Aspect Ratio for Deep Pocket Milling

Core Principle

The ratio of a pocket's depth to the tool's diameter (or pocket width) is a key driver of cost and feasibility. High ratios mean long, slender tools prone to vibration and breakage.

Depth-to-Diameter Ratio Guidelines

• <3:1 - Economical Zone: Standard tools, fast machining
• 3:1 to 6:1 - Achievable: Increasing cost, longer tools, slower feeds
• >6:1 - Difficult Zone: Cost increases sharply, special tooling required
• >10:1 - Very challenging: May require EDM or other processes

Design Recommendations

• Design pocket depths <4 times tool diameter when possible
• For deep pockets, use large internal radii to allow bigger, more rigid tools
• Consider alternative manufacturing methods for extreme aspect ratios