Frequently Asked Question

Can someone give me the procedure on how to check if your spindle is worn or not.
Last Updated 7 years ago

This is a good question, and the preventive maintenance may save a lot of cost associated with spindle failure.

Whenever you receive a new machine or spindle, you need to measure its Frequency Response Function (FRF) by using a clean, master tool holder with a blank carbide cylinder. The stick-out must be kept constant and set. After the hammer test, you need to store the FRF data in a safe database. Periodically, depending on how much you abuse the spindle by running machines under chatter vibration, you need to check the magnitude of the FRF or magnitude of the imaginary parts of the FRF. Any increase in FRF magnitude means that the chatter vibration free depth of cut is reduced proportionally. If the magnitude of the FRF increased by 20% at any peak (natural frequency) , that means you lost 20% of the dynamic stiffness and the depth of cut needs to be reduced accordingly if you were machining close to the stability lobe borders. The loss of stiffness may be due to wear of the spindle’s taper interface or bearings. It is up to you and spindle builder how far you can tolerate the wear of the bearings and spindle. I would not let it develop beyond 30%, but this number is totally dependent on each spindle builder. We wish that they know about the procedure and let their customers know. Every spindle has its own durability strength, and we cannot make assumptions about it.

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