How HSS Twist Drills Are Made

Hi everyone, I’m Lynn from Jiateng Tools. Let me walk you through how an ordinary piece of high-speed steel is transformed into a professional fully ground drill bit that cuts through metal with ease. This is a precision journey made up of ten interlocking processes.

First, we cut the raw material into sections with a 0.25 mm diameter allowance and a 0.40 mm length allowance. Before cutting, a dedicated device automatically straightens the raw material so every cut bar is straight.

Next comes chamfering. We grind the drill tip to a standard 130 degrees as the foundation for later sharpening. The shank receives a 45-degree flat chamfer to remove sharp edges and simplify assembly.

During quenching, the high-speed steel is heated in a furnace at 1,100–1,150°C, followed by four tempering cycles at 420°C, each held for 1.5–2 hours. The target hardness rises from approximately 25 HRC to 63–65 HRC.

After quenching, five grinding operations remove excess material, refine the outer circle and calibrate the final dimensions. Flute grinding then shapes the helical flutes at around 30 degrees, with web thickness and flute width controlled for chip evacuation.

Edge cleaning balances cutting sharpness with edge strength. The point is then ground to a 135-degree split point to improve centering and chip breaking compared with a conventional 118-degree point.

Fine finish grinding polishes the surface. Manual inspection removes products with cracks, chipped edges or other visible defects after in-process checks have confirmed dimensions and angles.

Finally, laser marking adds the model, specification, material and logo. The finished fully ground drill bit is then ready for identification, packing and delivery.