Neglecting the maintenance of collets, tools, and your machine, results in a dramatic drop in performance, which reduces productivity and increases costs due to higher scrap rates and potential machine downtime. 

Consequences include tool slippage, tool run-out and scoring of both the holder and the tool shank. The lack of collet maintenance/replacement is one of the most common causes of premature tool failure. 

The typical life span of a collet ranges between 400-600 hours, which roughly translates to between two and three months when the collet is used eight hours a day. 

When inspecting your collet, metallic damage, such as bell mouthing or burrs, should be checked with every tool change. If damage is visible, the collet should be discarded and replaced.

By replacing your collet as suggested, you ensure your operation runs consistently, cut quality is maintained, and the life of your cutting tools are prolonged. 

When replacing the collet, make sure the flute fade out and does not enter the collet. Compacting debris inside/into the collet flutes can cause run out and counter pressure to the clamp force of the spring. 

To ensure proper clamping, the tool shank should fill, at the minimum, 80% of the depth of the collet. Typically, collets are rated to accommodate this variance and on certain conditions, high-precision collets, i.e. tighter tolerances, are available.

Cleaning your collet is equally as important as checking for metallic damage. Over time, dust and swarf created during cutting will accumulate on your collet, tools, tool holder, collet nut, and spindle. 

An excessive build-up of dirt will cause the tool to cut in an elliptical fashion, which will invariably reduce tool life and result in poor cut quality. Collets, tool holders, and the collet nut should be regularly inspected and cleaned using a lint-free cloth, denatured alcohol and protected with a metallic anti-rust lubricant if CNC holders are not stainless steel.

Cleaning instructions:

• Spray a rust-free cleaner on the surface and allow it to soak for a minute (or soak in lacquer thinner if heavy pitch).
• Use a collet brush kit to clean the surface thoroughly.
• Rinse off using denatured alcohol. Feel the surface using your fingers to make sure the surface is clean.
• Spray a small amount of anti-corrosive spray to prevent rusting.
• Replace if any scoring, burrs visible, or tool slippage has occurred. Best to replace main-use collets every quarter as needed.

Tool holder cleaning
Keeping your CNC tool holders clean is just as important as keeping your cutting tools sharp. Proper maintenance not only helps a CNC machine run most efficiently, but it can also prevent tool breakage and premature wear of the holder, locking nut seizures, and rust. 

Inspection and cleaning of CNC tool holders and spindles should be done frequently. A proper inspection includes taking the tool holder apart and cleaning it. Residue can be left behind by which affects the efficiency of the cutting process.

When cleaning your machine parts, only use lint-free dry cloths. Wipe the entire holder carefully. Then apply a light coat of penetrating rust inhibiting lubricant. This helps to prevent rust and keeps corrosion to a minimum. Use only wiping tools made specifically for cleaning your machine. 

In summary:

1. Use the air nozzle to loosen and remove any build-up or debris.
2. Wipe holder/tool with lint-free cloth or cleaning kit. 
3. Use pitch/lubricant degreaser spray for your industry if the first two steps are not satisfactory. Wipe clean.
4. Clean threads of holder and nut with nylon or bronze bristle brush.
5. Wipe clean entire holder and nut with denatured alcohol removing residue.
6. Apply anti-corrosion spray to prevent any rust on your tools.

Source:  CNC-Tool.com. For information on CNC-Tool, call 636-447-3439 or visit CNC-Tool.com.