assembly, testing, and quality assurance. (Courtesy of the New York Times. ) Technical Drawing with Engineering Graphics, 14/e Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman © 2012, 2009, 2003, Pearson Higher Education, Upper Saddle River, NJ 07458. • All Rights Reserved.
MATERIAL SELECTION The following are the general types of materials used in manufacturing today, either individually or in combination: • Ferrous metals: carbon, alloy, stainless, and tool and die steels. • Nonferrous metals: aluminum, magnesium, copper, nickel, titanium, superalloys, refractory metals, beryllium, zirconium, low-melting alloys, and precious metals. • Plastics: thermoplastics, thermosets, and elastomers. • Ceramics: glass ceramics, glasses, graphite, diamond, and diamond-like materials. • Composite materials: reinforced plastics, metalmatrix and ceramic-matrix composites. These are also known as engineered materials. • Nanomaterials: shape-memory alloys, amorphous alloys, superconductors, and various other materials with unique properties. Technical Drawing with Engineering Graphics, 14/e Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman Standard shapes are often used in materials testing to make it easier to compare results. (Courtesy of Clive Streeter © Dorling Kindersley. ) © 2012, 2009, 2003, Pearson Higher Education, Upper Saddle River, NJ 07458. • All Rights Reserved.
PROPERTIES OF MATERIALS Manufacturing properties of materials determine whether they can be cast, formed, machined, welded, and heat treated with relative ease General Manufacturing Characteristics of Various Alloys Methods used to process materials to the desired shapes can adversely affect the product’s final properties, service life, and cost. Technical Drawing with Engineering Graphics, 14/e Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman © 2012, 2009, 2003, Pearson Higher Education, Upper Saddle River, NJ 07458. • All Rights Reserved.
COST AND AVAILABILITY OF MATERIALS APPEARANCE, SERVICE LIFE, AND RECYCLING Cost and availability of raw and processed materials and manufactured components are major concerns in manufacturing. Competitively, the economic aspects of material selection are as important as the technological considerations of properties and characteristics of materials. The appearance of materials after they have been manufactured into products influences their appeal to the consumer. Time- and servicedependent phenomena such as wear, fatigue, creep, and dimensional stability are important. Technical Drawing with Engineering Graphics, 14/e Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman Recycling or proper disposal of materials at the end of their useful service lives has become increasingly important in an age when we are more conscious of preserving resources and maintaining a clean and healthy environment. © 2012, 2009, 2003, Pearson Higher Education, Upper Saddle River, NJ 07458. • All Rights Reserved.
PROCESSING METHODS The broad categories of processing methods for materials are: • Casting • Forming and Shaping • Machining • Joining • Finishing Selecting a particular manufacturing process, or a series of processes, depends not only on the shape to be produced but also on many other factors pertaining to material properties. Technical Drawing with Engineering Graphics, 14/e Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman © 2012, 2009, 2003, Pearson Higher Education, Upper Saddle River, NJ 07458. • All Rights Reserved.
DIMENSIONAL ACCURACY AND SURFACE FINISH Ultraprecision manufacturing techniques and machinery are now being developed and are coming into more common use. For machining mirrorlike surfaces, for example, the cutting tool is a very sharp diamond tip, and the equipment has very high stiffness and must be operated in a room where the temperature is controlled within 1°C. Highly sophisticated techniques such as molecular-beam epitaxy and scanningtunneling microscopy are being implemented to obtain accuracies on the order of the atomic lattice 0. 1 nm. Technical Drawing with Engineering Graphics, 14/e Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman © 2012, 2009, 2003, Pearson Higher Education, Upper Saddle River, NJ 07458. • All Rights Reserved.
MEASURING DEVICES USED IN MANUFACTURING Although the machinist uses various measuring devices depending on the kind of dimensions (fractional, decimal, or metric) shown on the drawing, to dimension correctly, the engineering designer must have a working knowledge of common measuring tools. Most measuring devices in manufacturing are adjustable so they can be used for a range of measurements, but some measuring devices are designed to be used for only one particular dimension. Technical Drawing with Engineering Graphics, 14/e Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman © 2012, 2009, 2003, Pearson Higher Education, Upper Saddle River, NJ 07458. • All Rights Reserved.
OPERATIONAL AND MANUFACTURING COSTS The design and cost of tooling, the lead time required to begin production, and the effect of workpiece material on tool and die life are major considerations. Depending on its size, shape, and expected life, the cost of tooling can be substantial. For example, a set of steel dies for stamping sheet metal fenders for automobiles may cost about $2 million. quantity of parts scrap rate safety Technical Drawing with Engineering Graphics, 14/e Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman Availability of machines and equipment © 2012, 2009, 2003, Pearson Higher Education, Upper Saddle River, NJ 07458. • All Rights Reserved.
