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Terrible bit life over a short amount of time



I am deeply struggling with very short bit life cutting melamine panels at my business.  First, some quick info:

Machine: Cosmec Conquest 5 x 10 CNC, spindle run-out measured at 0.00025″

Material: 3/4″ melamine panels, cut in one pass

Tooling: 3/8″ 2-flute compression bit (Onsrud 60-123MW)

Speed: 18,000 RPM

Feed rate 675 IPM (nominally confirmed by measuring the time to move 10ft)

Chip load calculates to 0.01875″ per flute.


While I’m not sure of the exact life we were getting in the past, it was on the order of at least 30 sheets.  It is now 3 sheets.  We do not know of any change, either in material, bits or program that would cause this change.  The spindle run-out has been checked and found to be quite good, the collets and tool-holders have been swapped, though not assuredly with brand new, but no reason to believe they are “bad”. I did find a worn bearing in the X-drive, which has been replaced.  The pull stud is tight and the HSF spindle seems to be pulling it tight, though not sure how to go about testing this.

Most recently, we saw chipping on the top surface by the third sheet and could see with the naked eye a nick in the carbide at a location that corresponds to the top surface of the material.  At this point, I am considering renting a high speed camera to see what is going on at the bit, but am otherwise out of ideas.  Any help from anyone (please!).




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