Product Design for Manufacture and Assembly Third Edition by Geoffrey, Peter , Winston A 4 88AB0B 1420089277 9781420089271

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Product details:

Table of contents:

1 Introduction

1.1 What Is Design for Manufacture and Assembly?

1.2 History

FIGURE 1.1 Coding system for the automatic feeding and orienting of small rotational parts. (Adapted from Boothroyd, G. Assembly Automation and Product Design, 2nd Ed., CRC Press, Boca Raton, FL, 2005.)

FIGURE 1.2 Examples of design features affecting assembly.

1.3 Implementation of Design for Assembly

1.4 Design for Manufacture

1.5 Producibility Guidelines

FIGURE 1.3 Misleading producibility guideline for the design of sheet metal parts. (From Pahl, G. and Beitz, W. Engineering Design, English Edition, The Design Council, London, 1984. With permission.)

TABLE 1.1 Estimated Costs in Dollars for the Two Examples in Figure 1.3 if 100,000 are Made

FIGURE 1.4 DFMA shortens the design process. (Adapted from Bauer, L. Team Design Cuts Time, Cost, Welding Design Fabrication, September, 1990, p. 35.)

FIGURE 1.5 Who casts the biggest shadow? (Adapted from Munro and Associates, Inc.)

FIGURE 1.6 “Over-the-wall” design, historically the way of doing business. (Adapted from Munro and Associates, Inc.)

FIGURE 1.7 Effects of DFMA and CE on product cost at Hewlett Packard. (Adapted from Williams, R. A. Successful Implementation of Engineering Products and Processes. Van Nostrand, New York, 1994.)

1.6 How Does DFMA Work?

FIGURE 1.8 Original design of the motor drive assembly (dimensions in inches).

TABLE 1.2 Results of DFA Analysis for the Motor Drive Assembly Original Design (Figure 1.8)

FIGURE 1.9 Redesign of the motor drive assembly following DFA analysis.

TABLE 1.3 Results of DFA Analysis for the Motor Drive Assembly Redesign (Figure 1.9)

TABLE 1.4 Comparison of Parts Cost for the Motor Drive Assembly Original Design and Redesign (Purchased Motor and Sensor Subassemblies not Included)

FIGURE 1.10 Typical steps taken in a DFMA study using the DFMA software.

1.7 Falsely Claimed Reasons for Not Implementing DFMA

1.7.1 No Time

1.7.2 Not Invented Here

1.7.3 Ugly baby Syndrome

1.7.4 Low assembly Costs

FIGURE 1.11 DFA analysis can reduce total costs significantly even though assembly costs are small.

1.7.5 Low Volume

1.7.6 We Have Been Doing It for Years

1.7.7 It Is Only Value analysis

1.7.8 DFMA Is Only One among Many Techniques

FIGURE 1.12 Improved assembly efficiency results in increased reliability. (Adapted from Branan, W. Six-Sigma quality and DFA DFMA insight, Boothroyd Dewhurst Inc., 2(1), winter 1991, 1–3.)

1.7.9 DFMA leads to Products that are more Difficult to Service

1.7.10 I Prefer Design Rules

1.7.11 I Refuse to use DFMA

1.8 What Are the Advantages of Applying DFMA during Product Design?

FIGURE 1.13 Responses to a questionnaire presented to IGT engineers prior to the introduction of DFMA. (Adapted from Mikhail, S. Decision-making Process for Implementing DFMA at IGT, International Forum on DFMA, Providence, RI, June 2009.)

FIGURE 1.14 Responses to a questionnaire presented to IGT engineers following the pilot workshop on DFMA. (Adapted from Mikhail, S. Decision-making Process for Implementing DFMA at IGT, International Forum on DFMA, Providence, RI, June 2009.)

1.9 Overall Impact of DFMA on U.S. Industry

TABLE 1.5 Results of 123 Published Case Studies Showing Improvements from the Application of the DFMA Software

FIGURE 1.15 Percentage distribution of DFMA software users by company annual revenue.

FIGURE 1.16 Percentage distribution of DFMA software users by industry.

1.10 Conclusions

FIGURE 1.17 Examples of Problem 1.

FIGURE 1.18 Latch mechanism.

References

2 Selection of Materials and Processes

2.1 Introduction

FIGURE 2.1 Survey of designers’ knowledge of manufacturing processes. (Adapted from Bishop, R. Huge Gaps in Designers’ Knowledge Revealed, Eureka, October 1985.)

FIGURE 2.2 Survey of designers’ knowledge of polymer materials. (Adapted from Bishop, R. Huge Gaps in Designers’ Knowledge Revealed, Eureka, October 1985.)

2.2 General Requirements for Early Materials and Process Selection

2.2.1 Relationship to Process and Operations Planning

2.3 Selection of Manufacturing Processes

FIGURE 2.3 Compatibility between processes and materials.

2.4 Process Capabilities

TABLE 2.1 Capabilities of a Range of Manufacturing Processes

TABLE 2.2 Shape Generation Capabilities of Processes

2.4.1 General Shape Attributes

2.4.2 DFA Compatibility Attributes

2.5 Selection of Materials

2.5.1 Grouping of Materials into Process Compatible Classes

2.5.2 Material Selection by Membership Function Modification

FIGURE 2.4 Membership functions for material and process selection.

FIGURE 2.5 Selection of sintered powder materials by membership function modification. (Adapted from Farris, J. Selection of Processing Sequences and Materials During Early Product Design, Ph.D. Thesis, RI, 1992.)

2.5.3 Material Selection by Dimensionless Ranking

FIGURE 2.6 Elastic modulus for classes of materials plotted on linear scales. (Adapted from Dewhurst, P. and Reynolds, C.R. Journal of Materials Engineering and Performance, 6(3), 53–62, 1997.)

FIGURE 2.7 Elastic modulus for classes of materials plotted on logarithmic scales. (Adapted from Dewhurst, P. and Reynolds, C.R. Journal of Materials Engineering and Performance, 6(3), 53–62, 1997.)

TABLE 2.3 “100 Scale” Values for Young’s Modulus

TABLE 2.4 Largest and Least Material Property Values

TABLE 2.5 Material Database and Derived Parameter Ranking

TABLE 2.6 Derived Parameter D for Best Performance

2.6 Primary Process/Material Selection

FIGURE 2.8 Oven bracket part.

FIGURE 2.9 Process elimination based on four geometric attributes of the part in Figure 2.8.

FIGURE 2.10 Process elimination based on further four attributes of the part in Figure 2.8.

FIGURE 2.11 Final process selection based on geometric attributes of the part in Figure 2.8.

2.7 Systematic Selection of Processes and Materials

2.7.1 Computer-based Primary Process/Material Selection

FIGURE 2.12 Final selection based on process/material combinations of the part shown in Figure 2.8.

FIGURE 2.13 General description of proposed part.

FIGURE 2.14 Material classes compatible with cold-chamber die casting.

2.7.2 Expert Processing Sequence Selector

FIGURE 2.15 Example of membership function for process selection rules.

FIGURE 2.16 Procedure for processing sequence selection.

2.7.3 Economic ranking of Processes

FIGURE 2.17 Seven basic categories of machines’ component parts. (Adapted from PERA, Survey of Machining Requirements in Industry, PERA, Melton Mowbray, UK.)

FIGURE 2.18 Category 2 part—rotational with secondary features.

FIGURE 2.19 Comparison of machining cost estimates. The cost indicated next to each part drawing is the material cost for the part, detailed analysis; □, estimate; , initial estimate.

FIGURE 2.20 Connecting rod.

FIGURE 2.21 Connecting rod costs for different processes and production volumes.

FIGURE 2.22 Cost breakdown for production volume of 100,000.

FIGURE 2.23 Cost comparisons for production volume of 100,000.

FIGURE 2.24 Hollow metal golf driver head construction.

FIGURE 2.25 Electrical instrument support platform.

FIGURE 2.26 Rotor housing.

References

3 Product Design for Manual Assembly

3.1 Introduction

3.2 General Design Guidelines for Manual Assembly

3.2.1 Design Guidelines for Part Handling

FIGURE 3.1 Geometrical features affecting part handling.

FIGURE 3.2 Some other features affecting part handling.

3.2.2 Design Guidelines for insertion and Fastening

FIGURE 3.3 Incorrect geometry can allow a part to jam during insertion.

FIGURE 3.4 Provision of air-relief passages to improve insertion into blind holes.

FIGURE 3.5 Design for ease of insertion—assembly of long-stepped bushing into counterbored hole.

FIGURE 3.6 Provision of chamfers to allow easy insertion.

FIGURE 3.7 Standardize parts.

FIGURE 3.8 Single-axis pyramid assembly.

FIGURE 3.9 Provision of self-locating features to avoid holding down and alignment.

FIGURE 3.10 Design to aid insertion.

FIGURE 3.11 Common fastening methods.

FIGURE 3.12 Insertion from opposite direction requires repositioning of the assembly.

3.3 Development of the Systematic Design for Assembly Methodology

FIGURE 3.13 Power saw (initial design—41 parts, 6.37 min assembly time). (After Ellison, B. and Boothroyd, G. Applying Design for Assembly Handbook to Reciprocating Power Saw and Impact Wrench, Report No. 10, Department of Mechanical Engineering, University of Massachusetts, Amherst, MA, August 1980.)

FIGURE 3.14 Power saw (new design—29 parts, 2.58 min assembly time). (After Ellison, B. and Boothroyd, G. Applying Design for Assembly Handbook to Reciprocating Power Saw and Impact Wrench, Report No. 10, Department of Mechanical Engineering, University of Massachusetts, Amherst, MA, August 1980.)

3.4 Assembly Efficiency

3.5 Classification Systems

FIGURE 3.15 Original classification system for part features affecting manual handling time. (Copyright 1999 Boothroyd Dewhurst, Inc. With permission.)

FIGURE 3.16 Original classification system for part features affecting insertion and fastening. (Copyright 1999 Boothroyd Dewhurst, Inc. With permission.)

Definitions

3.6 Effect of Part Symmetry on Handling Time

FIGURE 3.17 Alpha and beta rotational symmetries for various parts.

FIGURE 3.18 Effect of symmetry on the time required for part handling. Times are average for two individuals and shaded areas represent nonexistent values of the total angle of symmetry.

3.7 Effect of Part Thickness and Size on Handling Time

FIGURE 3.19 Effect of part thickness on handling time.

