1. PART DESIGN SPECIFICATION
Dr. R. A. Wysk 1

2. Agenda Go over engineering specifications Functional requirements
Form, fit and function
Dimensioning
Tolerancing
Engineering drawings
datum 2

3. Materials
Read Chapter 2 and 3 from Computer Aided manufacturing (3rd Edition)
Overview of engineering design
Mechanical design representations
Engineering drawing
Geometric dimensioning and tolerancing
AMSE Y14.5 3

4. THE DESIGN PROCESS Product Engineering
Off-road bicycle that ...
1. Conceptualization
2. Synthesis
3. Analysis
4. Evaluation
5. Representation
Design Process
How can this be accomplished?
1. Clarification of the task
2. Conceptual design
3. Embodiment design
4. Detailed design
Functional requirement -> Design
Steps 1 & 2 Select material and properties, begin geometric
modeling (needs creativity, sketch is sufficient)
mathematical, engineering analysis
simulation, cost, physical model
formal drawing or modeling 4

5. DESIGN REPRESENTATION
Engineering
Representation
Manufac-
turing
• Verbal
• Sketch
• Multi-view orthographic drawing (drafting)
• CAD drafting
• CAD 3D & surface model
• Solid model
• Feature based design
Requirement of the representation method
• precisely convey the design concept
• easy to use 5

6. A FREE-HAND SKETCH Orthographic Projection6

7. A FORMAL 3-VIEW DRAWING 7 0.9444" A 4 holes 1/4" dia
around 2" dia , first
hole at 45° 
2.000
0.001 A 7

8. DESIGN DRAFTING Third angle projection Drafting in the third angle Y Pz o n t a l Z I X I I V F r o n t a l p l a n e
Third angle projection
Drafting in the third angle 8

9. INTERPRETING A DRAWING9

10. DESIGN DRAFTING Partial view Cut off view and auxiliary view2 .  1
Partial view A - A
Cut off view and auxiliary view
Provide more local details 10

11. DIMENSIONING Requirements 1. Unambiguous 2. Completeness
3. No redundancy
Incomplete
dimensioning
0.98 '
1.22 '
1.72 '
0.83 '
3.03 '
Redundant dimensioning
0.86 '
1.22 '
0.83 '
3.03 '
Adequate dimensioning 11

12. TOLERANCE Dimensional tolerance - conventional
Geometric tolerance - modern
nominal dimension + -
means a range
tolerance
+ 0.10
- 0.00
+ 0.00
- 0.10
unilateral
bilateral
0.95
1.05 + - 12

13. TOLERANCE STACKING
1. Check that the tolerance & dimension specifications are
reasonable - for assembly.
2. Check there is no over or under specification.
"TOLERANCE IS ALWAYS ADDITIVE" why?
1.20 '
±0.01
0.80 '
±0.01
1.00 '
±0.01 ?
What is the expected dimension and tolerances?
d = = 3.00
t = ± ( ) = ± 0.03 13

14. TOLERANCE STACKING (ii)?
0.80 '
±0.01
1.20 '
±0.01
3.00 '
±0.01
What is the expected dimension and tolerances?
d = = 1.00
t = ± ( ) = ± 0.03 14

15. TOLERANCE STACKING (iii)x
1.20 '
±0.01 ?
0.80 '
±0.01
3.00 '
±0.01
Maximum x length = = 1.03
Minimum x length = = 0.97
Therefore x = ± 0.03 15

16. TOLERANCE GRAPH A B C D E G(N,d,t)
N: a set of reference lines, sequenced nodes
d: a set of dimensions, arcs
t: a set of tolerances, arcs
d : dimension between references i & j
t : tolerance between references i & j ij ij
Reference i is in front of reference j in the sequence. 16

17. EXAMPLE TOLERANCE GRAPH
d,t
d,t
d,t
A B C D E
d,t
different properties
between d & t 17

18. OVER SPECIFICATION
If one or more cycles can be detected in the graph, we say that the dimension and tolerance are over specified. d1 d2
A B C
d1,t1
d2,t2 d3
Redundant dimension
d3,t3 A B C t1 t2
A B C t3
Over constraining tolerance
(impossible to satisfy) why? 18

