Carbide Drill Bit - Examine Lifecycle Cost

Productivity or cost-per-hole is the biggest trend affecting drilling today. This means that drilling-tool and carbide drill bit manufacturers must find ways to combine some operations and also develop tools that can cope with higher feeds and speeds.

The latest drills have an exchangeable solid carbide drill bit, which offers exceptional economy. Instead of replacing the whole drill body, end users only have to purchase a carbide drill bit, which cost about the same as regrinding a brazed or solid-carbide drill. A carbide drill bit can be swapped out easily and accurately and shops can use a single drill body with multiple carbide drill bits to drill several different hole sizes.

This modular carbide drill bit system reduces drill-inventory costs for tools ranging from 0.47 in. to 0.78 in. (12 to 20 mm) in diameter. In addition, it eliminates the cost of backups needed when regrinding brazed or solid-carbide drills.

In reviewing cost-per-hole, shops should also take overall tool life into account. Typically, shops can regrind a solid-carbide drill bit only seven to ten times, and a brazed drill only three or four times. The steel body of a crown-type drill, on the other hand, lasts for at least 20 to 30 crown changes when used to cut steel.

There also is an issue of productivity. Brazed and solid carbide drill bits must be reground; therefore, shops have a tendency to run these tools slowly to avoid chipping them. But regrinding is unnecessary with exchangeable-head drill bits, so shops can operate them at maximum feed and speed without fear of chipping the carbide material.

New crown-type drills also deliver more consistent tool life than brazed or solid carbide drill bits. In many cases, a reground carbide drill bit will not match the performance of a new drill bit. That is because it is hard to match the cutting edge shape and edge preparation in regrinding. A Carbide drill bit with improper edge preparations will often chip more easily, require more torque or power to operate, or create more heat, thereby shortening tool life.

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