FIGURE 3.20 Effect of part size on handling time.

3.8 Effect of Weight on Handling Time

3.9 Parts Requiring Two Hands for Manipulation

3.10 Effects of Combinations of Factors

3.11 Effect of Symmetry for Parts That Severely Nest or Tangle and May Require Tweezers for Grasping and Manipulation

FIGURE 3.21 Examples of parts that may require tweezers for handling.

FIGURE 3.22 Effect of symmetry on handling time when parts nest or tangle severely. (Disentangling time is not included.)

3.12 Effect of Chamfer Design on Insertion Operations

FIGURE 3.23 Geometries of peg and hole.

FIGURE 3.24 Effect of clearance on insertion time. (After Ho, C. and Boothroyd, G. Design of chamfers for ease of assembly, Proceedings of the 7th North American Metalworking Conference, May 1979, p. 345.) (For clarity, experimental results are shown for only one case.)

FIGURE 3.25 Points of contact on chamfer and hole.

FIGURE 3.26 Chamfer of constant width.

3.13 Estimation of Insertion Time

EXAMPLE

3.14 Avoiding Jams during Assembly

FIGURE 3.27 Geometry of part and peg.

3.15 Reducing Disc-Assembly Problems

FIGURE 3.28 Geometry of disc and hole.

3.16 Effects of Obstructed Access and Restricted Vision on Insertion of Threaded Fasteners of Various Designs

FIGURE 3.29 Effects of restricted access and restricted vision on the initial engagement of screws. (a) Restricted access and restricted vision; (b) restricted access only.

FIGURE 3.30 Effect of number of threads on time to pick up the tool, engage the screw, tighten the screw, and replace the tool.

FIGURE 3.31 Effect of obstructed access on the time to tighten a nut.

3.17 Effects of Obstructed Access and Restricted Vision on Pop-Riveting Operations

FIGURE 3.32 Effects of obstructed access and restricted vision on the time to insert a pop-rivet. (After Fujita, T., and Boothroyd, G. Data Sheets and Case Study for Manual Assembly, Report No. 16, Department of Mechanical Engineering, University of Massachusetts, Amherst, MA, April 1982.)

3.18 Effects of Holding Down

FIGURE 3.33 Effects of holding down on insertion time. (a) Parts self-locating and pre-aligned; (b) easy-to-align parts; and (c) not easy-to-align parts. (After Yang, S.C. and Boothroyd, G. Data Sheets and Case Study for Manual Assembly, Report No. 15, Department of Mechanical Engineering, University of Massachusetts, Amherst, MA, December 1981.)

EXAMPLE

FIGURE 3.34 Effects of holding down and realignment on insertion time for difficult-to-align parts. (After Yang, S.C. and Boothroyd, G. Data Sheets and Case Study for Manual Assembly, Report No. 15, Department of Mechanical Engineering, University of Massachusetts, Amherst, MA, December 1981.)

3.19 Manual Assembly Database and Design Data Sheets

3.20 Application of the DFA Methodology

FIGURE 3.35 Controller assembly.

FIGURE 3.36 Completed worksheet analysis for the controller assembly.

NUMBER OF ITEMS, RP

HANDLING CODE

HANDLING TIME PER ITEM, TH

INSERTION CODE

INSERTION TIME PER ITEM, TI

TOTAL OPERATION TIME

FIGURES FOR MINIMUM PARTS

3.20.1 Results of the analysis

TABLE 3.1 Design Changes and Associated Savings

FIGURE 3.37 Conceptual redesign of the controller assembly.

FIGURE 3.38 Completed analysis for the controller assembly redesign.

3.21 Further Design Guidelines

FIGURE 3.39 Rearrangement of connected items to improve assembly efficiency and reduce costs.

FIGURE 3.40 Design concept to provide easier access during assembly.

FIGURE 3.41 Design to avoid adjustment during assembly.

FIGURE 3.42 Showing how overconstraint leads to unnecessary complexity in product design.

FIGURE 3.43 Showing how overconstraint leads to redundancy of parts.

3.22 Large Assemblies

3.23 Types of Manual Assembly Methods

FIGURE 3.44 Bench assembly.

FIGURE 3.45 Multistation assembly.

FIGURE 3.46 Modular assembly center.

FIGURE 3.47 Custom assembly layout.

FIGURE 3.48 Flexible assembly layout.

FIGURE 3.49 Multistation assembly of large products.

FIGURE 3.50 Manual assembly methods.

3.24 Effect of Assembly Layout on Acquisition Times

FIGURE 3.51 Acquisition times (s) for items not stored within easy reach of the assembly worker. (Copyright Boothroyd Dewhurst, Inc. 1991.)

FIGURE 3.52 Assumed distribution of parts in custom assembly layout: □, low turnover; ◯, high turnover.

FIGURE 3.53 Effects of distance to storage location on the acquisition and assembly time for small parts.

3.25 Assembly Quality

FIGURE 3.54 Relation between the assembly defect rate and average DFA assembly time. (Adapted from Barkan, P. and Hinckley, C. M. Manufacturing Rev., 6(3), September 1993.)

FIGURE 3.55 Relation between the total DFA assembly time penalty and assembly defect rates per unit. (Adapted from Wright, T. P. Journal of Aeronautical Sciences, 3, pp. 49−73, 1936.)

3.26 Applying learning Curves to the DFA Times

EXAMPLE

FIGURE 3.56 Piston assembly (dimensions in mm).

FIGURE 3.57 Shaft assembly.

FIGURE 3.58 Terminal block.

FIGURE 3.59 Gas meter diaphragm assembly (dimensions in mm).

FIGURE 3.60 Gear box assembly.

FIGURE 3.61 (a) Original diaphragm assembly, and (b) combined diaphragm and clamping ring.

References

4 Electrical Connections and Wire Harness Assembly

4.1 Introduction

FIGURE 4.1 Possible assembly time savings due to the redesign of a commercial control unit.

TABLE 4.1 Labor Content of a Descrambler

TABLE 4.2 Possible Savings through Descrambler Redesign

FIGURE 4.2 Advertisement in PC Magazine, May 26, 1987.

4.2 Wire or Cable Harness Assembly

FIGURE 4.3 Terminology.

FIGURE 4.4 Principal operations.

FIGURE 4.5 Classification of electrical interconnections.

4.3 Types of Electrical Connections

FIGURE 4.6 Types of electrical connections.

4.3.1 Solder Connections

4.3.2 Low-Pressure Connections

FIGURE 4.7 Pin and socket contacts.

FIGURE 4.8 Coupling devices used on circular and rectangular connectors.

4.3.3 High-Pressure Connections

FIGURE 4.9 Wire-wrap termination.

FIGURE 4.10 Attachment of wire, fork lug, and ring lug.

4.4 Types of Wires and Cables

4.5 Preparation and Assembly Times

4.5.1 Preparation

FIGURE 4.11 Results for stripping one wire end. (Adapted from Ong, N. S. and Boothroyd, G. International Journal of Advanced Manufacturing Technology, 6, 155–179, 1991.)

FIGURE 4.12 Results for tinning one wire end. (Adapted from Ong, N. S. and Boothroyd, G. International Journal of Advanced Manufacturing Technology, 6, 155–179, 1991.)

FIGURE 4.13 Results for crimping a terminal to one wire end. (Adapted from Ong, N. S. and Boothroyd, G. International Journal of Advanced Manufacturing Technology, 6, 155–179, 1991.)

FIGURE 4.14 Experimental results for stripping a multiconductor cable: □, experimental. (Adapted from Ong, N. S. and Boothroyd, G. International Journal of Advanced Manufacturing Technology, 6, 155–179, 1991.)

FIGURE 4.15 Manual assembly time for a connector with solder contacts: ○, (7); ◂, (9); □, experimental (total); ▴, Co.2. (Adapted from Ong, N. S. and Boothroyd, G. International Journal of Advanced Manufacturing Technology, 6, 155179, 1991.)

FIGURE 4.16 Manual assembly time for a connector with crimp contacts: ○, experimental (total); ◊, Co. 1; ▴, Co.2. (Adapted from Ong, N. S. and Boothroyd, G. International Journal of Advanced Manufacturing Technology, 6, 155–179, 1991.)

FIGURE 4.17 Manual assembly time for a coaxial connector. (Adapted from Ong, N. S. and Boothroyd, G. International Journal of Advanced Manufacturing Technology, 6, 155–179, 1991)

FIGURE 4.18 Manual assembly time for mass termination of a flat cable.

4.5.2 Assembly and Installation

FIGURE 4.19 Results for point-to-point (direct) wiring: □, experimental; ▴, Co. 2. (Adapted from Ong, N. S. and Boothroyd, G. International Journal of Advanced Manufacturing Technology, 6, 155–179, 1991.)

FIGURE 4.20 Results for dressing a wire into a U-channel: ▴, (9); □, experimental. (Adapted from Ong, N. S. and Boothroyd, G. International Journal of Advanced Manufacturing Technology, 6, 155–179, 1991.)

FIGURE 4.21 Results for laying a flat cable: □, experimental; ◊, Co. 1. (Adapted from Ong, N. S. and Boothroyd, G. International Journal of Advanced Manufacturing Technology, 6, 155–179, 1991.)

FIGURE 4.22 Results for laying a wire or six wires simultaneously onto a harness jig: ○, 1 wire (experimental); □, 6 wires (experimental); ⧫ , 1 (7); ♦, 6 (8); ◊, 1 (8); ▴, 1 (Co. 2.)

FIGURE 4.23 Experimental times for laying wires simultaneously onto a harness jig; ○, lay 1 wire; 2,◊, 3; △, 4; □, 5; ♦, 6. (Adapted from Ong, N. S. and Boothroyd, G. International Journal of Advanced Manufacturing Technology, 6, 155–179, 1991.)

FIGURE 4.24 Results for laying wires simultaneously (from a connector) onto a harness jig; ○, 1 wire (experimental); △, 6 wires (experimental); ♦, 1 wire (8); ▴, 6 wires (8).(Adapted from Ong, N. S. and Boothroyd, G. International Journal of Advanced Manufacturing Technology, 6, 155–179, 1991.)

FIGURE 4.25 Experimental times for laying wires simultaneously (from a connector) onto a harness jig: ○, lay 1 wire; , 2; ◊, 3; △, 4; □, 5; ♦, 6. (Adapted from Ong, N. S. and Boothroyd, G. International Journal of Advanced Manufacturing Technology, 6, 155–179, 1991.)