19. UNDER SPECIFICATION
When one or more nodes are disconnected from the graph, the
dimension or tolerance is under specified. d1 d2
A B C D E d3 A B C D E
C D
is disconnected from the
rest of the graph.
No way to find 19

20. PROPERLY TOLERANCED A B C D E
d,t
d,t
d,t
A B C D E
d,t 20

21. TOLERANCE ANALYSIS For two or three dimensional tolerance analysis:
i. Only dimensional tolerance
Do one dimension at a time.
Decompose into X,Y,Z, three one dimensional problems.
ii. with geometric tolerance
? Don't have a good solution yet. Use simulation? d i a m e t e r
& t o l e r a n c e
A circular tolerance zone, the size is influenced
by the diameter of the hole. The shape of the
hole is also defined by a geometric tolerance. t r u e p o s i t i o n 21

22. 3-D GEOMETRIC TOLERANCE PROBLEMS
datum surface
datum
surface
± t
Reference
frame
perpendicularity 22

23. TOLERANCE ASSIGNMENT Tolerance is money
• Specify as large a tolerance as possible as long as functional and assembly requirements can be satisfied.
(ref. Tuguchi, ElSayed, Hsiang, Quality Engineering in Production Systems, McGraw Hill, 1989.) Q u a l i t y
function C o s t
cost + t - t d ( n o m i n a l d i m e n s i o n )
Tolerance value
Quality cost 23

24. REASON OF HAVING TOLERANCE
• No manufacturing process is perfect.
• Nominal dimension (the "d" value) can not be achieved exactly.
• Without tolerance we lose the control and as a consequence cause functional or assembly failure. 24

25. EFFECTS OF TOLERANCE (I)
1. Functional constraints
e.g.
flow rate
d ± t
Diameter of the tube affects the flow. What is the allowed
flow rate variation (tolerance)? 25

26. EFFECTS OF TOLERANCE (II)
2. Assembly constraints
e.g. peg-in-a-hole dp
How to maintain the clearance? dh
Compound fitting
The dimension of each segment affects others. 26

27. RELATION BETWEEN PRODUCT & PROCESS TOLERANCES
Machine uses the locators as the reference. The distances from the machine coordinate system to the locators are known.
The machining tolerance is measured from the locators.
• In order to achieve the tolerances, the process tolerance must be or better.
• When multiple setups are used, the setup error need to be taken into consideration. A . 1 t o l e r a n c e s
Design specifications S e t u p l o c a t o r s . 5 . 5 . 5
Process tolerance 27

28. TOLERANCE CHARTING
A method to allocate process tolerance and verify that the process sequence and machine selection can satisfy the design tolerance.
Not shown are
process tolerance
assignment and
balance
blue print
Operation
sequence
produced tolerances:
process tol of 10 + process tol of 12
process tol of 20 + process tol 22
process tol of 22 + setup tol 28

29. SURFACE FINISH w a v i n e s s r o u g h n e s s r o u g h n e s s w id t h w a v i n e s s w i d t h
Usually
simplified:
waviness height
waviness width 63
roughness
height
( inch) 63
0.010
0.005
roughness width cutoff
default is 0.03" (ANSI Y )
roughness width
Lay
(inch) 29

30. PROBLEMS WITH DIMENSIONAL TOLERANCE ALONE
As designed: 1 . . 1 6 . . 1
As manufactured: 1 . 1
Will you accept the part
at right?
Problem is the control of
straightness.
How to eliminate the
ambiguity? 1 . 1 1 . 1 6 . 30

31. GEOMETRIC TOLERANCES
ANSI Y14.5M-1977 GD&T (ISO 1101, geometric tolerancing;
ISO positional tolerancing; ISO 5459 datums;
and others), ASME Y
FORM
straightness
flatness
Circularity
cylindricity
ORIENTATION
perpendicularity
angularity
parallelism
Squareness
roundness
LOCATION
concentricity
true position
symmetry
RUNOUT
circular runout
total runout
PROFILE
profile
profile of a line 31

32. DATUM & FEATURE CONTROL FRAME
Datum: a reference plane, point, line, axis where usually a plane where you can base your measurement.
Symbol:
Even a hole pattern can be used as datum.
Feature: specific component portions of a part and may include one or more surfaces such as holes, faces, screw threads, profiles, or slots.
Feature Control Frame: A
datum
// M A
modifier
symbol
tolerance value 32

