Rotary broaches are made from durable high speed steel. Smaller broaches, such as a 1/8” hex broach, can make over 1,000 parts in aluminum and other soft metals. Larger forms, such as an 8mm square, may only last into the mid 100’s. Calculating tool life is very difficult due to the number of variables in the rotary broaching operation. Some upgrades can extend tool life, such as premium broach material, coatings, spun-ground diameter and pressure relief holes. However, controlling the following variables will give you a good start at improving the tool life of your rotary broaches:
- Chamfer to the sharp corner or major diameter of the broach
- Minimize broaching depth
- Plenty of room for chips is required
- An oversize pilot hole is key for reducing chip size and separating curling chips
- Machine capability
- No work hardening from the drill
- Sharp drills are required for smooth pilot holes
- Broach tool alignment or concentricity to the work piece
