Solid Carbide Drills for CNC Machining

A solid carbide drill is a one-piece tungsten carbide tool, usually coated, that will run at three to five times the cutting speed of an equivalent HSS drill and hold a far tighter hole tolerance while doing it. On the right machine it will often drill a finished-size hole in one operation, removing a separate reaming step from the cycle.

The words on the right machine are doing a lot of work in that sentence. Carbide is hard but brittle. It rewards rigidity and punishes flex, and that is the whole basis of the buying decision.

When a Solid Carbide Drill Pays For Itself

• Volume drilling. The higher tool cost is spread across many more holes, and the cycle time saving compounds on every part.
• Hole tolerance and finish. Where an HSS drill needs a follow-up reaming operation, a carbide drill will often hold the tolerance directly.
• Rigid CNC machines with good coolant. Through-spindle coolant is ideal. Reliable flood coolant is workable.
• Cycle time as the constraint. If the machine is the bottleneck, the speed increase is worth more than the tool cost.