COMPUTER-INTEGRATED MANUFACTURING Few developments in the history of manufacturing have had a more significant impact than computers. Computer numerical control (CNC) Adaptive control (AC) Industrial robots Automated handling of materials Automated and robotic assembly Computer-aided process planning (CAPP) Group technology (GT) Just-in-time (JIT) Cellular manufacturing Flexible manufacturing systems (FMS) Expert systems Artificial intelligence (AI) Technical Drawing with Engineering Graphics, 14/e Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman © 2012, 2009, 2003, Pearson Higher Education, Upper Saddle River, NJ 07458. • All Rights Reserved.
MANUFACTURING METHODS AND THE DRAWING In designing a part, consider what materials and manufacturing processes are to be used. These processes will determine the representation of the detailed features of the part, the choice of dimensions, and the machining or processing accuracy. The principal methods of metal forming are: • Casting • Machining from standard stock • Welding • Forming from sheet stock • Forging Forged Technical Drawing with Engineering Graphics, 14/e Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman Casted or Forged © 2012, 2009, 2003, Pearson Higher Education, Upper Saddle River, NJ 07458. • All Rights Reserved.
DIMENSIONING CHAPTER TEN
OBJECTIVES 1. Use conventional dimensioning techniques to describe size and shape accurately on an engineering drawing. 2. Create and read a drawing at a specified scale. 3. Correctly place dimension lines, extension lines, angles, and notes. 4. Dimension circles, arcs, and inclined surfaces. 5. Apply finish symbols and notes to a drawing. 6. Dimension contours. 7. Use standard practices for dimensioning prisms, cylinders, holes, and curves. 8. List practices for dimensioning a solid model as documentation. 9. Identify guidelines for the dos and don’ts of dimensioning. Technical Drawing with Engineering Graphics, 14/e Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman © 2012, 2009, 2003, Pearson Higher Education, Upper Saddle River, NJ 07458. • All Rights Reserved.
UNDERSTANDING DIMENSIONING The increasing need for precision manufacturing and interchangeability has shifted responsibility for size control to the design engineer or detail drafter. Practices for dimensioning architectural and structural drawings are similar in many ways to those for dimensioning manufactured parts, but some practices differ. Refer to the following standards: • ANSI/ASME Y 14. 5 -2009 Dimensioning and Tolerancing • ASME Y 14. 41 -2003 Digital Product definition Data Practices • ASME B 4. 2 -1978 (R 1999) Preferred Metric Limits and Fits Technical Drawing with Engineering Graphics, 14/e Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman Automatically Generated Dimensions. Views and dimensions can be generated automatically from a solid model. (Courtesy of Robert Kincaid. ) © 2012, 2009, 2003, Pearson Higher Education, Upper Saddle River, NJ 07458. • All Rights Reserved.
THREE ASPECTS OF GOOD DIMENSIONING Technique of dimensioning Placement of dimensions Choice of dimensions Technical Drawing with Engineering Graphics, 14/e Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman © 2012, 2009, 2003, Pearson Higher Education, Upper Saddle River, NJ 07458. • All Rights Reserved.
TOLERANCE Tolerance is the total amount that the feature on the actual part is allowed to vary from what is specified by the drawing or model dimension. E X A M P L E S ALL TOLERANCES ±. 02 INCH UNLESS OTHERWISE NOTED. A Title Block Specifying Tolerances. (Courtesy of Dynojet Research, Inc. ) Technical Drawing with Engineering Graphics, 14/e Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman © 2012, 2009, 2003, Pearson Higher Education, Upper Saddle River, NJ 07458. • All Rights Reserved.
GEOMETRIC BREAKDOWN Engineering structures are composed largely of simple geometric shapes, such as the prism, cylinder, pyramid, cone, and sphere. They may be exterior (positive) or interior (negative) forms. Technical Drawing with Engineering Graphics, 14/e Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman © 2012, 2009, 2003, Pearson Higher Education, Upper Saddle River, NJ 07458. • All Rights Reserved.
LINES USED IN DIMENSIONING Dimension, Extension and Centerlines Technical Drawing with Engineering Graphics, 14/e Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman © 2012, 2009, 2003, Pearson Higher Education, Upper Saddle River, NJ 07458. • All Rights Reserved.