33. MODIFIERS Maximum material condition MMC assembly
Regardless of feature size RFS (implied unless specified)
Least material condition LMC less frequently used
Projected tolerance zone
Diametrical tolerance zone
T Tangent plane
F Free state
maintain critical wall thickness or critical location of features.
MMC, RFS, LMC
MMC, RFS
RFS 33

34. SOME TERMS MMC : Maximum Material Condition
Smallest hole or largest peg (more material left on the part)
LMC : Least Material Condition
Largest hole or smallest peg (less material left on the part)
Virtual condition:
Collective effect of all tolerances specified on a feature.
Datum target points:
Specify on the drawing exactly where the datum contact points should be located. Three for primary datum, two for secondary datum and one or tertiary datum. 34

35. DATUM REFERENCE FRAME .
Three perfect planes used to locate the imperfect part.
a. Three point contact on the primary plane
b. two point contact on the secondary plane
c. one point contact on the tertiary plane P r i m a r y T e r t i a r y S e c o n d a r y
Secondary
O M A B C
primary
Tertiary C B A 35

36. STRAIGHTNESS Tolerance zone between two straightness lines.. 1
Value must be smaller than the size tolerance.
1.000 '
±0.002 M e a s u r e d e r r o r Š . 1 . 1
1.000 '
±0.002 . 1
Design
Meaning 36

37. 37

38. FLATNESS Tolerance zone defined by two parallel planes. . 1 1.000 '. 1
1.000 '
±0.002 p a r a l l e l p l a n e s . 1 38

39. CIRCULARITY (ROUNDNESS)
a. Circle as a result of the intersection by any plane perpendicular to
a common axis.
b. On a sphere, any plane passes through a common center.
Tolerance zone bounded by two concentric circles. . 1
1.00 '
±0.05 . 1 T o l e r a n c e z o n e
At any section along the cylinder 39

40. CYLINDRICITY
Tolerance zone bounded by two concentric cylinders within which the cylinder must lie. . 1
1.00 '
±0.05
Rotate in a V . 1
Rotate between points 40

41. PERPENDICULARITY
A surface, median plane, or axis at a right angle to the datum plane
or axis. . 2 T A . 2 A . 2
1.000 '
±0.005 t o l e r a n c e z o n e p e r p e n d i c u l a r t o t h e d a t u m p l a n e
0.500 '
±0.005 A
2.000 '
±0.005 A . 2 d i a m e t e r t o l z o n e i s p e r p e n d i c u l a r O 1 . . 1 t o t h e d a t u m p l a n e . 2 A 41

42. ANGULARITY
A surface or axis at a specified angle (orther than 90°) from a datum
plane or axis. Can have more than one datum. . 5 A 1 . 5 . 5 4
3.500 '
±0.005 A 42

43. PARALLELISM
The condition of a surface equidistant at all points from a datum plane,
or an axis equidistant along its length to a datum axis. . 1 A
1.000 "
±0.005
2.000 "
±0.005 A . 1 43

44. PROFILE A uniform boundary along the true profile within whcih
the elements of the surface must lie. . 5 A B B A . 1 44

45. RUNOUT
A composite tolerance used to control the functional relationship
of one or more features of a part to a datum axis. Circular runout
controls the circular elements of a surface. As the part rotates
360° about the datum axis, the error must be within the tolerance
limit.
1.500 "
±0.005 A
0.361 "
±0.002 . 5 A D e v i a t i o n o n e a c h c i r c u l a r c h e c k r i n g i s l e s s t h a n t h e D a t u m t o l e r a n c e . a x i s 45

46. TOTAL RUNOUT 1.500 " ±0.005 A 0.361 " ±0.002 . 5 A D e v i a t i o n o. 5 A D e v i a t i o n o n t h e t o t a l s w e p t w h e n t h e p a r t i s r o t a t i n g D a t u m i s l e s s t h a n t h e a x i s t o l e r a n c e . 46

