High-Speed Steel (HSS) drill bits are widely used for drilling a variety of materials, including steel, aluminum, and plastic. But to achieve the best results and extend the life of your drill bits, it’s essential to use the correct hss drill speeds (RPM) and feed rate (mm/rev or IPM).
What Is HSS Drill Speeds and Feeds?
Drill speed refers to the rotational speed of the drill bit, measured in revolutions per minute (RPM). The right RPM depends on the material being drilled:
Suggested Drill Speeds for Different Materials
Different materials require different cutting speeds. Use this guide to match your RPM to the material you’re drilling when using HSS bits.
| Material | Recommended RPM (for 10mm HSS drill bit) |
|---|---|
| Mild Steel | 800 – 1000 RPM |
| Stainless Steel | 300 – 500 RPM |
| Aluminum | 1000 – 1500 RPM |
| Plastic | 1500 – 2000 RPM |
Tip: Softer materials need higher RPMs; harder materials need slower RPMs.
What Is Feed Rate?
Feed rate refers to the speed at which the drill bit moves into the material, usually measured in mm/rev (millimeters per revolution) or IPM (inches per minute).
- For HSS drills:
0.05 – 0.2 mm/rev is typical for manual or CNC drilling depending on material hardness and drill diameter.
Recommended RPM for HSS Twist Drill Bits
To ensure optimal drilling performance and extend tool life, it’s important to match the drill bit size with the correct RPM (Revolutions Per Minute). Refer to the table below for recommended speeds when using HSS twist drill bits:
Twist Drill Bit Speed Chart (HSS)
| Drill Size (mm) | Speed (RPM) | Drill Size (mm) | Speed (RPM) |
|---|---|---|---|
| 1mm – 2mm | 3000 – 1800 | 8mm – 9mm | 500 – 400 |
| 2mm – 3mm | 1800 – 1400 | 9mm – 10mm | 400 – 350 |
| 3mm – 4mm | 1400 – 1000 | 10mm – 11mm | 350 – 300 |
| 4mm – 5mm | 1000 – 800 | 11mm – 12mm | 300 – 280 |
| 5mm – 6mm | 800 – 700 | 12mm – 13mm | 280 – 250 |
| 6mm – 7mm | 700 – 600 | 14mm | 220 |
| 7mm – 8mm | 600 – 500 | 15mm | 200 |
Best Practices
- Use cutting fluid for metals to reduce heat and wear.
- Reduce speed by 30–50% when drilling stainless steel.
- Start slower and adjust based on chip shape and surface finish.
- Use a pilot hole for large diameters.
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