Core Principle

Turning (Lathe) creates round parts by rotating workpiece against stationary cutting tool. Milling creates square/complex parts by rotating cutting tool against stationary workpiece.

Design for Turning (Rotational Symmetry)

• Parts should be axially symmetric
• Features like grooves/steps perpendicular to central axis
• Ideal for: shafts, pins, bushings, cylindrical components
• Generally faster and cheaper than milling same shapes

Design for Milling

• Parts can be any shape
• Consider tool access from top or sides
• Avoid deep, narrow slots
• Better for complex, non-round geometries

Selection Rule: If part is primarily cylindrical, design as turned part for faster, cheaper manufacturing.