47. TRUE POSITION Dimensional tolerance Hole center tolerance zone. 2 2 1 . . 1 1 . 2 . 1 O . 8 . 2
Hole center tolerance zone O . 1 M A B
True position
tolerance T o l e r a n c e z o n e . 1 d i a 1 . B A 1 . 2 47

48. HOLE TOLERANCE ZONE Tolerance zone for dimensional toleranced
hole is not a circle. This causes some assembly
problems.
For a hole using true position tolerance
the tolerance zone is a circular zone. 48

49. TOLERANCE VALUE MODIFICATION1 . . 2 O . 1 M A B
Produced True Pos tol
hole size
out of diametric tolerance
out of diametric tolerance 1 .
M L S B 1 . 2
MMC
LMC A
The default modifier for
true position is MMC.
For M the allowable tolerance = specified tolerance + (produced hole
size - MMC hole size) 49

50. MMC HOLE ,
Given the same peg (MMC peg), when the produced hole size is greater than the MMC hole, the hole axis true position tolerance zone can be enlarged by the amount of difference between the produced hole size and the MMC hole size. 50

51. PROJECTED TOLERANCE ZONE
Applied for threaded holes or press fit holes to ensure interchangeability
between parts. The height of the projected tolerance zone is the thickness
of the mating part. . 3 7 5 - 1 6 U N C - 2 B O . 1 M A B C . 2 5 p 51

52. SOME NUMBERS
Krulikowski, A., GD&T Challenges the Fast Draw, MFG ENG, Feb 1994.
GD&T drawings are more expansive to make, however, saves revision cost.
Drawing revision costs $500 - $2000 on the paper work
How much does it cost to “put a part number” onto a part? Estimates range from $1,000 -$10,000. 52

53. Process Engineering
Dr. R. A. Wysk 53

54. PROCESS ENGINEERING
• Process planning is also called: manufacturing planning, process planning, material processing, process engineering, and machine routing.
• Which machining processes and parameters are to be used (as well as those machines capable of performing these processes) to convert (machine) a piece part from its initial form to a final form predetermined (usually by a design engineer) from an engineering drawing.
• The act of preparing detailed work instructions to produce a part.
• How to realize a given product design. 54

55. Operation programming
PRODUCT REALIZATION
Product design
Process planning
Operation programming
Verification
Scheduling
Execution
Process,
machine
knowledge
Scheduling
knowledge 55

56. PROCESS PLANNING Process Planning Design Machine Tool
Scheduling and Production Control 56

57. PROBLEMS FACING MANUFACTURING INDUSTRY
Only 11% of the machine tools in the U.S. are programmable.
More than 53% of the metal-working plants in the U.S. do not have even one computer-controlled machine.
Some problems:
Cannot justify the cost
Lack of expertise in using such machines
Too small a batch size to offset the planning and programming costs
Source: Kelley, M.R. and Brooks, H., The State of Computerized Automation in US Manufacturing, J.F. Kennedy School of Government, Harvard University, October 1988.
Potential benefits in reducing turnaround time by using programmable machine tools have not been realized due to time, complexity and costs of planning and programming. 57

58. One-of-a-kind and Small batch
DOMAIN
One-of-a-kind and Small batch
Objectives: Lead-time, Cost
Approaches: process selection, use
existing facilities.
Mass production
Objective: Cost
Approaches: process design, optimization,
materials selection, facilities
design 58

59. How do we process engineer?
How can we make it?
How much does it cost?
How long will it take us to complete it?
How reliable will it be?
How can we recycle it 59

60. How can we make it? Is this like something else that we’ve done?
Yes; What methods were used?
No; Design a new process 60

61. What methods were used? Machining methods Pressworking
Welding/fabrication
Casting
Powder materials
Layered deposition
Others 61

62. Welding/fabrication: Additive techniques+ + =
Final Product
Weld
Add-on
Weld
Add-on
Initial
Stock 62

63. Machining Methods: Subtractive techniques- = = -
Final Product
Initial
Stock
Drilling
Slotting 63

64. Casting: Form Methods = 64

65. ENGINEERING DESIGN MODELING
CSG MODEL
B-REP MODEL 65

66. INTERACTION OF PLANNING FUNCTIONS
SETUP PLANNING
GEOMETRIC REASONING
• feature relationship
• approach directions
• process constraints
• fixture constraints
• global & local geometry
PROCESS SELECTION
• process capability
• process cost
FIXTURE PLANNING
• fixture element function
• locating, supporting, and
clamping surfaces
• stability
CUTTER SELECTION
• available tools
• tool dimension and geometry
• geometric constraints
CUTTER PATH GENERATION
MACHINE TOOL SELECTION
• feature merging and split
• path optimization
• obstacle and interference
avoidance
• machine availability, cost
• machine capability 66

