Machining Process

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Machining Process
1. Concept
- Any type of materials could be cut ceramic ?
- There is a family of machining processes
abrasive, etc
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Various types of machining processes
Drilling
Turning
Peripheral milling
Face milling
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What function and quality level can machining
processes achieve?

• - Dimension accuracy 0.025 mm

- Surface quality 0.4 um
- Any shape
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What are generic features in any machining
operations to make cutting processes work?
- Two motions tool motion and work motion
- Primary speed and feed (rate)
- Relative motion between the two motions
generates mechanics to form chips and remove them
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2. Cutting Tools
Cutting Mechanisms
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2. Cutting Tools
Major cutting parameters
Material Removal Rate MRR v f d
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3. Engineering Analysis

• Machine equipment to do material removal process
  
• theory of chip formation, energy,
  and power

- Tool life tool failure causes quality problem
- Productivity
- Quality assurance
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3.1 Theory of chip formation
Orthogonal Cutting Model converts 3d to 2d

• Chip Thickness ratio, r to/tc (tc gt to)
• MRR vtow (instead of v f d )

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3.1 Theory of chip formation
E- Efficiency that accounts for loss of the
machine tool
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3.2 Tool life

• Fracture failure force becomes excessive,
  causing sudden brittle fracture

- Temperature failure temperature is too high,
causing the material at the tool point to soften
- Gradual wear (1) crater wear (2) flank wear
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- The objective of selecting tools should ensure
that only the gradual wear mode will occur
- Tool design materials and geometry
- Except for tool design parameters (system
parameters), tool life is a function of operating
parameters
(d) (f) (v)
Cooling methods ( fluids)
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3.3 Productivity
Productivity is also called removal rate which is
computed by the following equation
(d) (f) (v)
3.4 Quality
System parameters
Operating parameters
Example - Rough cutting (f 0.4-1.25mm/rev
d2.5-20mm) - Finish cutting (f
0.125-0.4mm/rev d0.75-2.0mm)
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Summary
System parameters
Operating parameters
Tool
(d) (f) (v) -gt Power
Material
Cooling methods
Goal Select operating parameters to ensure no
failure with the whole system and satisfactory
quality