4.5.3 Securing

FIGURE 4.26 Results for spot tying a harness trunk/branch. (Adapted from Ong, N. S. and Boothroyd, G. International Journal of Advanced Manufacturing Technology, 6, 155–179, 1991.)

FIGURE 4.27 Results for tying a cable tie onto a harness trunk/branch. (Adapted from Ong, N. S. and Boothroyd, G. International Journal of Advanced Manufacturing Technology, 6, 155–179, 1991.)

FIGURE 4.28 Results for lacing a harness trunk/branch. (Adapted from Ong, N. S. and Boothroyd, G. International Journal of Advanced Manufacturing Technology, 6, 155–179, 1991.)

FIGURE 4.29 Results for taping a bundle of wires. (Adapted from Ong, N. S. and Boothroyd, G. International Journal of Advanced Manufacturing Technology, 6, 155–179, 1991.)

FIGURE 4.30 Results for inserting a precut tube or sleeve. (Adapted from Ong, N. S. and Boothroyd, G. International Journal of Advanced Manufacturing Technology, 6, 155–179, 1991.)

FIGURE 4.31 Results for (i) shrinking an inserted tube, and (ii) installing an adhesive cable clamp. (Adapted from Ong, N. S. and Boothroyd, G. International Journal of Advanced Manufacturing Technology, 6, 155–179, 1991.)

FIGURE 4.32 Results for labeling a wire. (Adapted from Ong, N. S. and Boothroyd, G. International Journal of Advanced Manufacturing Technology, 6, 155–179, 1991.)

4.5.4 Attachment

FIGURE 4.33 Results for attachment of bare wire to its mating part. (Adapted from Ong, N. S. and Boothroyd, G. International Journal of Advanced Manufacturing Technology, 6, 155–179, 1991.)

FIGURE 4.34 Results for soldering a bare wire to its mating part. (Adapted from Ong, N. S. and Boothroyd, G. International Journal of Advanced Manufacturing Technology, 6, 155–179, 1991.)

FIGURE 4.35 Results for wire-wrapping around a terminal post. (Adapted from Ong, N. S. and Boothroyd, G. International Journal of Advanced Manufacturing Technology, 6, 155–179, 1991.)

FIGURE 4.36 Results for attachment of a wire terminal to its mating part. (Adapted from Ong, N. S. and Boothroyd, G. International Journal of Advanced Manufacturing Technology, 6, 155–179, 1991.)

FIGURE 4.37 Results for attachment of a wire terminal to its mating part. (Adapted from Ong, N. S. and Boothroyd, G. International Journal of Advanced Manufacturing Technology, 6, 155–179, 1991.)

4.6 Analysis Method

4.6.1 Procedure

FIGURE 4.38 Example harness and run list.

FIGURE 4.39 Data Chart No. 1 for Wire/Cable Preparation and partially completed worksheet.

FIGURE 4.40 Data Chart No. 2 for Wire/Cable Handling and completed worksheet.

FIGURE 4.41 Data Chart No. 3 for Assembly—Insertion and partially completed worksheet.

FIGURE 4.42 Data Chart No. 4 for Dressing and completed worksheet.

FIGURE 4.43 Data Chart No. 5 for Connector Fastening and completed worksheet.

FIGURE 4.44 Data Chart No. 6 for Installation—Wire Fastening and completed worksheet.

FIGURE 4.45 Data Chart No. 7 for Installation—Lug Fastening and completed worksheet.

FIGURE 4.46 Data Chart No. 8 for Installation—Routing and completed worksheet.

FIGURE 4.47 Data Chart No. 9 for Additional Operations—A and partially completed worksheet.

FIGURE 4.48 Data Chart No. 10 for Additional Operations—B and completed worksheet.

FIGURE 4.49 Wire harness summary data.

4.6.2 Case Study

FIGURE 4.50 Current wiring design for a control unit (length in feet).

FIGURE 4.51 Proposed wiring design for a control unit.

TABLE 4.3 Wire Run List for Current Design of Control Unit

TABLE 4.4 Analysis Results for Current Design of Control Unit

TABLE 4.5 Analysis Results for Proposed Design of Control Unit

FIGURE 4.52 Sample harness assembly.

References

5 Design for High-Speed Automatic Assembly and Robot Assembly

5.1 Introduction

FIGURE 5.1 Design change to simplify automatic feeding and orienting.

5.2 Design of Parts for High-Speed Feeding and Orienting

FIGURE 5.2 Effect of required feed rate on feeding cost.

FIGURE 5.3 First digit of geometrical classification of parts for automatic handling. (From Boothroyd, G and Dewhurst, P. Product Design for Assembly Handbook, Boothroyd Dewhurst Inc., Wakefield, Rl, 1986. With permission.)

FIGURE 5.4 Second and third digits of geometrical classification for rotational parts. (From Boothroyd, G. and Dewhurst, P. Product Design for Assembly Handbook, Boothroyd Dewhurst Inc., Wakefield, RI, 1986. With permission.)

FIGURE 5.5 Second and third digits of geometrical classification for nonrotational parts. (From Boothroyd, G. and Dewhurst, P. Product Design for Assembly Handbook, Boothroyd Dewhurst Inc., Wakefield, RI, 1986. With permission.)

5.3 Example

FIGURE 5.6 Sample part

5.4 Additional Feeding Difficulties

FIGURE 5.7 Parts that shingle or overlap on the feeder track.

FIGURE 5.8 Additional relative feeder costs for a selection of feeding difficulties. (From Boothroyd, G. and Dewhurst, P. Product Design for Assembly Handbook, Boothroyd Dewhurst Inc., Wakefield, RI, 1986. With permission.)

5.5 High-Speed Automatic Insertion

FIGURE 5.9 Relative workhead costs Wr for a selection of automatic insertion situations. (From Boothroyd, G. and Dewhurst, P. Product Design for Assembly Handbook, Boothroyd Dewhurst Inc., Wakefield, RI, 1986. With permission.)

5.6 Example

5.7 Analysis of an Assembly

FIGURE 5.10 Simple assembly.

FIGURE 5.11 Completed worksheets for high-speed automatic assembly analysis of the assemblies in Figure 5.10.

5.8 General Rules for Product Design for Automation

FIGURE 5.12 Redesign of part for the ease of assembly. (Adapted from Baldwin, S. P. How to make sure of easy assembly, Tool Manufacturing and Engineering, p. 67, May 1966.)

FIGURE 5.13 Redesign to assist assembly. (Adapted from Tipping, W.V. Component and Product Designfor Mechanized Assembly, Conference on Assembly, Fastening and Joining Techniques and Equipment, PERA, 1965.)

FIGURE 5.14 Various forms of screw points. (Adapted from Tipping, W.V. Component and Product Design for Mechanized Assembly, Conference on Assembly, Fastening and Joining Techniques and Equipment, PERA, 1965.)

FIGURE 5.15 Assembly of three-pin power plug.

FIGURE 5.16 Design of base part for mounting on work carrier.

FIGURE 5.17 The use of tapered pegs to facilitate assembly.

5.9 Design of Parts for Feeding and Orienting

FIGURE 5.18 Examples of redesign to prevent nesting or tangling. (Adapted from Iredale, R. Metalwork Production, April 8, 1964.)

FIGURE 5.19 Provision of asymmetrical features to assist in orientation. (Adapted from Iredale, R. Metalwork Production, April 8, 1964.)

FIGURE 5.20 Less obvious example of a design change to simplify feeding and orienting.

5.10 Summary of Design Rules for High-Speed Automatic Assembly

5.10.1 Rules for Product Design

5.10.2 Rules for the Design of Parts

5.11 Product Design for Robot Assembly

FIGURE 5.21 Classification system and database for a single-station one-arm robot assembly system. (From Boothroyd, G. and Dewhurst, P. Product Design for Assembly Handbook, Boothroyd Dewhurst Inc., Wakefield, RI, 1986. With permission.)

FIGURE 5.22 Classification system and database for a single-station two-arm robot assembly system. (From Boothroyd, G. and Dewhurst, P. Product Design for Assembly Handbook, Boothroyd Dewhurst Inc., Wakefield, RI, 1986. With permission.)

FIGURE 5.23 Classification system and database for a single-station one-arm robot assembly system. (From Boothroyd, G and Dewhurst, P. Product Design for Assembly Handbook, Boothroyd Dewhurst Inc., Wakefield, RI, 1986. With permission.)

5.11.1 Summary of Design Rules for Robot Assembly

FIGURE 5.24 Small parts for feeding and orienting. Note: All dimensions are mm.

FIGURE 5.25 Part for feeding and orienting (dimensions in mm).

FIGURE 5.26 Latch mechanism assembly.

FIGURE 5.27 Part from a motor cycle gearbox coupling.

FIGURE 5.28 Three-part assembly.

FIGURE 5.29 Box assembly. Note: Dimensions in mm.

FIGURE 5.30 Redesigned box assembly. Note: Dimensions in mm.

References

6 Printed Circuit Board Design for Manufacture and Assembly

6.1 Introduction

6.2 Design Sequence for Printed Circuit Boards

6.3 Types of Printed Circuit Boards

6.3.1 Number of Sides

6.3.2 Number of Layers

6.3.3 Board Materials

6.3.4 Device Types

6.3.5 Copper Weight

6.4 Bare Board Manufacture

6.4.1 Basic Bare Board Costs

FIGURE 6.1 Approximate cost per unit area of bare boards. (Adapted from Grezesik, A. Layer Reduction Techniques, Circuit Design, August 1990, p. 21.)

TABLE 6.1 Influence of Number of Layers (nL) on PWB Costs

TABLE 6.2 Increments to Basic Cost Factor for PWBs

EXAMPLE

6.4.2 Number of boards per Panel

6.4.3 Hole Drilling

6.4.4 Optional bare board Processes

6.4.5 Bare board Testing

6.5 Terminology

6.6 Assembly of Printed Circuit Boards

FIGURE 6.2 Various electronic components (not to scale).

6.6.1 Assembly Operations for Through-Hole Printed Circuit boards

6.6.1.1 Automatic Dual Inline Package Insertion

FIGURE 6.3 Automatic dual in-line package (DIP) insertion machine.

FIGURE 6.4 Cut and clinch sequence.

