Design for Manufacture and Assembly

1. Design for Manufacture and Assembly ME 475/476 Some slides in this presentation have been provided courtesy of Emeritus Professor, Dr. Perry Carter, School of Technology at Brigham Young University

2. Schedule

3. Assignments

4. What Would you Like to Learn About Design for Manufacture & Assembly (DFM/DFA)?

5. Important Considerations in Product Design • Functionality • Safety • Appearance • Weight • Maintainability • Recyclability • Reliability • Manufacturability • ….

6. What is the Cost of a Product?

7. Reduced Production Costs

8. Four Activities of Manufacturing • Changing the shape of materials • Changing the properties of materials • Assembling materials (as component parts) • Creating or organizing the tools, machines and systems to make the first three mf’g. activities happen

9. We can Make Anything, Right?

10. Engineering isa PeopleProfession

11. “Nowhere in a company is the need for coordination more acute than between the people who are responsible for product design and those responsible for manufacturing.” Harvard Business Review

13. A Very Helpful Book

14. The Cost of Design Changes… Time of Change Relative Cost $1 $10 $100 $1,000 $10,000 • During Concept selection and early stages of product & process design • During design testing • During process testing • During test production • During final production

15. Improving Manufacturability • The single most important principle to improving manufacturability is to want to • The second most significant principle to improving manufacturability is to do it in the early stages of design • A third important principle is to seek to learn from others • A significant additional guideline for improving manufacturability is to strive for Simplicity! • Reduce the number of parts • Reduce tolerances • Use standard parts whenever possible • Reduce number of fasteners & adjustments

16. Manufacturability (Cont’d) • Seek to learn about the capabilities and limitations of manufacturing processes, equipment, and materialsbeforeyou design the product. • Consider preferred vs. nonpreferredprocesses and materials • Consider manufacturing cost targets for the different parts of the your product

17. What is DFMA? DFMA (Design for Manufacturability and Assembly) is a structured method for comparingalternative product designs with respect to manufacturability These comparisons are usually based on cost or time…

18. What are the benefits of DFMA? • Improved communication and decision making • Earlier and fewer design changes • Improved Quality • Reduced production costs • Shorter time to market • Increased market share and profits…

19. One Example…

20. Three principle parts of the Porsche manifold Two A’s and one B make up one C

21. Designing for the Process

22. Mf’g. Processes Reference Guide • Breaks 125 mfg. processes into three categories: • - Knowledge • - Application • Development • Defines, explains each process • Encourages integration of design and manufacturing to yield better designed products

23. What Mfg. Process Should I Use?

24. Tight Tolerances Cost Money! Ken Forester has prepared a nice handout to get you started…

25. Designing for the Process: Example Ford Air filter cover, initial release

26. Designing for the Process

27. Designing for the Process Ford air filter cover after redesign

28. Design for Assembly • What does DFA accomplish? • What are the basic assembly tasks? • What are the cost drivers associated with these assembly tasks? - Reduce cost!

29. What are basic assembly tasks? • Handling • Grasping, separating from bulk, orienting… • Insertion • Aligning, engaging, inspection • Fastening • Clamping, threading, plastic deformation, adhesive, etc.

30. Some Tips… • Design so the Assembly Process can be completed in a layered fashion – preferably from above • Consider easy part handling • Design mating parts that are easy to insert and align • Avoid part designs that will cause tangling with identical parts • Make parts symmetrical to aid in automatic orientation • If symmetry can’t be achieved, exaggerate the asymmetrical features…

31. Part Handling Effect of Part Size on Handling Time

32. Part Tangling

33. Spring Tangling

34. Insertion Effect of Chamfers

35. Insertion

36. Example of Obstructed Access

37. Alignment

38. Assembly Time Example

39. 3. Fasteners

40. Fastener Costs… • Number; type • High assembly time • Quality may be poor • Higher quality is expensive • Prone to assembly errors • Cost of inventory

41. Other Methods of Fastening

42. What is the Cost of Inventory? • Documentation • Inventory space • Inventory cost of h’wd. • Shipping • Incoming inspection • Vendor relations • Vendor qualification • Part certification • Failure replacement Lucent Technologies reports it costs$15,000/year to maintain one electronic part certification and $150,000 for a new part

43. Product Reliability Improvement Product reliability, that is mean time between failures (MTBF), is inversely tied to part count!

44. Proof-of Concept vs. Prototype

45. Watch for Over-Constraint in Design

46. Avoid Adjustments…

47. What constitutes a theoretically necessary part? Identify parts that don’t meet theoretical criteria for being separate parts…and eliminate them if possible • Motion • Material • Access

48. Motion 1.  During the normal operation of the product, does this part moverelative to all the other parts already assembled?

49. Material 2.   Must this part be of a different material than all the other parts already assembled? (Reasons should be based on fundamental, properties of the material such as electrical conductivity, thermal conductivity, vibration damping, hardness, modulus, etc.)

50. Access 3.   Must this part be separate from all other assembled parts to allow the assembly of other theoretically necessary parts. This could involve parts that must pass through an opening requiring a door, cover, lid etc. that must be removable to allow assembly of other internal parts.