1. Integrating Product and Process Engineering Activities
Dr. Richard A. Wysk
Leonhard Chair in Engineering
The Pennsylvania State University
University Park, PA 16802

2. PRODUCTION ENGINEERING
Specification
Raw Materials
Parts
Assemblies
Function,
Cost, weight
User, etc.
PLANNING
CONTROL
DESIGN
Manufacturability
Performance
Capabilities
PRODUCT ENGINEERING
PROCESS ENGINEERING
PRODUCTION ENGINEERING

3. A Vision of Integrated Engineering Systems (cont.)
INTEGRATION ENGINEERING
tools and techniques that can be used to assist in combining planning, design, construction and management of a product.

4. Product, Process and Production Models
Product Engineering
Library of features
Feature interactions
Process Engineering
Process / Feature links
Inter-feature linkages
Inter-process linkages
Production Engineering
System Specifics
Machine Specifics
Fixture Specifics
Tool Specifics

5. A Simple IPPD Illustration

6. Integrating Design and Manufacturing
Process Tolerance Chart -- limiting conditions
Process
Dimensional Accuracy
Positional Accuracy
Drill (twist) +
.008
.005
Reaming
.0025
Bore (semi-finish)
.0035
Bore (Finish)
.002

7. Generative Process Planning
Find the most efficient process capable
of obtaining the design specification.
Order the plans in an efficient manner.
Get parameters from a handbook.
Modify as required.

8. A Traditional Process Plan
Table 2
Process Plan #1 for Case Study Bracket
Operation
Description
Tooling V
(ft/min) F
(in) d
Time
(min) 10
load part into fixture .5 20
Drill large hole
.750
300
.010
.21 30
Drill small hole (8)
.500
250
.008
1.70 40
Unload and visually
inspect
1.00
Total time min t m = fv Dl 12 p
<large hole> = . 60 *
010
650
750
= .21min = 12.75sec
<small hole> =
008 50 5
= .2125min = 11.75sec each

9. Process Tolerance Chart is really a Statistically-based Entity
Process Tolerance Chart -- limiting conditions
Process
Dimensional Accuracy ( + 3 s )
Positional Accuracy
Drill (twist)
.008
.005
Reaming
.0025
Bore (semi-finish)
.0035
Bore (Finish)
.002

10. Can we make some statistical inferences? (Size first)
The likelihood that each hole size dimension is good is + 3 s (from Process tolerance chart). If all holes are normally distributed and independent, then
P{>1 Bad hole dimension} = 1 - [P(good hole dimension)]no. of holes
P{>1 Bad hole dimension} = = = 2.4%

11. How about location? All locations were specified RFS.
What does this mean?
Location requirements are independent of feature size

12. The likelihood of having a location out of spec becomes
For RFS Features
The likelihood of having a location out of spec becomes
P[x < ] + P[x> ] =
P P
= P[z < -4.82] + P[z > +4.82]
= 2*[1 - F(4.82)]
=2*[ ] =

13. For all 9 holes
P{Bad location} = 1 - ( )9
= = .0004

14. The Expected Part Cost Cp = cost to produce + warranty cost
= $ P{defect} Cost of defect
Assuming that the dimensional and location probabilities are independent we get
P{good part} = [P{good dimension L good location}]no. of holes
P{defective part} = 1 - P{good part}
= 1 - [P{good dimension L good location}] no. of holes
= 1 - [ * ( )]9
= .0244, and
Cp = $ ($50) = $2.92 per part

15. Does the Process planning process end here? An Alternative Process Plan
Table 3
Process Plan #2 for Case Study Bracket
Operation
Description
Tooling V f d
Time (min) 10
Load part into fixture
47/64
0.5 20
Drill large hole
.750
.010
1.70 30
Ream large hole
31/64
300
.008
0.21 40
Drill small holes (8)
.500 50
Ream small holes (8)
250
Unload and visually inspect
1.00
Total time min

16. From the Process Tolerance Chart
Process Tolerance Chart -- limiting conditions
Process
Dimensional Accuracy ( + 3 s )
Positional Accuracy
Drill (twist)
.008
.005
Reaming
.0025
Bore (semi-finish)
.0035
Bore (Finish)
.002
Choose either Reaming or boring to improve the quality of the product. Since reaming is a more efficient process, we will first look at it.

17. Calculating the percent defective=

18. Computing the likelihood of a bad part

19. What can we say about tradition Process planning procedures?
They do not take defects into account (based on costs).
Alternatives should be considered.
Procedure is easy to implement.

20. What if Position was specified as Maximum Material Condition?

21. What if the holes were specified as MMC?
Size dimension will be the same.
How about position?
Position is not independent of size.

22. Why is MMC important? Dm Interchangeable fit and
assembly is based on it. Dm
LMC

23. Calculating Positional Defects
It should be obvious that this value will be less than the RFS case.

24. Calculating proportion defective due to location

25. Proportion defective and cost

26. Is this the best plan? Still don’t know
What about secondary processing activities?
Cost [additional processes] < Cost [warranty problems/piece]

27. SUMMARY AND CONCLUSIONS
Design for manufacturing is not well understood
In many cases, the devil is in the detail.
Statistical information is becoming more available and should be used as part of the design and planning process.