6.6.1.2 AutomaticAxial (VCD) Insertion

FIGURE 6.5 Automatic axial-lead insertion machine.

FIGURE 6.6 Axial-lead components on tape at the insertion head.

FIGURE 6.7 Automatic axial-lead sequencing machine.

6.6.1.3 Automatic Single Inline Package Insertion

6.6.1.4 Automatic Radial Component Insertion

6.6.1.5 Semiautomatic Insertion

FIGURE 6.8 Semiautomatic insertion machine.

6.6.1.6 Manual Insertion

6.6.1.7 Robot Insertion

6.6.1.8 Inspection and Rework

6.6.2 Assembly of Surface-Mounted Devices

FIGURE 6.9 Pick-and-place machine for surface-mounted devices.

6.6.3 Soldering Processes

6.6.3.1 Wave Soldering

6.6.3.2 Reflow Soldering

TABLE 6.3 Comparison of Solder Paste Types

6.6.4 Other Assembly Processes

6.6.4.1 Cleaning

6.6.4.2 Rework

6.6.4.3 Board Testing

6.6.5 Assembly Sequences for Printed Circuit boards

FIGURE 6.10 Assembly sequences for single technology boards (type 1).

FIGURE 6.11 Assembly sequence for type-2 board—through-hole devices topside and surface-mounted devices bottom side.

FIGURE 6.12 Assembly sequence for type-3 boards—through hole and surface-mounted topside and surface-mounted devices bottom side.

6.7 Estimation of PCB Assembly Costs

6.7.1 Component Insertion Costs

TABLE 6.4 Insertion Times and Costs for Through-Hole Components

TABLE 6.5 Insertion Times and Costs for Surface-Mounted Components

TABLE 6.6 Average Insertion Fault Rates for Through-Hole Components

TABLE 6.7 Average Insertion Fault Rates for Surface-Mounted Components

TABLE 6.8 Rework Times for Through-Hole Components

TABLE 6.9 Rework Times for Surface-Mounted Components

6.7.1.1 Insertion Cost

6.7.1.2 Setup Cost

6.7.1.3 Rework Cost

6.7.1.4 Programming Cost

6.7.2 Worksheet for Printed Circuit board assembly Costs

TABLE 6.10 Basic Data for PCB Assembly Worksheet

TABLE 6.11 Worksheet for Printed Circuit Board Assembly

6.7.3 Example

TABLE 6.12 Completed Worksheet

TABLE 6.13 Video Board Design Parameters

TABLE 6.14 Parts List for the Video Board

TABLE 6.15 Parts List for Small PC Board

6.8 Case Studies in PCB Assembly

6.8.1 Measuring instrument Connector board

FIGURE 6.13 Layout of components for a small PCB. (a) Upper side; (b) lower side.

FIGURE 6.14 Effect of production volume on costs for PCB in Figure 6.13.

6.8.2 Power Supply

FIGURE 6.15 Components in a small power-supply board. (From Boothroyd, G. and Dewhurst, P. Product Design for Assembly, Boothroyd Dewhurst, Inc., Wakefield, RI, 1987. With permission.)

FIGURE 6.16 Breakdown of assembly costs for small power supply.

6.9 Glossary of Terms

References

7 Design for Machining

7.1 Introduction

7.2 Machining Using Single-Point Cutting Tools

FIGURE 7.1 Cylindrical turning.

FIGURE 7.2 Lathe operations: (a) Cylindrical. turning, (b) facing, (c) boring, (d) external threading, (e) parting or cut-off. (Adapted from Boothroyd, G. and Knight,. W.A. Fundamentals of Machining and Machine Tools. 3rd ed. CRC Press, Boca Raton, FL, 2006.)

FIGURE 7.3 Boring on a horizontal-boring machine. (Adapted from Boothroyd, G. and Knight, W.A. Fundamentals of Machining and Machine Tools. 3rd ed. CRC Press, Boca Raton, FL, 2006.)

FIGURE 7.4 Facing on a horizontal-boring machine. (Adapted from Boothroyd, G. and Knight, W.A. Fundamentals of Machining and Machine Tools. 3rd ed. CRC Press, Boca Raton, FL, 2006.)

FIGURE 7.5 Production of a flat surface on a planer. (Adapted from Boothroyd, G. and Knight, W.A. Fundamentals of Machining and Machine Tools. 3rd ed. CRC Press, Boca Raton, FL, 2006.)

7.3 Machining Using Multipoint Tools

FIGURE 7.6 Drilling on a drill press. (Adapted from Boothroyd, G. and Knight, W.A. Fundamentals of Machining and Machine Tools. 3rd ed. CRC Press, Boca Raton, FL, 2006.)

FIGURE 7.7 Some drill-press operations, (a) center drilling, (b) reaming, (c) spot-facing. (Adapted from Boothroyd, G. and Knight, W.A. Fundamentals of Machining and Machine Tools. 3rd ed. CRC Press, Boca Raton, FL, 2006.)

FIGURE 7.8 Slab milling on a knee-type horizontal milling machine. (Adapted from Boothroyd, G. and Knight, W.A. Fundamentals ofMachining and Machine Tools. 3rd ed. CRC Press, Boca Raton, FL, 2006.)

FIGURE 7.9 Relative motion between a slab-milling cutter and the workpiece during machining time. (Adapted from Boothroyd, G. and Knight, W.A. Fundamentals of Machining and Machine Tools. 3rd ed. CRC Press, Boca Raton, FL, 2006.)

FIGURE 7.10 Some horizontal-milling operations, (a) Form cutting, (b) slotting, (c) straddle milling, (d) angular milling. (Adapted from Boothroyd, G. and Knight, W.A. Fundamentals of Machining and Machine Tools. 3rd ed. CRC Press, Boca Raton, FL, 2006.)

FIGURE 7.11 Face milling on a vertical-milling machine. (Adapted from Boothroyd, G. and Knight, W.A. Fundamentals of Machining and Machine Tools. 3rd ed. CRC Press, Boca Raton, FL, 2006.)

FIGURE 7.12 Relative motion between the face-milling cutter and the workpiece during machining time. (Adapted from Boothroyd, G. and Knight, W.A. Fundamentals of Machining and Machine Tools. 3rd ed. CRC Press, Boca Raton, FL, 2006.)

FIGURE 7.13 Some vertical-milling machine operations, (a) horizontal surface, (b) slot, (c) dovetail, (d) T slot. Adapted from Boothroyd, G. and Knight, W.A. Fundamentals of Machining and Machine Tools. 3rd ed. CRC Press, Boca Raton, FL, 2006.)

FIGURE 7.14 Broaching on a vertical-broaching machine. (Adapted from Boothroyd, G. and Knight, W.A. Fundamentals of Machining and Machine Tools. 3rd ed. CRC Press, Boca Raton, FL, 2006.)

FIGURE 7.15 Methods of broaching a hole, (a) Pull broach; (b) Push broach. (Adapted from Boothroyd, G. and Knight, W.A. Fundamentals ofMachining and Machine Tools. 3rd ed. CRC Press, Boca Raton, FL, 2006.)

FIGURE 7.16 Tapping. (Adapted from Boothroyd, G. and Knight, W.A. Fundamentals of Machining and Machine Tools. 3rd ed. CRC Press, Boca Raton, FL, 2006.)

7.4 Machining Using Abrasive Wheels

FIGURE 7.17 Common shapes of abrasive wheels, (a) Cylindrical, (b) disc, (c) cup. (Adapted from Boothroyd, G. and Knight, W. A. Fundamentals of Machining and Machine Tools. 3rd ed. CRC Press, Boca Raton, FL, 2006.)

FIGURE 7.18 Surface grinding on a horizontal-spindle surface grinder. (Adapted from Boothroyd, G. and Knight, W.A. Fundamentals of Machining and Machine Tools. 3rd ed. CRC Press, Boca Raton, FL, 2006.)

FIGURE 7.19 Horizontal-spindle surface-grinding operations, (a) Traverse grinding; (b) plunge grinding. (Adapted from Boothroyd, G. and Knight, W.A. Fundamentals of Machining and Machine Tools. 3rd ed. CRC Press, Boca Raton, FL, 2006.)

FIGURE 7.20 Surface grinding on a vertical-spindle surface grinder. (Adapted from Boothroyd, G and Knight, W.A. Fundamentals ofMachining and Machine Tools. 3rd ed. CRC Press, Boca Raton, FL, 2006.)

FIGURE 7.21 Cylindrical grinding. (Adapted from Boothroyd, G. and Knight, W.A. Fundamentals of Machining and Machine Tools. 3rd ed. CRC Press, Boca Raton, FL, 2006.)

FIGURE 7.22 Cylindrical-grinding operations, (a) Traverse grinding; (b) plunge grinding. (Adapted from Boothroyd, G. and Knight, W.A. Fundamentals of Machining and Machine Tools. 3rd ed. CRC Press, Boca Raton, FL, 2006.)

FIGURE 7.23 Internal grinding. (Adapted from Boothroyd, G. and Knight, W.A. Fundamentals of Machining and Machine Tools. 3rd ed. CRC Press, Boca Raton, FL, 2006.)

FIGURE 7.24 Internal-grinding operations, (a) Traverse grinding; (b) plunge grinding. (Adapted from Boothroyd, G. and Knight, W.A. Fundamentals ofMachining and Machine Tools. 3rd ed. CRC Press, Boca Raton, FL, 2006.)

7.5 Standardization

7.6 Choice of Work Material

7.7 Shape of Work Material

TABLE 7.1 Standard Material Shapes and Ranges of Sizes

FIGURE 7.25 Basic component shapes, (a) Rotational; (b) nonrelational. (Adapted from Boothroyd, G. and Knight, W.A. Fundamentals ofMachining and Machine Tools. 3rd ed. CRC Press, Boca Raton, FL, 2006.)

7.8 Machining Basic Component Shapes

7.8.1 Disc-Shaped Rotational Components (L/D ≤ 0.5)

FIGURE 7.26 Some ways of machining a disc-shaped workpiece. (Adapted from Boothroyd, G. and Knight, W.A. Fundamentals of Machining and Machine Tools. 3rd ed. CRC Press, Boca Raton, FL, 2006.)

FIGURE 7.27 Parting finished components from bar stock. (Adapted from Boothroyd, G. and Knight, W.A. Fundamentals of Machining and Machine Tools. 3rd ed. CRC Press, Boca Raton, FL, 2006.)