67. PROCESS PLAN
• Also called : operation sheet, route sheet, operation planning summary, or another similar name.
• The detailed plan contains:
route
processes
process parameters
machine and tool selections
fixtures
• How detail the plan is depends on the application.
• Operation: a process
• Operation Plan (Op-plan): contains the description of an operation, includes tools, machines to be used, process parameters, machining time, etc.
• Op-plan sequence: Summary of a process plan. 67

68. EXAMPLE PROCESS PLANS
Detailed Process Plan
Oper. Routing Summary 68

69. FACTORS AFFECTING PROCESS PLAN SELECTION
• Shape
• Tolerance
• Surface finish
• Size
• Material type
• Quantity
• Value of the product
• Urgency
• Manufacturing system itself
• etc. 69

70. PROCESS PLANNING CLASSIFICATION
MANUAL
COMPUTER-AIDED
VARIANT
GT based
Computer aids for editing
Parameters selection
GENERATIVE
Some kind of decision logic
Decision tree/table
Artificial Intelligence
Objective-Oriented
Still experience based
AUTOMATIC
Design understanding
Geometric reasoning capability 70

71. REQUIREMENTS IN MANUAL PROCESS PLANNING
• ability to interpret an engineering drawing.
• familiar with manufacturing processes and practice.
• familiar with tooling and fixtures.
• know what resources are available in the shop.
• know how to use reference books, such as machinability data handbook.
• able to do computations on machining time and cost.
• familiar with the raw materials.
• know the relative costs of processes, tooling, and raw materials. 71

72. INDUSTRIAL SOLUTION PRODUCT CAD CONCEPT CUTTER CAM PATH
N0010 G70 G 90 T08 M06
N0020 G00 X2.125 Y Z S3157
N0030 G01 Z1.500 F63 M03
N0040 G01 Y4.100
N0050 G01 X2.625
N0060 G01 Y1.375
N0070 G01 X3.000
N0080 G03 Y2.625 I3.000 J2.000
N0090 G01 Y2.000
N0100 G01 X2.625
N0110 G01 Y-0.100
N0120 G00 Z4.000 T02 M05
N0130 F9.16 S509 M06
N0140 G81 X0.750 Y1.000 Z-0.1 R2.100 M03
N0150 G81 X0.750 Y3.000 Z-0.1 R2.100
N0160 G00 X Y M30
CUTTER
PATH
CAM
HUMAN - decision making
COMPUTER - geometric computation, data handling 72

73. PROCESS PLANNING STEPS
Study the overall shape of the part. Use this information to classify the part and determine the type of workstation needed.
• Thoroughly study the drawing. Try to identify every manufacturing features and notes.
If raw stock is not given, determine the best raw material shape to use.
Identify datum surfaces. Use information on datum surfaces to determine the setups.
• Select machines for each setup.
For each setup determine the rough sequence of operations necessary to create all the features. 73

74. PROCESS PLANNING STEPS (continue)
Sequence the operations determined in the previous step.
Select tools for each operation. Try to use the same tool for several operations if it is possible. Keep in mind the trade off on tool change time and estimated machining time.
Select or design fixtures for each setup.
Evaluate the plan generate thus far and make necessary modifications.
Select cutting parameters for each operation.
Prepare the final process plan document. 74

75. COMPUTER-AIDED PROCESS PLANNING
ADVANTAGES
1. It can reduce the skill required of a planner.
2. It can reduce the process planning time.
3. It can reduce both process planning and manufacturing cost.
4. It can create more consistent plans.
5. It can produce more accurate plans.
6. It can increase productivity. 75

76. WHY AUTOMATED PROCESS PLANNING
• Shortening the lead-time
• Manufacturability feedback
• Lowering the production cost
• Consistent process plans 76

