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Machining processes
2.810 Fall 2003 Professor Tim Gutowski

Outline
Basic Machine Configuration1 Basic Mechanics1 Geometry1,3 Production machining1,2,3,4,5 Environmental Issues

Readings
1. Kalpakjian Ch.20-26 2. “Simplified Time Estimation Booklet for Basic Machining Operations” 3. Design for Machining handout 4. Single minute exchange of dies (SMED) handout 5. “A Job Shop” handout

Outline
Basic Machine Configuration1 n Single point machining w Turning, boring, trepanning, planing

n

Multiple point machining w Drilling, milling, reaming, sawing, broaching, grinding

Machining processes
Turning
*

Grinding
V D Grinding wheel Grains

v

Workpiece

Milling
* Cutter Arbor Spindle Spindle Shank End mill

Arbor

Horizontal Slab milling

Face milling

End milling

* Source: Kalpakjian, “Manufacturing Engineering and Technology”

Machine Tools
* * Spindle speed selector Headstock Spindle Ways Cross slide Carriage Feed change gearbox Center Tailstock quill Tailstock

Horizontal-spindle surface grinder

Compound rest and slides (swivels)

* Apron Bed Lead screw Feed rod Column

Head

Table Saddle Knee

Basic Lathe

Vertical-Spindle Mill
* Source: Kalpakjian, “Manufacturing Engineering and Technology”

Base

Outline
Basic Mechanics1 n Power, Forces Heat, Tool materials, Rate limits New Technology to reduce these effects See Video on Plastic Deformation

n

n

Basic Machining Mechanism
• d(work) F ⋅ V = Power = = work dt

Chip
- +

tc

•

work
•
V

Rake angle α = specific energy = u S

vol u S = u plastic work (65 to 80%) + u friction u p = ∫ σ dε ≅ τγ 1 u p ≅ τγ ≅ H × ( 2 − 4) 6
Approximation us ~ H (Hardness)

Tool t0 φ

2≤γ ≤ 4

Shear plane

Shear angle Workpiece

Specific energy, uS

Basic Machining Mechanism
Hence we have the approximation;

Power = Hardness * MRR
MRR is the Material Removal Rate or d(Vol)/dt Since Power is P=F*V and MRR can be