Technical Information
Rough Boring Chip Formation
Chip formation when rough boring is very important. An ideal chip should be “C” shaped or look like a six or nine. The chips should also be short as illustrated below.
Proper chip formation is a function of the feed rate and the chip breaker on the insert. Generally the feed rate should be 25% to 35% of the width of the chip breaker.
If the chip does not break, increase the feed rate provided that the following conditions exist:
- The part and the fixture are sufficiently rigid;
- The machine has sufficient horsepower;
- The machining allowance does not exceed the stated maximum;
- The tool is not overly long.
If the chip does not break with the increased feed rate, it may be necessary to change to an insert with a smaller chip breaker.
It is important to remember that the thin, wide chip produced from a low feed rate and a large machining allowance is difficult at best to break. As a general rule, the feed rate should be 10% to 30% of the machining allowance.