77. PROCESS PLANNING Workpiece Selection Process Selection Tool Selection
Machining features
Design
Workpiece Selection
Process Selection
Tool Selection
Feed, Speed Selection
Operation Sequencing
Setup Planning
Fixturing Planning
Part Programming 77

78. VARIANT PROCESS PLANNING
GROUP TECHNOLOGY BASED RETRIEVAL SYSTEM 78

79. PROBLEMS ASSOCIATED WITH THE VARIANT APPROACH
1. The components to be planned are limited to similar components previously planned.
2. Experienced process planners are still required to modify the standard plan for the specific component.
3. Details of the plan cannot be generated.
4. Variant planning cannot be used in an entirely automated manufacturing system, without additional process planning. 79

80. ADVANTAGES OF THE VARIANT APPROACH
1. Once a standard plan has been written, a variety of components can be planned.
2. Comparatively simple programming and installation (compared with generative systems) is required to implement a planning system.
3. The system is understandable, and the planner has control of the final plan.
4. It is easy to learn, and easy to use. 80

81. GENERATIVE APPROACH
A system which automatically synthesizes a process plan for a new component.
MAJOR COMPONENTS:
(i) part description
(ii) manufacturing databases
(iii) decision making logic and algorithms 81

82. ADVANTAGES OF THE GENERATIVE APPROACH
1. Generate consistent process plans rapidly;
2. New components can be planned as easily as existing components;
3. It has potential for integrating with an automated manufacturing facility to provide detailed control information. 82

83. KEY DEVELOPMENTS
1. The logic of process planning must be identified and captured.
2. The part to be produced must be clearly and precisely defined in a computer-compatible format
3. The captured logic of process planning and the part description 83

84. PRODUCT REPRESENTATION
Geometrical information
Part shape
Design features
Technological information
Tolerances
Surface quality (surface finish, surface integrity)
Special manufacturing notes
Etc.
"Feature information"
Manufacturing features
e.g. slots, holes, pockets, etc. 84

85. INPUT REPRESENTATION SELECTION
• How much information is needed?
• Data format required.
• Ease of use for the planning.
• Interface with other functions, such as, part programming, design, etc.
• Easy recognition of manufacturing features.
• Easy extraction of planning information from the representation. 85

86. WHAT INPUT REPRESENTATIONS
GT CODE
Line drawing
Special language
Symbolic representation
Solid model
CSG
B-Rep
others?
Feature based model 86

87. SPECIAL LANGUAGE
AUTAP 87

88. CIMS/PRO REPRESENTATION88

89. GARI REPRESENTATION (F1 (type face) (direction xp) (quality 120))
(F2 (type face) (direction yp) (quality 64))
(F3 (type face) (direction ym) (quality rough))
(H1 (type countersunk-hole) (diameter 1.0)
(countersik-diameter 3.0)
(starting-from F2) (opening-into F3))
(distance H1 F1 3.0)
(countersink-depth F2 H1 0.5) 89

90. CONCEPT OF FEATURE Manufacturing is "feature" based. Feature:
1 a: the structure, form, or appearance esp. of a person
b: obs: physical beauty.
2 a: the makeup or appearance of the face or its parts
b: a part of the face: LINEAMENT
3: a prominent part or characteristic
4: a special attraction
Webster's Ninth New Collegiate Dictionary 90

91. FEATURES IN DESIGN AND MANUFACTURING
A high level geometry which includes a set of connected geometries. Its meaning is dependent upon the application domain.
Design Feature vs Manufacturing Feature 91

92. DESIGN FEATURES • For creating a shape • For providing a function
Slot feature 92

93. MANUFACTURING FEATURES
• For process selection
• For fixturing
Manufacturing
is feature based.
Drilling Round hole
Turning Rotational feature
End milling Plane surface,
Hole, profile, slot
pocket
Ball end mill Free form surface
Boring Cylindrical shell
Reaming Cylindrical shell
End mill a slot 93

94. MANUFACTURING FEATURES (cont.)? 94

95. DATA ASSOCIATED WITH DESIGN FEATURES
Mechanical Engineering Part Design
• Feature Type
• Dimension
• Location
• Tolerance
• Surface finish
• Function 95