FIGURE 7.28 Machining of components stepped to both ends. (Adapted from Boothroyd, G. and Knight, W.A. Fundamentals of Machining and Machine Tools. 3rd ed. CRC Press, Boca Raton, FL, 2006.)

FIGURE 7.29 Rounded corners and chamfers. (Adapted from Boothroyd, G. and Knight, W.A. Fundamentals of Machining and Machine Tools. 3rd ed. CRC Press, Boca Raton, FL, 2006.)

FIGURE 7.30 Drilling a pattern of auxiliary holes.

7.8.2 Short, Cylindrical Components (0.5 < L/D < 3)

FIGURE 7.31 Machining components from bar stock, (a) Components that can be parted off complete; (b) components that cannot be parted off complete. (Adapted from Boothroyd, G. and Knight, W.A. Fundamentals of Machining and Machine Tools. 3rd ed. CRC Press, Boca Raton, FL, 2006.)

7.8.3 Long, Cylindrical Rotational Components (L/D > 3)

FIGURE 7.32 Machining of a keyway. (a) Vertical milling, (b) horizontal milling. (Adapted from Boothroyd, G. and Knight, W.A. Fundamentals of Machining and Machine Tools. 3rd ed. CRC Press, Boca Raton, FL, 2006.)

FIGURE 7.33 Difficulties arising when nonconcentric cylindrical surfaces are specified, (a) Impossible to machine, (b) difficult to machine, (c) can be machined on a drill press. (Adapted from Boothroyd, G. and Knight, W.A. Fundamentals of Machining and Machine Tools. 3rd ed. CRC Press, Boca Raton, FL, 2006.)

FIGURE 7.34 Design features to avoid in rotational parts, (a) Special drill required to machine radial hole, (b) impossible to machine internal recess. (Adapted from Boothroyd, G. and Knight, W.A. Fundamentals ofMachining and Machine Tools. 3rd ed. CRC Press, Boca Raton, FL, 2006.)

FIGURE 7.35 Machined screw threads on stepped components, (a) Impossible to machine, (b) good design with run-out groove. (Adapted from Boothroyd, G. and Knight, W.A. Fundamentals ofMachining and Machine Tools. 3rd ed. CRC Press, Boca Raton, FL, 2006.)

7.8.4 Nonrotational Components (A/B ≤ 3, A/C≥ 4)

FIGURE 7.36 Milling external shape of flat components, (a) Vertical milling (plan view), (b) horizontal milling (front view). (Adapted from Boothroyd, G. and Knight, W.A. Fundamentals of Machining and Machine Tools. 3rd ed. CRC Press, Boca Raton, FL, 2006.)

FIGURE 7.37 Machining of principal bores in nonrotational workpieces. (a) Lathe, (b) vertical borer, (c) jig borer. (Adapted from Boothroyd, G. and Knight, W.A. Fundamentals of Machining and Machine Tools. 3rd ed. CRC Press, Boca Raton, FL, 2006.)

FIGURE 7.38 Plane-surface machining of flat components, (a) Shaping or planing, (b) horizontal milling, (c) vertical milling. (Adapted from Boothroyd, G. and Knight, W.A. Fundamentals of Machining and Machine Tools. 3rd ed. CRC Press, Boca Raton, FL, 2006.)

7.8.5 Long, Nonrotational Components (A/B > 3)

7.8.6 Cubic, Nonrotational Components (A/B < 3, A/C < 4)

FIGURE 7.39 Milling outer surface of a cubic workpiece. (Adapted from Boothroyd, G. and Knight, W.A. Fundamentals of Machining and Machine Tools. 3rd ed. CRC Press, Boca Raton, FL, 2006.)

FIGURE 7.40 Milling a pocket in a blocklike cubic workpiece. (Adapted from Boothroyd, G. and Knight, W.A. Fundamentals of Machining and Machine Tools. 3rd ed. CRC Press, Boca Raton, FL, 2006.)

FIGURE 7.41 Design features to avoid in nonrotational components. (Adapted from Boothroyd, G. and Knight, W.A Fundamentals ofMachining and Machine Tools. 3rd ed. CRC Press, Boca Raton, FL, 2006.)

FIGURE 7.42 Design of blind holes. (Adapted from Boothroyd, G. and Knight, W.A. Fundamentals of Machining and Machine Tools. 3rd ed. CRC Press, Boca Raton, FL, 2006.)

7.9 Assembly of Components

FIGURE 7.43 Components that cannot be assembled. (Adapted from Boothroyd, G. and Knight, W. A. Fundamentals of Machining and Machine Tools. 3rd ed. CRC Press, Boca Raton, FL, 2006.)

7.10 Accuracy and Surface Finish

FIGURE 7.44 General range of surface roughness obtainable by various machining operations. (Adapted from Boothroyd, G and Knight, W.A. Fundamentals of Machining and Machine Tools. 3rd ed. CRC Press, Boca Raton, FL, 2006.)

FIGURE 7.45 Effect of specified surface roughness on production costs in a turning operation, where the corner radius rε = 0.03 in.(0762 mm), the rotational frequency of the workpiece nw = 200 rpm (3.33 s−1), and the length of the workpiece lw = 34 in. (864 mm). (Adapted from Boothroyd, G. and Knight, W.A. Fundamentals of Machining and Machine Tools. 3rd ed. CRC Press, Boca Raton, FL, 2006.)

FIGURE 7.46 Surfaces that can readily be finish-ground, (a) Surface grinding, (b) cylindrical grinding, (c) internal grinding. (Adapted from Boothroyd, G. and Knight, W.A. Fundamentals of Machining and Machine Tools. 3rd ed. CRC Press, Boca Raton, FL, 2006.)

7.11 Summary of Design Guidelines

7.12 Cost Estimating for Machined Components

7.12.1 Material Cost

TABLE 7.2 Approximate Costs in Dollars per Pound for Various Metals

7.12.2 Machine loading and Unloading

TABLE 7.3 Loading and Unloading Times (s) versus Workpiece Weight

7.12.3 Other Nonproductive Costs

TABLE 7.4 Some Nonproductive Times for Common Machine Tools

7.12.4 Handling between Machines

7.12.5 Material Type

7.12.6 Machining Costs

TABLE 7.5 Allowances for Tool Approach

TABLE 7.6 Machining Data

7.12.7 Tool Replacement Costs

7.12.8 Machining Data

FIGURE 7.47 Relation between horsepower and workpiece weight for some machine tools.

TABLE 7.7 Machining Data for Milling Operations

7.12.9 Rough grinding

TABLE 7.8 Machining Data for Horizontal-Spindle Surface Grinding

7.12.10 Finish Grinding

7.12.11 Allowance for Grinding Wheel Wear

EXAMPLE

7.12.12 Allowance for Spark-Out

7.12.13 Examples

FIGURE 7.48 Relation between cost and workpiece weight for some machine tools.

FIGURE 7.49 Turned component. Batch size, 1500; workpiece, 3.25 in. dia. × 10.25 in. long; material, low carbon free-machining steel.

7.12.14 Machining Cost Estimating Worksheet

TABLE 7.9 Machining Cost Analysis Worksheet

TABLE 7.10 Summary of Data and Calculations for Cost Estimation Worksheet

EXAMPlE

FIGURE 7.50 Simple stepped rotational part for cost estimating example.

TABLE 7.11 Machining Cost Analysis Worksheet for steepped shaft (Figure 7.50)

7.12.15 Approximate Cost Models for Machined Components

FIGURE 7.51 Effect of component size on rough machining, finish machining, and nonproductive times per unit volume.

FIGURE 7.52 Effect of component size on total cost for machining a free-machining steel workpiece (cost 50 cents/lb) with an inserted carbide tool.

FIGURE 7.53 Costs (dollars) for a series of turned components.

FIGURE 7.54 Alternative cylinder assembly designs. Alternative cylinder assembly designs.

FIGURE 7.55 Alternative milled end cover designs.

FIGURE 7.56 Mild steel turned part. Note: Dimensions in inches.

FIGURE 7.57 Aluminum alloy part produced on a small machining center. Note: Dimensions in inches; Material: alluminium alloy; Bactch size: 200.

References

8 Design for Injection Molding

8.1 Introduction

8.2 Injection Molding Materials

TABLE 8.1 Commonly Used Polymers in Injection Molding

8.3 Molding Cycle

FIGURE 8.1 Injection molding cycle.

8.3.1 Injection or Filling Stage

8.3.2 Cooling or Freezing Stage

8.3.3 Ejection and Resetting Stage

8.4 Injection Molding Systems

FIGURE 8.2 Injection molding system.

8.4.1 Injection unit

8.4.2 Clamp unit

8.5 Injection Molds

8.5.1 Mold Construction and Operation

FIGURE 8.3 Injection mold.

8.5.2 Mold Types

FIGURE 8.4 Two-plate injection mold.

FIGURE 8.5 Angle-pin-activated side-pull.

FIGURE 8.6 Unscrewing mold.

8.5.3 Sprue, Runner, and Gates

8.6 Molding Machine Size

Table 8.2 Runner Volumes (Du Pont)

EXAMPLE

TABLE 8.3 Processing Data for Selected Polymers

TABLE 8.4 Injection Molding Machines

8.7 Molding Cycle Time

8.7.1 Injection Time

EXAMPLE

8.7.2 Cooling Time

FIGURE 8.7 Wall cooling between cavity and core surfaces.

EXAMPLE

8.7.3 Mold resetting

TABLE 8.5 Machine Clamp Operation Times (s)

Example: Resetting Time

8.8 Mold Cost Estimation

8.8.1 Mold Base Costs

FIGURE 8.8 Principal mold base cost driver.

EXAMPLE

8.8.2 Cavity and Core Manufacturing Costs

FIGURE 8.9 Surface segments of plain conical components. Note: All dimensions in millimeters.

TABLE 8.6 Percentage Increases for Different Appearance Levels

TABLE 8.7 Percentage Increases for Tolerance

TABLE 8.8 Parting Surface Classification

8.9 Mold Cost Point System

EXAMPLE

FIGURE 8.10 Approximate mold cost curves for increasing projected area, Ap. (Costs for class of typical parts as described in the text with $40/h mold-making rate.)

8.10 Estimation of the Optimum Number of Cavities

FIGURE 8.11 National average injection molding machine rates.

FIGURE 8.12 Relative plate cavity area.

