Drilling and Boring Tools

Before drilling, create a center hole or use a pilot drill to prevent the drill bit from running off-center or slipping.

Select the linear speed and feed rate per revolution based on the workpiece material. When machining stainless steel or titanium alloys, the linear speed should not be excessively high (10–30 m/min), and "peck drilling" should be employed to facilitate chip evacuation.

Prioritize the use of internal-coolant drills; high-pressure coolant flows directly to the cutting zone, preventing chip clogging that could lead to drill breakage.

The height difference between the main cutting edges must be ≤ 0.03 mm; otherwise, the drilled hole may be oversized or misaligned.

Prior to boring, a pre-drilled or rough-bored hole is required; the single-sided allowance should be between 0.3 mm and 1.5 mm. An allowance that is too large increases the risk of tool vibration, while one that is too small results in poor surface finish due to excessive friction.

The tool tip must be aligned to the exact center height of the workpiece (with a tolerance of ≤ 0.05 mm); otherwise, the resulting bore will be tapered or elliptical.

For high-speed boring operations (> 8000 rpm), dynamic balancing is mandatory. The overhang length of the boring bar should be minimized-ideally maintaining a length-to-diameter ratio of ≤ 4-to prevent chatter marks.

The fine-adjustment mechanism must be locked immediately after setting to prevent cutting forces from causing dimensional drift.