1. Process Engineering

2. Contents
3.0 Introduction
3.1 Experience-Based Planning
3.2 Decision Tables and Decision Trees
3.3 Process-Capability Analysis
3.4 Basic Machining Calculations
3.5 Process Optimization
3.6 Conclusion
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3. 3.0 Introduction
3.1 Experience-Based Planning
3.2 Decision Tables and Decision Trees
3.3 Process-Capability Analysis
3.4 Basic Machining Calculations
3.5 Process Optimization
3.6 Conclusion
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4. Introduction
• Manufacturing
• Raw material → Finished product
• Process capability ismachine tools scientific knowledge for
= historic and ??
each process (≠machine tools)
historic
Process
Process
Capability
Scientific knowledge
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5. Process Capability
• Three levels of Process Capability
Universal Shop Machine
-level -level -level
• Important parameters
• The shapes and sizes
• The dimensions and geometric tolerances
• The material removal rate
• The relative cost
• Other cutting characteristics/constraints
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6. 3.0 Introduction
3.1 Experience-Based Planning
3.2 Decision Tables and Decision Trees
3.3 Process-Capability Analysis
3.4 Basic Machining Calculations
3.5 Process Optimization
3.6 Conclusion
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7. Experience-Based Planning
"The accumulation of experience is knowledge "
• Problem of Experience-Based
• requires a significant period of time to accumulate
• represents only approximate, not exact knowledge
• is not directly applicable to new processes or new systems
• Machinist Handbooks
• has long been a standard manufacturing practice
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8. 3.0 Introduction
3.1 Experience-Based Planning
3.2 Decision Tables and Decision Trees
3.3 Process-Capability Analysis
3.4 Basic Machining Calculations
3.5 Process Optimization
3.6 Conclusion
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9. Decision Tables and Decision Trees
• Describing the actions associated with conditions
• Help systematize decision making
• Translate each other
• Difference
• Ease and elegance of presentation and programming when a
computer is used Condition
Action
Stub Entries
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10. Decision Table
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11. Decision Table
• When constructing, consider factors
• Completeness, Accuracy, Redundancy
• Consistency, Loops, Size
• Merge
Merge
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12. Decision Table
• Table splitting and parsing
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13. Decision Tree
• Single root, Node, Branch
• Branch – ‘IF’, branches in series – ‘AND’
Node
Branch
Root
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14. 3.0 Introduction
3.1 Experience-Based Planning
3.2 Decision Tables and Decision Trees
3.3 Process-Capability Analysis
3.4 Basic Machining Calculations
3.5 Process Optimization
3.6 Conclusion
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15. Information Required to Make the Decision
Shape
Size Limitation
Capability
Tolerance
Surface Finish
Cutting Force
Limitation
Power Consumption
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16. Process Boundaries
• One way to represent process capability
• Limiting size, tolerances, surface finish
• System-dependant
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17. 3.0 Introduction
3.1 Experience-Based Planning
3.2 Decision Tables and Decision Trees
3.3 Process-Capability Analysis
3.4 Basic Machining Calculations
3.5 Process Optimization
3.6 Conclusion
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18. Feed and Feed Rate
• Feed
• The relative lateral movement between the tool and the workpiece
during a machining operation (= thickness of the chip)
• Feed in turning and drilling
• The advancement of the cutter per revolution of the workpiece
(turning) or tool (drilling)
• Unit - ipr (inch per revolution)
• Feed in milling
• The advancement of the cutter per cutter-tooth revolution
• Unit - inch per revolution per tooth
• Feed rate - ipm (inch per minute)
• Equation (3. 17)
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19. Machining
• Cutting Speed
• The maximum linear speed between the tool and the workpiece
• Equation (3. 18)
• Depth of cut
• Width of the chip
• Equation (3. 19)
• Metal-Removal Rate
• How fast material is removed from a workpiece
• Equation (3. 20) ~ (3. 28)
Short processing time
MRR is Large ( )
Short the life of cutter
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20. Machining Time
• Total amount of time
• Parameter
• The length of the workpiece
• Overtravel of the tool for clearance
• The number of passes required to clear the volume
• Equation (3. 29) ~ (3. 31)
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21. Tool Life
• Erosion (Wear)
• Crater wear
• High Temperature
• Flank wear
• Friction
• Breakage (Catastrophic Failure)
• F. W. Taylor
• Tool-life Equation
• Relation of Tool life and Cutting speed
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22. Machining Force and Power Requirements
• Important considerations in selecting process parameters
(feed, speed, and depth of cut)
• Not limiting values
• Machining force
• Equation (3. 35) ~ (3. 37)
• Cutting power
• Equation (3. 38) ~ (3. 39)
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23. Process Parameters
• Feed, Speed, Depth of cut
• Process selection becomes an iterative procedure
• Process Selection
• Machining parameters are adjusted to accommodate the system
constraints
• Parameters affects the time and cost
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24. 3.0 Introduction
3.1 Experience-Based Planning
3.2 Decision Tables and Decision Trees
3.3 Process-Capability Analysis
3.4 Basic Machining Calculations
3.5 Process Optimization
3.6 Conclusion
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25. Process Optimization
Short processing time
MRR is Large ( )
Short the life of cutter
• Tool has been worn → Replace
• Trade-off between increased machining rate and machine
idle time
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26. Single-Pass Model
• Assume that only one pass to produce the required
geometry
• The depth of cut is fixed
• Constraint
• Spindle-speed constraint
• Feed constraint
• Cutting-force constraint
• Power constraint
• Surface-finish constraint
• Equation (3. 40) ~ (3. 47)
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27. Multipass Model
• Assumption of single-pass model is relaxed
• Can be reconstructed into a single-pass model
• The depth of cut is a control variable
• Constraint
• Spindle-speed constraint
• Feed constraint
• Cutting-force constraint
• Power constraint
• Surface-finish constraint
• Depth-of-cut constraint
• Equation (3. 63) ~ (3. 67)
• No general solution method
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28. 3.0 Introduction
3.1 Experience-Based Planning
3.2 Decision Tables and Decision Trees
3.3 Process-Capability Analysis
3.4 Basic Machining Calculations
3.5 Process Optimization
3.6 Conclusion
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29. Conclusion
• Information of process-planning system
• Design knowledge – Chapter#2
• Process knowledge – This Chapter (Chapter#3)
• Process planning
• Procedure that matches the knowledge of the processes with the
requirements of the design
• Process Capability
• Decision logic
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