8.11 Design Example

FIGURE 8.13 Heater core cover.

FIGURE 8.14 Proposed redesign of heater core cover.

8.12 Insert Molding

8.13 Design Guidelines

8.14 Assembly Techniques

FIGURE 8.15 Ultrasonic welding joint design by Du Pont.

FIGURE 8.16 Section of assembly illustrating annular snap-fit cover.

FIGURE 8.17 Cantilever snap fit elements, (a) Undercuts formed by core rods; (b) undercuts formed by side-pulls.

FIGURE 8.18 Annular ring design.

FIGURE 8.19 Pneumatic piston assembly base part.

FIGURE 8.20 Pair of identical injection-molded hose clamps.

References

9 Design for Sheet Metalworking

9.1 Introduction

TABLE 9.1 Standard U.S. Sheet Metal Thickness

TABLE 9.2 Sheet Metal Properties and Typical Costs

9.2 Dedicated Dies and Pressworking

9.2.1 Individual Dies for Profile Shearing

FIGURE 9.1 Die set.

FIGURE 9.2 Mechanical press.

FIGURE 9.3 Cut-off part design.

FIGURE 9.4 Part-off part design.

FIGURE 9.5 Die elements of cut-off and part-off dies, (a) cut-off die, (b) part-off die.

FIGURE 9.6 Blanking die.

FIGURE 9.7 Part design for cut-off and drop-through.

9.2.2 Cost of Individual Shearing Dies

FIGURE 9.8 Basic manufacturing points for blanking die.

FIGURE 9.9 Area correction factor for die manufacturing points.

FIGURE 9.10 Total manufacturing points for blanking die.

EXAMPLE

FIGURE 9.11 Sheet metal part (dimensions in mm), (a) blanking design, (b) part-off design.

9.2.3 Individual Dies for Piercing Operations

FIGURE 9.12 Standard punch shapes.

EXAMPLE

FIGURE 9.13 Part design with three punched holes.

9.2.4 Individual Dies for Bending Operations

FIGURE 9.14 Basic bending tools, (a) v-die, (b) Wiper die.

FIGURE 9.15 Basic methods of producing multiple bends, (a) u-die, (b) z-die.

FIGURE 9.16 Multiple bends produced in one die.

FIGURE 9.17 Part design requiring two bending dies.

FIGURE 9.18 Wiper-die arrangement to produce bend b in Figure 9.17.

EXAMPLE

9.2.5 Individual Dies for Deep Drawing

FIGURE 9.19 Deep drawn rectangular component.

FIGURE 9.20 Tooling elements for deep drawn rectangular component.

FIGURE 9.21 Part produced by deep drawing and two redrawing operations.

FIGURE 9.22 Section view of ironing operation.

TABLE 9.3 Material Properties for Deep Drawing

EXAMPLE

FIGURE 9.23 Deep cylindrical drawn part.

9.2.6 Miscellaneous Features

FIGURE 9.24 Shallow formed and embossed regions of sheet metal part.

9.2.7 Progressive Dies

FIGURE 9.25 Multistation die operation with strip feed.

9.3 Press Selection

FIGURE 9.26 Shearing operation.

TablE 9.4 Single-Action Presses

FIGURE 9.27 Wiper die bending operation.

9.3.1 Cycle Times

EXAMPLE

USING INDIVIDUAL DIES

USING PROGRESSIVE DIE

9.4 Turret Pressworking

FIGURE 9.28 Turret press.

FIGURE 9.29 Layout of parts produced by turret press; (- — -) Subsequent bend lines.

FIGURE 9.30 Turret press radius tools.

TABLE 9.5 Typical Turret Press Manufacturing Characteristics

FIGURE 9.31 Part geometry that requires nibbling or profile cutting.

TABLE 9.6 Plasma and Laser Cutting Speeds for 3 mm Thick Material

9.5 Press Brake Operations

TABLE 9.7 Typical Press Brake Manufacturing Characteristics

EXAMPLE

9.6 Design Rules

FIGURE 9.32 Critical dimensions in the design of a sheet metal blank.

FIGURE 9.33 Lanced and formed bridge.

FIGURE 9.34 Lanced and formed louver.

FIGURE 9.35 Formed hole flange.

FIGURE 9.36 Cross section of rib.

FIGURE 9.37 Punched slots adjacent to a bend.

FIGURE 9.38 Design changes of a three-hole bracket for minimization of manufactured scrap.

FIGURE 9.39 Stainless steel barbeque spatula blade.

FIGURE 9.40 Layout of spatula blades to minimize manufacturing scrap.

FIGURE 9.41 Machine support bracket.

FIGURE 9.42 Deep drawn aluminum rotor–primary shape.

FIGURE 9.43 Deep drawn aluminum rotor-finished part.

References

10 Design for Die Casting

10.1 Introduction

10.2 Die-Casting Alloys

TABLE 10.1 Commonly Used Die-Casting Alloys

TABLE 10.2 Typical Die Life Values per Cavity

10.3 Die-Casting Cycle

10.4 Die-Casting Machines

10.4.1 Die-Mounting and Clamping Systems

10.4.2 Metal-Pumping and injection Systems

10.4.3 Hot-Chamber Machines

FIGURE 10.1 Hot-chamber injection system.

TABLE 10.3 Hot-Chamber Die-Casting Machines

10.4.4 Cold-Chamber Machines

FIGURE 10.2 Cold-chamber die-casting machine elements.

TABLE 10.4 Cold-Chamber Die-Casting Machines

10.5 Die-Casting Dies

FIGURE 10.3 Die for cold-chamber die-casting machine.

10.5.1 Trimming Dies

10.6 Finishing

TABLE 10.5 Costs of Common Finishing Processes

10.7 Auxiliary Equipment for Automation

FIGURE 10.4 Simple mechanical ladle for cold-chamber machine.

10.8 Determination of the Optimum Number of Cavities

FIGURE 10.5 Capital costs of die-casting machines.

EXAMPLE

FIGURE 10.6 Restricted layout of cavities with two side-pulls.

10.9 Determination of Appropriate Machine Size

10.9.1 Required Machine Clamp Force

FIGURE 10.7 Hot-chamber die casting before and after trimming.

TABLE 10.6 Typical Cavity Pressures in Die Casting

10.9.2 Shot Volume and Material Cost per Part

10.9.3 Dimensional Machine Constraints

FIGURE 10.8 Layout of two-cavity die.

EXAMPLE

10.10 Die Casting Cycle Time Estimation

10.10.1 Ladling of Molten Metal

10.10.2 Metal injection

TABLE 10.7 Typical Die Casting Thermal Properties

10.10.3 Metal Cooling

EXAMPLE

EXAMPLE

10.10.4 Part extraction and Die lubrication

EXAMPLE

TABLE 10.8 Lubricant Application Times for Die Casting (Seconds) and Required Cycles per Lubrication

EXAMPLE

10.10.5 Trimming Cycle Time

10.11 Die Cost Estimation

10.11.1 Die Set Costs

FIGURE 10.9 Relative cost of die-casting die sets.

10.11.2 Cavity and Core Costs

TABLE 10.9 Surface Finish Effect on Point Score

10.11.3 Trim Die Costs

EXAMPLE

FIGURE 10.10 Approximate casting die cost curves for increasing projected area, Ap. (Costs for class of typical parts as described in the text with $40/h die making rate.)

FIGURE 10.11 Approximate trim die cost curves for increasing plan area, LW. (Costs are for single trim plane with $40/h die making rate; additional costs must be added for standard holes, different trim levels or side action.)

10.12 Assembly Techniques

10.13 Design Principles

FIGURE 10.12 Rotor assembly housing.

FIGURE 10.13 Support platform.

References

11 Design for Powder Metal Processing

11.1 Introduction

FIGURE 11.1 Material utilization for basic shape-producing processes. (Adapted from Kloos, K.H., VDI Berichte, No. 77, p. 193, 1977.)

FIGURE 11.2 Energy utilization per unit part weight for basic shape-producing processes. (Adapted from Kloos, K.H., VDI Berichte, No. 77, p. 193, 1977.)

11.2 Main Stages in the Powder Metallurgy Process

FIGURE 11.3 Main processing stages for sintered powder parts. (Adapted from Mosca, E., Powder Metallurgy: Criteria for Design and Inspection, Associozone Industriali Metallugici Meccanici Affini, Turin, 1984.)

11.2.1 Mixing

11.2.2 Compaction

11.2.3 Sintering

11.3 Secondary Manufacturing Stages

FIGURE 11.4 Secondary processing stages for sintered powder parts. (Adapted from Mosca, E., Powder Metallurgy: Criteria for Design and Inspection, Associozone Industriali Metallugici Meccanici Affini, Turin, 1984.)

11.3.1 Repressing and Resintering

11.3.2 Sizing and Coining

11.3.3 Infiltration

11.3.4 Impregnation

11.3.5 Resin Impregnation

11.3.6 Heat Treatment

11.3.7 Machining

11.3.8 Tumbling and Deburring

11.3.9 Plating and Other Surface Treatments

11.3.10 Steam Treating

11.3.11 Assembly Processes

11.4 Compaction Characteristics of Powders

FIGURE 11.5 Basic compaction sequence for powder metal parts. (Adapted from MPIF, Powder Metallurgy Design Manual, 3rd ed., Metal Powder Industries Federation, Princeton, NJ, 2007.)

TABLE 11.1 Extract from Data on Standard Iron-Based Materials

11.4.1 Powder Compaction Mechanics

FIGURE 11.6 Density distribution in a nickel powder specimen compacted from one side only (densities in gm/cc). (Adapted from Bradbury, S., Powder Metallurgy Equipment Manual, Metal Powder Industries Federation, Princeton, NJ, 1986.)

FIGURE 11.7 Density variations during two-sided compaction.

FIGURE 11.8 Density variations in a two-level part. (Adapted from Bradbury, S., Powder Metallurgy Equipment Manual, Metal Powder Industries Federation, Princeton, NJ, 1986.)

11.4.2 Compression Characteristics of Metal Powders

FIGURE 11.9 Typical compression curves for metal powders. (Adapted from Bradbury, S., Powder Metallurgy Equipment Manual, Metal Powder Industries Federation, Princeton, NJ, 1986.)

TABLE 11.2 Typical Compaction Pressures for Powder Materials

FIGURE 11.10 Compression curves for single compaction and repressing of iron powder.

