1. When is it time to have a tool re-sharpened? When the cutting edge becomes dull. Some things to look for are: surface finish quality will decrease; the amount of horsepower necessary to cut will increase; and the noise level may increase.

2. What is the major cause of tools becoming dull? Heat is the major reason tools break down and become dull. To reduce the amount of heat, increase the chipload or reduce the RPM. This will keep the heat in the chip and remove it from the part. After a cut, the tool should be cool to the touch.

3. What should be kept in mind with regards to  feed and speed? When fine-tuning a CNC router, start at the low end of the feedrate recommendation. Use the feedrate override to increase feed rate until:

1. The edge finish deteriorates because of tool chatter.

2. The machine defaults to a slower speed due to tight radii.

3.  The part moves or is pushed off the vacuum.

After determining the maximum feed, lower the spindle speed until the edge finish once again deteriorates. Then adjust the spindle speed higher until the finish becomes acceptable. By adjusting feed and spindle speed, maximum productivity and tool life is reached.

Source: LMT Onsrud. For more information visit Onsrud.com or call (800) 234-1560.

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