Chip Load

Chip load is the thickness of material removed by each cutting edge per revolution, typically expressed in inches per tooth or mm per tooth. Also called feed per tooth (FPT), it is calculated as Feed Rate ÷ (RPM × Number of flutes). Proper chip load ensures efficient shearing and heat removal, while incorrect values lead to rubbing, burning, or tool overload.

On the shop floor, chip load is the critical link between spindle speed, feed rate, and flute count, determining how aggressively the tool cuts rather than rubs. A correct chip load produces a proper chip that carries heat away from the cut zone, preventing premature wear, burning in wood, or melting in plastics. Machinists use chip load to tune feeds and speeds for the material, then verify performance by observing chip shape, surface finish, burr formation, and tool temperature during a test cut. In millwork and CNC routing, chip load is especially important for plywood, MDF, hardwood, and plastics: too little chip load scorches wood fibers or melts thermoplastics, while too much can overload the bit, causing tear-out or breakage. Operators adjust feed or RPM while monitoring chip form and cut quality to achieve optimal results.