96. DATA ASSOCIATED WITH MANUFACTURING FEATURES
• Feature type
• Dimension
• Location
• Tolerance
• Surface finish
• Relations with other features
• Approach directions
° Feature classifications are not the same. 96

97. FEATURE RECOGNITION
Extract and decompose features from a geometric model.
• Syntactic pattern recognition
• State transition diagram and automata
• Decomposition
• Logic
• Graph matching
• Face growing 97

98. DIFFICULTIES OF FEATURE RECOGNITION
• Potentially large number of features.
• Features are domain and user specific.
• Lack of a theory in features.
• Input geometric model specific. Based on incomplete models.
• Computational complexity of the algorithms.
• Existing algorithms are limited to simple features. 98

99. DESIGN WITH MANUFACTURING FEATURES
Make the design process a simulation of the manufacturing process. Features are tool swept volumes and operators are manufacturing processes.
Design
Bar stock - Profile Bore hole
Process Planning
Turn profile
Drill hole
Bore hole 99

100. PROS AND CONS OF DESIGN WITH MANUFACTURING FEATURES
• Concurrent engineering - designers are forced to think about manufacturing process.
• Simplify (eliminate) process planning.
• Hinder the creative thinking of designers.
• Use the wrong talent (designer doing process planning).
• Interaction of features affects processes.
Cons
100

101. BACKWARD PLANNING
101

102. PROCESS KNOWLEDGE REPRESENTATION
• Predicate logic
• Production rules
• Semantic Nets
• Frames
• Object Oriented Programming
102

103. SOME RESEARCH ISSUES
• Part design representation: information contents, data format
• Geometric reasoning: feature recognition, feature extraction, tool approach directions, feature relations
• Process selection: backward planning, tolerance analysis, geometric capability, process knowledge, process mechanics
• Tool selection: size, length, cut length, shank length, holder, materials, geometry, roughing, and finishing tools
103

104. SOME RESEARCH ISSUES (continue)
• Fixture design: fixture element model, fixturing knowledge modeling, stability analysis, friction/cutting force
• Tool path planning: algorithms for features, gauging and interference avoidance algorithms, automated path generation
• Software engineering issues: data structure, data base, knowledge base, planning algorithms, user interface, software interface
104

105. A FEATURE BASED DESIGN/ PROCESS PLANNING SYSTEM
Manufacturing-Oriented Design Features
hole, straight slot, T-slot, circular slot, pocket
counterbore, sculptured surface cavity
Geometric Reasoning
Application-Specific Features (e.g. manufacturing features)
blind slot, through slot, step, etc.
approach direction, feed direction
feature relations: precedence and intersection type
Principle:
Provide designer with the freedom to describe shape -
avoid constraining manufacturing planning
or requiring detailed manufacturing knowledge.
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106. SOME AUTOMATED PROCESS PLANNING EFFORTS
Feature in Design
Features in Process Planning
U. Mass, Dixon: Features-based design for manufacturing analysis of extrusions, castings, injection molding
ASU, Shah: Theory of features study for CAM-I; Feature-mapping shell
Stanford,Cutkosky: feature-based design, process planning, fixturing systems.
Helsinki, Mantyla: systems for design & process planning.
IBM, Rossignac:Editing & validation of feature models; MAMOUR system.
SDRC, Chung, GE, Simmons: Feature-based design and casting analysis.
NIST : Automated process planning
CAM-I, UTRC: XPS-2, generative process planning
U of Maryland, Nau: Semi-generative process planning
GE R & D, Hines: Art to Part
Penn State, Wysk (Texas A&M): graph based process planning
Stanford, Cutkosky: FirstCut, integrated design and manufacturing system based on features.
CMI & CMU: IMW, feature based design, expert operation planning.
U. of Twente, Holland, Kals: PARTS , feature based input, feature recognition, operation planning.
Allied Bendix, Hummel & Brooks: XCUT system for cavity operation planning.
IPK Berlin & IPK Aachen
UMIST, B.J. Davies
U. of Leeds, de Pennington
U. of Tokyo, Kimura
QTC is one of the only efforts that considers design through inspection and the only one that uses deep geometric reasoning to link design and process planning.
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107. SOME APPROACHES
107

108. THE DEVELOPMENT OF CAPP
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