Hydromat Collet Housing Wear Problem


The intention of this bulletin is to raise awareness of the performance decline that occurs over time on all collet type Hydromats due to the collet housing wear. Understanding this condition will help to troubleshoot work holding challenges and performance issues when switching collet brands from within OEM product lines or other collet brands. This information will help you to identify if you have this problem and the options to remedy this condition and return equipment back to original equipment performance.

Do you have this problem?

If you are experiencing part holding issues or collet breakage with your Hydromat, collet housing wear may be causing this. You will have sufficient wear to reduce holding performance if:

  1. The equipment is older with many cycles
  2. Has ran or is running water soluble cutting fluids
  3. The material machined is abrasive i.e. powdered metals, aluminum some steels
  4. If you have only been running collets with the split area relieved
  5. Have switched to another brand of collet and experienced breakage or work holding performance decline

The Issue

Collets that have the area around the collet split relieved, creates an area of the collet that will have all of the collet clamping forces and where the wear in the collet housing will occur. There is an argument that collets without this split relief will reduce the wear on the collet housing due to the larger area of contact available. Reduced collet clamping performance and breakage will occur if:

  1. Collets with split relief does not match the wear in the housing
  2. Collets without split relief are used



Using a dial indicator in a spindle, sweep the housing bore about 2mm from the face. Sudden changes that correlate to the collets splits will identify the housing wear. testing


Both images below show the effects of detrimental collet wear



There are a few options to choose from to resolve this problem:

  1. Rework the collet housings
    1. Economical
    2. Lengthy machine down time is required
    3. Part stop position relative to the collet will change
  2. Replace the collet housings
    1. Expensive
    2. Lengthy machine down time is required
    3. Collet performance back to original design capabilities
  3. Rotate the collet splits 180° so that the center of collet sections are now contacting the area of the collet housing that is not worn
    1. No additional cost if you are buying collets anyhow
    2. No machine downtime – other than collet installation
    3. Collet performance back to original design capabilities


Understanding this issue and applying the correct solution will solve work holding challenges, and allow you to use any collet brand effectively.

Core Powered can help you identify if you have worn housings that are affecting machine performance. Then we can help you identify which solution is right for you, and provide the parts or repair for this.

For more information email us sales@corepoweredinc.com or call 905-362-9377