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The following information is directed toward indexable carbide
tools but it can be applied to many other cutting tools, as well.
It provides some basic guidelines designed to serve as a
starting point for safe and reliable performance. Contact your Allgeheny Tool & Supply sales engineer for specific application assistance.
Material "K" Factors
Rigidity. Use the most rigid cutter possible. This usually means the cutter with the largest diameter and shortest length. Use the best adaption possible. Integral tapers, such as a 50 V-flange, are better than straight shanks. When selecting straight shank tools, use a cutter with the largest diameter shank possible and a holder with the shortest length possible.
Effective cutting edges. When calculating feed rate, use the effective number of inserts. In extended flute cutters, the effective number of inserts is not the number of rows. Use the effective number listed with the specifications for each series of tools.
Chip load. Carbide cutting tools have to take a “bite” to cut. Be sure to cut with an adequate chip load. Light chip loads can contribute to chatter, causing a cutter to “rub” instead of “bite.” This can also result in poor tool life. As a general rule, chip loads should not be less than .004". Also, be sure to use Radial Chip Thinning Factors (RCTF) when calculating feed rates.
Chip recutting. Unlike HSS, carbide cutting tools cannot recut chips. Recutting chips will damage carbide. To evacuate chips, use air or coolant depending on the material being cut.
Chip Thinning. Occurs when chips are thinner than the feed rate of cutter. E.g. the feed rate = 0.010 IPT, chip thickness = 0.006".
Coolant. Generous amounts of coolant are required when low thermal conductivity, work hardening, and chip welding tendencies are evident. Use coolant only when necessary. Some materials cut better dry. In some applications, coolant causes thermal cracking of inserts and poor tool life.
Feed rates. Reduce feed rates by 50 percent when entering or exiting a cut. Since fewer inserts are engaged in the work, pounding can occur. Reducing feed rates will reduce the shock of the interrupted cut and contribute to longer tool life.
When entering a corner during pocket milling, a larger portion of the cutter’s diameter is engaged. Power requirements and tool deflection increase. To compensate, program a reduced inter- polated feed rate. Alternately, drill or plunge the corner prior to milling.
Cutter rotation. Climb cut whenever possible.
Carbide is designed for climb milling and will not generally
perform as well when conventional cutting. Conventional cutting may
on older machines to minimize backlash. It can also extend tool life in sandy, scaly, or torch-cut surfaces as the cutting edge enters into cleaner, softer material.