Tips for Faster Cuts and Longer Tool Life
Stainless steel is one of the most common materials encountered in fabrication, maintenance, and industrial environments. It's strong, corrosion resistant, and durable, but it can also be one of the most frustrating materials to drill if the correct technique isn't used.
Many drilling problems stem from one simple issue: heat. Drill too fast, use insufficient lubrication, or apply excessive pressure, and stainless steel can quickly work-harden, making it even more difficult to cut.
Fortunately, with the right tools and technique, drilling stainless steel can be fast, efficient, and predictable. Read on below for some key tips to help you achieve better results or watch our technical guidance video.
1. Secure the Drill Bit Correctly
Before making the first cut, make sure the drill chuck is gripping the flats on the drill bit shank rather than the curved surface.
Many cobalt drill bits, like the HMT TurboTip Cobalt Jobber Drill Bit, feature machined flats specifically to provide a secure grip. If the chuck is tightened onto the rounded section of the shank, the bit can slip under load, reducing performance and potentially damaging both the bit and the workpiece.
A correctly secured drill bit provides better torque transfer and helps maintain control throughout the cut.
2. Slow Down When Drilling Stainless Steel
One of the most common mistakes when drilling stainless steel is using excessive speed.
Unlike softer materials where higher RPMs often improve productivity, stainless steel requires a slower, more controlled approach. Excessive speed generates friction and heat, causing the material to work-harden and dulling the cutting edges of the drill.
For cordless drills, use the low-speed, high-torque gear setting for the main drilling operation. Controlling speed with the trigger rather than running at full throttle helps minimise heat build-up and extends tool life.
The general rule is simple:
If the drill is getting excessively hot, it's probably running too fast.
3. Use Cutting Lubricant Generously
Lubrication plays a vital role when drilling stainless steel.
Applying a high-quality cutting fluid such as BioCut Blue directly into the drill flutes helps:
- Reduce friction
- Carry heat away from the cutting edge
- Improve chip evacuation
- Extend drill life
- Produce cleaner holes
Apply lubricant before beginning the cut and continue to replenish it throughout the drilling process. When drilling larger holes, having a second person periodically apply additional lubricant can make a noticeable difference to performance.
4. Apply Firm, Controlled Pressure
Drilling stainless steel requires a balance between speed and feed pressure.
Many operators instinctively push harder when progress slows, but excessive pressure can overload the tool and generate additional heat.
Instead, apply firm but controlled pressure and allow the cutting edges to do the work. The drill should be producing consistent chips rather than rubbing against the material.
If chips stop forming and the tool begins squealing excessively, review your speed, pressure, and lubrication before continuing.
5. Use Step-Up Drilling for Larger Holes
When producing larger holes, progressively increasing drill bit size can reduce strain on both the tool and operator.
For example:
- Start with a smaller pilot hole.
- Enlarge using an intermediate size.
- Finish with the final diameter.
This staged approach improves accuracy and reduces the torque required during each drilling operation.
6. Take Care When Using TCT Hole Saws
For larger diameter holes, carbide-tipped (TCT) hole saws provide an efficient solution.
When using a hole saw:
Start with the Pilot Drill
Use the pilot drill to establish the hole location.
Run at moderate speed and pay attention as the pilot drill approaches breakthrough. Many pilot drills feature a stepped design that provides feedback when the point is about to exit the material.
As breakthrough approaches:
- Reduce pressure
- Ease off the trigger slightly
- Avoid forcing the cutter into the material
This helps prevent impact damage to the hole saw teeth.
Switch to Low Speed for the Main Cut
Once the pilot hole is complete, switch to the low-speed setting and keep the cutter running at a controlled pace.
Allow the carbide teeth to cut steadily rather than forcing them through the material.
Keep the Cutter Flat
When starting the cut, ensure the hole saw is seated squarely against the workpiece.
Starting at an angle can cause uneven tooth loading and increase the risk of snagging.
7. Support Larger Drills Properly
As cutter size increases, so do torque forces.
Always use the auxiliary handle supplied with the drill when operating larger hole saws or cutters. This improves control and reduces the risk of injury if the tool snags unexpectedly.
Keeping the drill close to your body also helps you maintain stability and control throughout the cut.
8. Watch the Swarf
One of the easiest ways to judge whether your drilling parameters are correct is by looking at the chips being produced.
Good drilling conditions typically produce consistent, well-formed swarf.
If you see:
- Blue or burnt chips
- Excessive smoke
- High-pitched squealing
- Little or no chip formation
You may be running too fast, using insufficient lubrication, or applying incorrect pressure.
The swarf often tells you more about drilling performance than the sound of the drill itself.
The Key to Successful Stainless Steel Drilling
When drilling stainless steel, success comes down to three fundamentals:
Slow Speed
Keep RPMs under control to reduce heat generation.
Adequate Lubrication
Apply cutting fluid frequently throughout the cut.
Controlled Feed Pressure
Use firm, consistent pressure without forcing the tool.
By following these principles, you'll achieve cleaner holes, extend tool life, and reduce the frustration often associated with drilling stainless steel.
Whether you're using cobalt drill bits for smaller holes or TCT hole saws for larger diameters, a slower, well-lubricated approach will consistently deliver the best results.