FIGURE 11.11 Correction of compaction pressures for increased part thickness.

11.4.3 Powder Compression Ratio

FIGURE 11.12 Fill height and ejection stroke during powder compaction. (Adapted from Bradbury, S., Powder Metallurgy Equipment Manual, Metal Powder Industries Federation, Princeton, NJ, 1986.)

11.5 Tooling for Powder Compaction

FIGURE 11.13 Typical compaction tool elements for a multilevel part. (Adapted from Bradbury, S., Powder Metallurgy Equipment Manual, Metal Powder Industries Federation, Princeton, NJ, 1986.)

11.5.1 Compaction Dies

FIGURE 11.14 Compaction die insert dimensions.

11.5.2 Punches for Compaction

11.5.3 Core Rods for Through Holes

11.5.4 Die Accessories

11.6 Presses for Powder Compaction

11.6.1 Factors in Choosing the Appropriate Press

TABLE 11.3 Data on a Range of Typical Compaction Presses

11.6.1.1 Punch Motions

11.6.1.2 Load Required

11.6.1.3 Fill Height

11.6.1.4 Ejection Stroke

11.6.1.5 Maximum Die Diameter

11.6.2 Presses for Coining, Sizing, and Repressing

TABLE 11.4 Data on a Range of Typical Coining and Sizing Presses

11.7 Form of Powder Metal Parts

FIGURE 11.15 Typical powder metal parts.

FIGURE 11.16 Levels in powder metal parts.

TABLE 11.5 Press Requirements for MPIF Parts Classification [1]

11.7.1 Profile Complexity

11.8 Sintering Equipment Characteristics

TABLE 11.6 Typical Sintering Temperatures and Times for Different Materials

11.8.1 Sintering Equipment

TABLE 11.7 Typical Operating Temperatures for Sintering Furnaces

11.8.1.1 Continuous-Flow Furnaces

FIGURE 11.17 Continuous-flow furnaces. (Adapted from Bradbury, S., Powder Metallurgy Equipment Manual, Metal Powder Industries Federation, Princeton, NJ, 1986.)

TABLE 11.8 Data on Typical Continuous Furnaces

FIGURE 11.18 Temperature profile for continuous-flow furnace. (Adapted from Bradbury, S., Powder Metallurgy Equipment Manual, Metal Powder Industries Federation, Princeton, NJ, 1986.)

11.8.1.2 Batch Furnaces

FIGURE 11.19 Bell-type batch furnace. (Adapted from Bradbury, S., Powder Metallurgy Equipment Manual, Metal Powder Industries Federation, Princeton, NJ, 1986.)

FIGURE 11.20 Heating and cooling cycle for a vacuum batch furnace. (Adapted from Bradbury, S., Powder Metallurgy Equipment Manual, Metal Powder Industries Federation, Princeton, NJ, 1986.)

TABLE 11.9 Data for Typical Batch Sintering Furnaces

11.9 Materials for Powder Metal Processing

TABLE 11.10 Main Classes of Powder Materials

TABLE 11.11 Data for MPIF Standard Iron and Carbon Steel Powder Metal Materials

TABLE 11.12 Data for MPIF Standard Copper-Infiltrated Steels

TABLE 11.13 Portion of Data for MPIF Standard Self-Lubricating Bearing Materials

11.10 Contributions to Basic Powder Metallurgy Manufacturing Costs

FIGURE 11.21 Cost related to increased part material properties. (Adapted from Fumo, A., Early Cost Estimating for Sintered Powder Metal Components, M.S. Thesis, Department of Industrial and Manufacturing Engineering, University of Rhode Island, Kingston, 1988.)

11.10.1 Material Costs

EXAMPLE

FIGURE 11.22 Typical two-level powder metal part.

11.10.2 Compacting Costs

11.10.2.1 Press Selection

EXAMPLE

11.10.2.2 Setup Cost

11.10.3 Compaction Tooling Costs

11.10.3.1 Initial Tooling Costs

11.10.3.2 Tool Material Costs

EXAMPLE

11.10.3.3 Tool Manufacturing Costs

11.10.3.4 Dies

FIGURE 11.23 Relationship between cutting time and material thickness for wire EDM processing (• carbide; ♦, tool steel). (Adapted from Fumo, A., Early Cost Estimating for Sintered Powder Metal Components, M.S. Thesis, Department of Industrial and Manufacturing Engineering, University of Rhode Island, Kingston, 1988.)

EXAMPLE

11.10.3.5 Punches

EXAMPLE

EXAMPLE

EXAMPLE

11.10.3.6 Core Rods

EXAMPLE

11.10.3.7 Total Tool Manufacturing Costs

11.10.4 Tool Accessory Costs

EXAMPLE

11.10.5 Tool Replacement Costs

EXAMPLE

11.10.6 Validation of the Tool Cost-Estimating Procedure

FIGURE 11.24 Comparison of tooling cost estimates with industry values for a range of powder metal parts.

FIGURE 11.25 Comparison of tooling cost estimates with industry values for a larger range of powder metal parts.

11.10.7 Sintering Costs

11.10.7.1 Continuous-Flow Furnaces

EXAMPLE

11.10.7.2 Batch Furnaces

FIGURE 11.26 Approximate heating and cooling cycle for batch-sintering furnaces.

11.10.8 Repressing, Coining, and Sizing

11.11 Modifications for Infiltrated Materials

11.11.1 Material Costs

11.11.2 Compaction Costs

11.11.3 Sintering Costs

11.12 Impregnation, Heat Treatment, Tumbling, Steam Treatment, and Other Surface Treatments

11.12.1 Processing Costs

TABLE 11.14 Typical Costs for Secondary Processes

11.12.2 Additional Material Costs

11.12.2.1 Self-Lubricating Bearing Materials

11.12.2.2 Materials Impregnated with Oil or Polymer

11.13 Some Design Guidelines for Powder Metal Parts

FIGURE 11.27 Design recommendations for minimum level widths. (Adapted from MPIF, Powder Metallurgy Design Manual, 3rd ed., Metal Powder Industries Federation, Princeton, NJ, 2007.)

FIGURE 11.28 Design modifications to reduce weak punch sections. (Adapted from MPIF, Powder Metallurgy Design Manual, 3rd ed., Metal Powder Industries Federation, Princeton, NJ, 2007.)

FIGURE 11.29 Design modifications to eliminate small punch sections. (Adapted from MPIF, Powder Metallurgy Design Manual, 3rd ed., Metal Powder Industries Federation, Princeton, NJ, 2007.)

11.14 Powder Injection Molding

FIGURE 11.30 Steps in the powder injection-molding process.

11.14.1 Feedstock Preparation and Pelletization

11.14.2 Molding

TABLE 11.15 Injection Molding Parameters for PIM and Plastics Molding

11.14.3 Debinding

11.14.4 Sintering

11.14.5 Secondary Operations

11.14.6 Feedstock Characteristics

TABLE 11.16 Some Materials Used for the Powder Injection Molding Process

TABLE 11.17 Some Materials Used in PIM Binder Systems

TABLE 11.18 Sample Binder Compositions for PIM

TABLE 11.19 Processing Parameters for Sample Binder Compositions

FIGURE 11.31 Density of the feedstock as the powder loading is increased. (Adapted from German, R.M., Powder Injection Molding, Powder Industries Federation, Princeton, NJ, 1990.)

EXAMPLE

11.14.7 Material Costs

EXAMPLE

11.14.8 Mold Cavity Geometry

11.14.9 Molding Costs

EXAMPLE

FIGURE 11.32 Two-level iron part produced by powder compaction and sintering.

References

12 Design for Sand Casting

12.1 Introduction

FIGURE 12.1 Assembled cope and drag mold.

12.2 Sand Casting Alloys

TABLE 12.1 Commonly Used Sand Casting Alloys

12.3 Basic Characteristics and Mold Preparation

12.3.1 Sand Preparation

12.3.2 Gating System

FIGURE 12.2 Typical gating system.

12.3.3 Mold Risers and Chills

12.3.4 Pattern Types

FIGURE 12.3 (a) Match-plate pattern; (b) separate cope and drag pattern plates.

12.3.5 Sand Compaction Methods

12.4 Sand Cores

12.5 Melting and Pouring of Metal

12.6 Cleaning of Castings

12.7 Cost Estimating

12.7.1 Metal Cost

TABLE 12.2 Furnace Cost Data for Sand Casting Alloys

12.7.2 Sand Costs

12.7.3 Tooling Costs

TABLE 12.3 Tool Life and Relative Costs

12.7.4 Processing Costs

12.8 Design Rules for Sand Castings

12.8.1 Avoid Sharp Angles and Multiple-Section Joints

FIGURE 12.4 (a) Constant casting thickness with uniform cooling; (b) effects of nonuniform cooling caused by abrupt section changes.

FIGURE 12.5 Examples of good and bad section configurations. (Adapted from Customers Foundry Orientation Manual, Robinson Foundry, Alexander City, AL, 1989.)

12.8.2 Design Sections of Uniform Thickness

TABLE 12.4 Minimal Economical Section Thicknesses for Different Section Lengths, SL

12.8.3 Proportion Inner Wall Thickness

12.8.4 Consider Metal Shrinkage in the Design

TABLE 12.5 Shrinkage Allowances of Casting Alloys

12.8.5 Use a Simple Parting Line

12.8.6 Define Appropriate Machining Allowances

12.8.7 Use Economical Tolerances

FIGURE 12.6 Appropriate tolerances for a cored casting.

12.9 Example Calculations

FIGURE 12.7 (a) Pump body casting; (b) casting core.

CASTING MATERIAL COST CALCULATIONS

MOLD AND CORE SAND COSTS

CORE AND MOLD MANUFACTURING COSTS

CLEANING COSTS

PIECE-PART COST

PATTERN AND CORE BOX COSTS

FIGURE 12.8 Idler Arm construction machine component.

FIGURE 12.9 Machine Bracket.

FIGURE 12.10 Two cavity layout, showing finished castings with cores in position.

References

13 Design for Investment Casting

13.1 Introduction

13.2 Process Overview

FIGURE 13.1 Simplified ceramic shell mold investment-casting process.

13.3 Pattern Materials

13.4 Pattern Injection Machines

FIGURE 13.2 Simple investment-casting pattern injection equipment.

FIGURE 13.3 Hydraulic pattern injection machine.

