A metal drill bit can drill brass, but there are specific considerations and modifications to ensure effective and safe drilling.
Key Considerations for Drilling Brass
1. Drill Bit Type: Standard twist drill bits can be used, but they often require modifications. Brass tends to grab on sharp edges, which can lead to the drill bit snapping or the workpiece spinning unexpectedly. It is advisable to use high-speed steel (HSS) bits that have been modified to have a flat cutting edge, eliminating the top rake angle that is typically present in standard bits.
2. Geometry Modifications: To improve performance when drilling brass:
- Reduce the Rake Angle: Modify the cutting edge of the drill bit to have zero rake. This adjustment helps prevent the drill from grabbing the brass and improves chip removal.
- Point and Lip Angles:A point angle between 90 and 118 degrees is recommended, along with a lip relief angle between 12 and 26 degrees. These adjustments help balance aggressiveness and reduce binding.
3. Drilling Technique:
Speed and Feed Rate: Brass should be drilled at lower speeds compared to steel, typically around 90-210 m/min. Adjusting the feed rate according to the drill bit's twist rate can also enhance performance.
Clamping the Workpiece: Securely clamping the brass piece is crucial to prevent movement during drilling, which can lead to inaccuracies or accidents.
4.Cooling and Lubrication: While drilling brass, lubrication is generally not required; however, using a lubricant can help reduce friction and heat in some cases. It's important to monitor chip removal-brass should produce small chips rather than long swarf.
By following these guidelines, metal drill bits can effectively drill brass without excessive risk of damage or injury.