Machining Operations by Ed Red Objectives Introduce machining operations terminology

Peripheral milling cutting positions

• Face milling cutting positions

• Full face cut

• Offset face cut

• Milling cutter time analysis

• Spindle rpm related to cutter diameter and speed:
• N (rpm) = v/( D)
• Feedrate in in/min:
• fr = N nt f
• where f = feed per tooth
• nt = number of teeth
• MRR is
• MRR =w d fr

• Milling time analysis

• Slab milling:
• Approach distance, A :
• A = d (D-d)
• Time to mill workpiece, Tm:
• Tm = (L + A)/fr
• Face milling:
• Allow for over-travel O where A = O:
• Full face A = O = D/2
• Partial face A = O = w (D – w)
• Machining time:
• Tm = (L + 2A)/fr

• Milling time analysis - example

• Problem statement:
• A face milling operation is performed to finish the top surface of a steel rectangular workpiece 12 in. long by 2 in. wide. The milling cutter has 4 teeth (cemented carbide inserts) and is 3 in. in diameter. Cutting conditions are 500 fpm, f = 0.01 in./tooth, and d = 0.150 in. Determine the time to make one pass across the surface and the metal removal rate during the cut.

• Milling time analysis - example

• Solution? Numbers?

• Full face A = O = D/2
• Machining time Tm = (L + 2A)/fr
• Metal removal rate MRR = w d fr
• Feedrate in in/min fr = N nt f
• N (rpm) = v/( D)

• Tolerance by process

• Surface finish by process

• Surface finish by geometry

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