13.5 Pattern Molds

13.6 Pattern and Cluster Assembly

13.7 Ceramic Shell Mold

13.8 Ceramic Cores

13.9 Pattern Meltout

13.10 Pattern Burnout and Mold Firing

13.11 Knockout and Cleaning

13.12 Cutoff and Finishing

13.13 Pattern and Core Material Cost

TABLE 13.1 Pattern Material Properties

TABLE 13.2 Pattern Material Applications

TABLE 13.3 Core Material Properties

TABLE 13.4 Core Material Applications

TABLE 13.5 Volume Allowances for Solid Contraction of Metals

EXAMPLE

FIGURE 13.4 Sample part (dimensions in mm).

13.14 Wax Pattern Injection Cost

TABLE 13.6 Wax Injection Machine Data

EXAMPLE

13.15 Fill Time

EXAMPLE

13.16 Cooling Time

FIGURE 13.5 Cooling sections.

EXAMPLE

13.17 Ejection and Reset Time

EXAMPLE

EXAMPLE

13.18 Process Cost per Pattern or Core

TABLE 13.7 Wax Injection Machine Rates

TABLE 13.8 High-Pressure Ceramic Core Injection Machine Rates

EXAMPLE

13.19 Estimating Core Injection Cost

13.20 Pattern and Core Mold Cost

EXAMPLE

EXAMPLE

EXAMPLE

EXAMPLE

13.21 Core Mold Cost

13.22 Pattern and Cluster Assembly Cost

EXAMPLE

13.23 Number of Parts per Cluster

EXAMPLE

13.24 Pattern Piece Cost

EXAMPLE

13.25 Cleaning and Etching

13.26 Shell Mold Material Cost

EXAMPLE

13.27 Investing the Pattern Cluster

13.28 Pattern Meltout

13.29 Burnout, Sinter, and Preheat

13.30 Total Shell Mold Cost

EXAMPLE

13.31 Cost for Melting Metal

TABLE 13.9 Approximate Efficiency of Induction Melting for Various Materials

TABLE 13.10 Minimum Energy Required to Melt Alloys

EXAMPLE

EXAMPLE

TABLE 13.11 Machine Rates for Induction Furnaces

EXAMPLE

TABLE 13.12 Operator Rates for Induction Furnaces

13.32 Raw Base Metal Cost

13.33 Ready-to-Pour liquid Metal Cost

EXAMPLE

13.34 Pouring Cost

13.35 Final Material Cost

EXAMPLE

13.36 Breakout

EXAMPLE

13.37 Cleaning

13.38 Cutoff

EXAMPLE

13.39 Design Guidelines

References

14 Design for Hot Forging

14.1 Introduction

14.2 Characteristics of the Forging Process

FIGURE 14.1 Forging requiring a cranked parting line.

14.2.1 Types of Forging Processes

14.3 Role of Flash in Forging

FIGURE 14.2 (a) Forging of a simple axisymmetric part, (b) Load variation during the stroke for forging the part. (Adapted from Kalpakjian, S. and Schmid, S. Manufacturing Processes for Engineering Materials, 5th Ed., Prentice-Hall, Englewood Cliffs, NJ, 2007.)

14.3.1 Determination of the Flash Land Geometry

FIGURE 14.3 Flash land and flash gutter configuration.

TABLE 14.1 Selected Empirical Formulas for Flash Land Geometry

EXAMPLE

FIGURE 14.4 Steel forging for sample calculations.

14.3.2 Amount of Flash

TABLE 14.2 Flash Weight per Unit Length of Flash Line for Steel Forgings

EXAMPLE

14.3.3 Webs in Forgings

FIGURE 14.5 Web thickness related to projected area. (Adapted from Thomas, A. Die Design, Drop Forging Research Association, Sheffield, UK, 1980.)

14.4 Forging Allowances

FIGURE 14.6 Forging allowances for finish machining and draft.

FIGURE 14.7 Finish machining allowances for different materials. (Adapted from Jensen, J.E. Forging Industry Handbook, FIA, Cleveland, 1970.)

TABLE 14.3 Draft Allowances for Forgings

TABLE 14.4 Typical Minimum Edge and Fillet Radii for Rib/Web Type Forgings

14.5 Preforming during Forging

FIGURE 14.8 Typical forging sequence for a connecting rod. (Adapted from. Kalpakjian, S. and Schmid, S. Manufacturing Processes for Engineering Materials, 5th Ed., Prentice-Hall, Englewood Cliffs, NJ, 2007.)

FIGURE 14.9 Typical blocker cross-sections compared to the finish forging cross-sections. (a) General design procedure, (b) Sample cross-sections. (Adapted from Biswas, S.K. and Knight, W.A. International Journal of Production Research, 14, pp. 23–49, 1976.)

FIGURE 14.10 Forging sequence design for a connecting rod. (a) Mass distribution stages, (b) Blocker cross-sections. (Adapted from Biswas, S.K. and Knight, W.A. International Journal of Production Research, 14, pp. 23–49, 1976.)

14.5.1 Die Layout

FIGURE 14.11 Typical multi-impression hammer forging dies. (Adapted from American Society of Metals, Metals Handbook: Metalworking-Bulk Forming, Vol. 14, Part A, ASM, Cleveland, 2005.)

FIGURE 14.12 Die layout for hammer forging die. (Adapted from Biswas, S.K. and Knight, W.A. International Journal of Production Research, 14, pp. 23–49, 1976.)

FIGURE 14.13 Typical die lock configuration. (Adapted from Thomas, A. Die Design, Drop Forging Research Association, Sheffield, UK, 1980.)

14.6 Flash Removal

14.7 Classification of Forgings

FIGURE 14.14 Forging classification, allocation of first digit.

FIGURE 14.15 Allocation of second digit for compact and flat parts.

FIGURE 14.16 Allocation of second digit for long parts.

EXAMPLE

14.7.1 Forging Complexity

14.7.1.1 Shape Complexity Factor

14.7.1.2 Number of Surface Patches in the Part

14.8 Forging Equipment

14.8.1 Gravity Drop Hammers

FIGURE 14.17 Schematic of various types of drop hammer: (a) Board hammer, (b) Belt hammer, (c) Chain hammer, (d) Airlift hammer. (Adapted from Kalpakjian, S. and Schmid, S. Manufacturing Processes for Engineering Materials, 5th Ed., Prentice-Hall, Englewood Cliffs, NJ, 2007.)

14.8.2 Double Acting or Power Hammers

14.8.3 Vertical Counterblow Hammers

14.8.4 Horizontal Counterblow Hammers

14.8.5 Mechanical Presses

FIGURE 14.18 Schematic of various types of forging press mechanisms: (a) Crank press, (b) Knuckle joint press, (c) Friction screw press, (d) Hydraulic press. (Adapted from Kalpakjian, S. and Schmid, S. Manufacturing Processes for Engineering Materials, 5th Ed., Prentice-Hall, Englewood Cliffs, NJ, 2007.)

14.8.6 Screw Presses

14.8.7 Hydraulic Presses

14.8.8 Choice of Forging Machine Type

14.8.9 Comparisons of Forging equipment

TABLE 14.5 Some Comparative Data for Forging Equipment

TABLE 14.6 Equivalent Capacities of Presses and Hammers

FIGURE 14.19 Average usable blow rates for forging equipment. (Adapted from Knight, W.A. International Journal of Advanced Manufacturing Technology, 7, pp. 159–167, 1992.)

FIGURE 14.20 Operating cost per operation relative to 1000-lb power hammer. (Adapted from Leone, J.L. Relative Forging Costs Analysis and Estimation, MS Thesis, University of Massachusetts, Amherst, 1983.)

FIGURE 14.21 Relative operating cost per operation for forging equipment. (Adapted from Knight, W.A. and Poli, C.R. Machine Design, January 24, pp. 94–99, 1985.)

14.9 Classification of Materials

TABLE 14.7 Classification of Forging Materials

14.10 Forging Costs

FIGURE 14.22 Breakdown of average costs for hot forging. (Adapted from Hobdell, A.C. and Thomas, A. Approaches to cheaper forgings, Metal Forming, 36(1), p. 17, 1969.)

14.10.1 Material Costs

EXAMPLE

14.10.2 Equipment Operating Costs

FIGURE 14.23 Data for compact forgings, Shape Class 0.

FIGURE 14.24 Data for flat forgings, Shape Class 1.

FIGURE 14.25 Data for long straight forgings, Shape Class 2.

FIGURE 14.26 Data for long bent forgings, Shape Class 3.

14.10.3 Examples of equipment Selection

FIGURE 14.27 Comparison between predicted and actual forging equipment capacities for flat, round forgings (Adapted from Knight, W.A. International Journal of Advanced Manufacturing Technology, 7, pp. 159–167, 1992.)

FIGURE 14.28 Comparison between predicted and actual forging equipment capacities for flat, nonround forging. (Forgings F and M. are precision forgings in aluminum alloy.) (Adapted from Knight, W.A. International Journal of Advanced Manufacturing Technology, 7, pp. 159–167, 1992.)

FIGURE 14.29 Comparison between predicted and actual forging equipment capacities for long forging. (Adapted from Knight, W.A. International Journal of Advanced Manufacturing Technology, 7, pp. 159–167, 1992.)

14.10.4 Forging Processing Costs

EXAMPLE

14.10.5 Forging Machine Setup Costs

EXAMPLE

14.11 Forging Die Costs

14.11.1 Initial Die Costs

14.11.2 Estimation of Costs for Multi-impression Forging Dies

14.11.2.1 Die Material Costs

EXAMPLE

14.11.2.2 Multi-Impression Die Manufacturing Costs

EXAMPLE

EXAMPLE

EXAMPLE

EXAMPLE

EXAMPLE

EXAMPLE

EXAMPLE

EXAMPLE

EXAMPLE

14.12 Die life and Tool Replacement Costs

EXAMPLE

14.13 Costs of Flash Removal

14.13.1 Flash removal Processing Costs

EXAMPLE

14.13.2 Tooling Costs for Flash removal

EXAMPLE

TABLE 14.8 Data for Estimating Trim Die-Manufacturing Times

EXAMPLE

14.14 Other Forging Costs

14.14.1 Billet Preparation

14.14.2 Billet Heating Costs

FIGURE 14.30 Sample forging A.

FIGURE 14.31 Sample forging B.

FIGURE 14.32 Sample forging C.

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