The spindle was set up from Matsuura for high speed milling at 15,000 rpm but the rear roller bearing installed by the last person to rebuild the spindle was rated for a top speed of 11,000 rpm. Here is a picture of the results:
Possible cause of failure:
• Spindle arrived seized; rear roller bearing had catastrophic failure. Inner and outer races were cracked.
• Rear roller was rated for a max. rpm of 11,000, the spindle speed is 15,000.
• Drawbar force is below customer’s standard for a Big Plus taper. It has 1550lbs of force, customer requirements are 1800lbs minimum.
• Taper and face are a little worn, The taper only has 3-6 micron’s run out on the test bar with good contact in the taper and good face contact.
• Spindle has been changed from grease injection to grease pack previously.
• Gripper fingers have slight wear but are functional (we will use as is)
• Clean, inspect overall dimensions.
• Replace bearings with a triplex to make it more rigid, speed will decrease to 12,000 rpm.
• Replace bellevilles, orings, and screws.
• Machine the spacer to allow the triplex.
• Adjust preload, balance, assemble and break in. Final quality control inspection.
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Catastrophic bearing failure was the main cause of this spindle malfunction
Continue reading to learn how Northland Tool performed this repair and converted a Weiss GHK 176239 spindle from grease-injected to permanent grease lubrication…