The most common cause of inadequate tool life or breakage trickles back to collet maintenance. A collet is the mechanism that holds the router bit in place and is made up of six key components. Taking some time to inspect and clean the collet system will in turn increase productivity and decrease overall costs.
1. Internal Collet Clamping Surfaces
The inside of the collet is a key component in the tool holder assembly. Resin travels up through the slits in the collet and begins to collect on the inside. If the resin is not removed, the build-up interferes with the grip of the collet to the tool shank. This loss of grip causes the tool to shift, resulting in slippage when inside the collet. Slippage can cause fretting which is the build-up of resin on the shank of the tool.
2. Internal Spindle & Collet Taper
Resin builds up on the inside taper of the spindle and tool holder so it is critical to clean these surfaces between each tool change. Felt brushes are ideal for removing short-term build-up.
3. External Collet & Tool Holder Taper
The outside taper of the collet and tool holder should be inspected regularly; clean any build-up noted. Brass brushes make excellent cleaning tools, and for minor resin build-up felt cloths work best.
4. Thrust Bearings
Collet nuts may have a thrust bearing connected to its inside taper serving to reduce friction between the collet and the nut as the nut is tightened. This bearing must be kept clean and in working order otherwise rough movement is likely to occur.
5. Tool Holders
The tool holder is what holds the collet and the collet keeps the routing bit in place. When a CNC machine is switching tools, the tool holder is what is picked up initially because it holds the actual routing bit. Fretting can cause inconsistent gripping in the taper which can diminish tool life. If build-up is not taken care of, premature spindle failure can occur.