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?
Bulb Boss Costs
Cost Remaining:
Selling Price:
$5.00
Retail Store Gross Profit:
$2.50
Distribution:
$0.75
$1.75
Overhead of Manufacturing:
$0.50
$1.25
Development Cost:
$0.10
$1.15
Warrantee Cost:
$0.05
$1.10
Advertising:
$0.40
$0.70
Packaging:
$0.20
Assembly:
Materials:
$0.35
Manufacturing Profit:
$0.00

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 is a People Profession

11. Harvard Business Review
“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

12. Clint Eastwood

13. A Very Helpful Book

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

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 materials before you design the product.
Consider preferred vs. nonpreferred processes and materials
Consider manufacturing cost targets for the different parts of the your product

17. The Importance of Seeing Things in New Ways:
"I had an immense advantage over many others dealing with the problem inasmuch as I had no fixed ideas derived from long-established practice to control and bias my mind, and did not suffer from the general belief that whatever is, is right." - Sir Henry Bessemer inventor of the modern Bessemer Steel making Process

18. What is DFMA?
DFMA (Design for Manufacturability and Assembly) is a structured method for comparing alternative product designs with respect to manufacturability
Back in the 70’s there were no DFM classes in engineering. Now every program has one. Why is that?
These comparisons are usually based on cost or time…

19. 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…

20. One Example…
Plastic intake manifold from Porsche SUV. Following the success of the GM experiment.

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

22. Designing for the Process

23. 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

24. What Mfg. Process Should I Use?
Preferred Methods
Nonpreferred Methods
Castings or plastic
Completely Machined
Near net-shaped casting
Casting
Screw Machine
Lathe Turning
Milling
Jig bore
Turning
Standard Materials
Nonstandard Materials
Tolerances > +/
Tolerance < +/
6061 Aluminum
Steels, stainless steels
303 Stainless Steel
Other types of stainless steels
Thermoplastics
Thermosets
Hardness < or = 41 Rc
Harness > 41 Rc

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

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

27. Designing for the Process

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

29. 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!

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

31. 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…

32. Effect of Part Size on Handling Time
Part Handling
Effect of Part Size on Handling Time

33. Part Tangling

34. Spring Tangling

35. Insertion
Effect of Chamfers

36. Insertion

37. Example of Obstructed Access

38. Alignment

39. Assembly Time Example

40. 3. Fasteners

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

42. Other Methods of Fastening

43. 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

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

45. Proof-of Concept vs. Prototype

46. Watch for Over-Constraint in Design

47. Avoid Adjustments…

48. 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

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

50. 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.)

51. 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.

52. DFMA Examples Flowserve valve GM Intake Manifold Jeep Throttle Linkage
XEROX door lock
Automotive “A-arm”
Coat Rack

53. Standardized Parts…
Interchangeable flanges

54. What Material Should I choose?

55. Manifold Cost Comparison
Aluminum design:
Sand casting process $3.53
Machining $1.70
Assembly _____
Total processing $5.23
Nylon design:
Injection Molding $2.66
Assembly _____

56. Redesign Benefits 45% unit cost savings 66% weight savings
Simplified assembly & service
Improved emissions performance due to EGR mounting
Improved engine performance due to reduced intake air temperature
Reduced shipping costs due to weight reduction
Increased part standardization

57. British Motors Example

58. Avoid Unnecessary Part Numbers

59. Modern one-piece A- arm

61. 1964 Jeep Throttle Pedal 38 parts 23 fasteners
228 seconds assembly time
1 theoretically required part
1.3% assembly efficiency

62. XEROX Door Lock

63. XEROX Door Lock Original Design Redesign 62 parts
Total time = 6.9 min.
Assembly cost = $2.76
Parts cost = $9.80
Min No. parts = 10
Efficiency = 4.8%
Redesign
17 parts
Total time = 1.48 min.
Assembly cost = $0.59
Parts cost = $7.44
Min No. parts = 10
Efficiency = 22.5%

64. Coat Rack Design for assembly analysis by MFG 572 student team
16 parts, including 9 fasteners

65. One single part requiring several forming operations and one weld.

66. Summary
Observe what others have done, good and bad, in the way things are made
Avoid the “us vs. them” paradigm
Seek input from experts, be eager to learn
Design your parts considering the mf’g. process
If you can, reduce the number of parts
Seek to eliminate fasteners and adjustments
Keep in mind that it’s the obvious that is most often overlooked in DFMA
Most importantly—consider manufacturability early in the design process…

67. Thank You!