LEADERS A leader is a thin, solid line directing attention to a note or dimension and starting with an arrowhead or dot. For the Best Appearance, Make Leaders • near each other and parallel • across as few lines as possible Don’t Make Leaders • parallel to nearby lines of the drawing • through a corner of the view • across each other • longer than needed • horizontal or vertical Technical Drawing with Engineering Graphics, 14/e Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman © 2012, 2009, 2003, Pearson Higher Education, Upper Saddle River, NJ 07458. • All Rights Reserved.
DRAWING SCALE AND DIMENSIONING Drawing scale is noted in the title block. The drawing should not be scaled for dimensions. (Courtesy of Dynojet Research, Inc. ) Many standard title blocks include a note such as: DO NOT SCALE DRAWING FOR DIMENSIONS Technical Drawing with Engineering Graphics, 14/e Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman © 2012, 2009, 2003, Pearson Higher Education, Upper Saddle River, NJ 07458. • All Rights Reserved.
DIRECTION OF DIMENSION VALUES AND NOTES All dimension values and notes are lettered horizontally to be read from the bottom of the sheet, as oriented by the title block. Technical Drawing with Engineering Graphics, 14/e Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman © 2012, 2009, 2003, Pearson Higher Education, Upper Saddle River, NJ 07458. • All Rights Reserved.
DIMENSION UNITS A note stating ALL MEASUREMENTS IN MILLIMETERS or ALL MEASUREMENTS IN INCHES UNLESS OTHERWISE NOTED is used in the title block to indicate the measurement units… (Courtesy of Dynojet Research, Inc. ) Technical Drawing with Engineering Graphics, 14/e Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman © 2012, 2009, 2003, Pearson Higher Education, Upper Saddle River, NJ 07458. • All Rights Reserved.
MILLIMETER VALUES The millimeter is the commonly used unit for most metric engineering drawings. Oneplace millimeter decimals are used when tolerance limits permit. Two (or more)–place millimeter decimals are used when higher tolerances are required. Technical Drawing with Engineering Graphics, 14/e Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman © 2012, 2009, 2003, Pearson Higher Education, Upper Saddle River, NJ 07458. • All Rights Reserved.
DECIMAL-INCH VALUES Two-place inch decimals are typical when tolerance limits permit. Three or more decimal places are used for tolerance limits in the thousandths of an inch. In two-place decimals, the second place preferably should be an even digit. Technical Drawing with Engineering Graphics, 14/e Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman © 2012, 2009, 2003, Pearson Higher Education, Upper Saddle River, NJ 07458. • All Rights Reserved.
RULES FOR DIMENSION VALUES Good hand-lettering is important for dimension values on sketches. The shop produces according to the directions on the drawing so to save time and prevent costly mistakes, make all lettering perfectly legible. Make all decimal points bold, allowing ample space. When the metric dimension is a whole number, do not show either a decimal point or a zero. When the metric dimension is less than 1 mm, a zero precedes the decimal point. When the decimal-inch dimension is used on drawings, a zero is not used before the decimal point of values less than 1 in. Technical Drawing with Engineering Graphics, 14/e Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman © 2012, 2009, 2003, Pearson Higher Education, Upper Saddle River, NJ 07458. • All Rights Reserved.
DUAL DIMENSIONING AND COMBINATION UNITS Dual dimensioning is used to show metric and decimal-inch dimensions on the same drawing. Two methods of displaying the dual dimensions are: 1. 2. Position Method Bracket Method Technical Drawing with Engineering Graphics, 14/e Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman DIMENSIONS IN () ARE MILLIMETERS © 2012, 2009, 2003, Pearson Higher Education, Upper Saddle River, NJ 07458. • All Rights Reserved.
PLACING AND SHOWING DIMENSIONS LEGIBLY Rules for the placement of dimensions help you dimension your drawings so that they are clear and readable… Fitting Dimension Values in Limited Spaces (Metric Dimensions) Technical Drawing with Engineering Graphics, 14/e Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman © 2012, 2009, 2003, Pearson Higher Education, Upper Saddle River, NJ 07458. • All Rights Reserved.
SUPERFLUOUS DIMENSIONS All necessary dimensions must be shown, but do not give unnecessary or superfluous dimensions. Technical Drawing with Engineering Graphics, 14/e Giesecke, Hill, Spencer, Dygdon, Novak, Lockhart, Goodman © 2012, 2009, 2003, Pearson Higher Education, Upper Saddle River, NJ 07458. • All Rights Reserved.
Скачать презентацию MANUFACTURING PROCESSES CHAPTER NINE OBJECTIVES 1 Describe
ee291a14c5c861606d29376af8a78a89.ppt