Best Drill Bits for Stainless Steel – Types, Tips & Techniques

Drilling stainless steel is a challenge that requires the right tools, materials, and techniques. Stainless steel’s high tensile strength and hardness make it prone to work hardening and overheating if drilled with improper bits or methods. Choosing the correct drill bit not only ensures precision but also prolongs tool life and prevents damage to your workpiece.

Understanding Stainless Steel and Drilling Challenges

Stainless steel is a corrosion-resistant alloy primarily made of iron, chromium, and sometimes nickel. Its strength and toughness vary depending on the grade, but even softer grades resist cutting and generate high heat when drilled. Common challenges include:

Work hardening: Stainless steel hardens at the cutting edge when drilled too slowly or with a dull bit.

Overheating: Excessive heat can ruin the drill bit’s temper and lead to poor performance.

Burr formation: Poor bit selection or speed may create rough edges.

Because of these factors, choosing the right drill bit is critical.

Types of Drill Bits for Stainless Steel

1. Cobalt Drill Bits (HSS-Co)

Best for: All grades of stainless steel

Material: High-Speed Steel with 5–8% cobalt

Advantages:

Retains hardness at high temperatures

Excellent wear resistance

Can drill hard stainless steel without dulling quickly

Tips:

Use slower speeds compared to soft metals

Apply cutting oil to reduce heat and friction

2. Titanium-Coated Drill Bits

Best for: Light to medium stainless steel applications

Material: HSS with titanium nitride (TiN) coating

Advantages:

Coating reduces friction

Lasts longer than standard HSS bits

Cuts efficiently in thin stainless sheets

Tips:

Avoid re-sharpening coated bits often, as this removes the coating

Use moderate feed pressure to prevent overheating

3. Carbide Drill Bits

Best for: Harder stainless steel grades or industrial applications

Material: Tungsten carbide

Advantages:

Extremely hard and wear-resistant

Maintains sharpness at high temperatures

Suitable for CNC or heavy-duty drilling

Tips:

Brittle, so avoid lateral pressure

Ideal for high-speed applications with coolant

4. Uncoated High-Speed Steel (HSS)

Best for: Occasional light stainless steel drilling
Advantages:

Affordable and readily available

Can be sharpened multiple times

Works well with proper lubrication

Tips:

Keep drill bit cool with cutting oil

Start slowly to prevent work hardening

Drilling Techniques for Stainless Steel

Use a Pilot Hole: Start with a small bit (e.g., 1/8") before using a larger bit to reduce stress on the material.

Slow Speeds: Stainless steel requires slower RPM to prevent heat buildup.

Steady Pressure: Apply firm but consistent pressure; don’t force the drill.

Lubrication: Cutting oil or specialized drilling fluids prolong tool life and improve performance.

Peck Drilling: For thicker sheets, periodically retract the bit to remove chips and reduce heat.

Common Mistakes to Avoid

Using high-speed steel bits at full speed

Drilling without lubricant

Applying excessive pressure, causing bit breakage or work hardening

Ignoring pilot holes for large diameter drills

Conclusion

The ideal drill bit for stainless steel depends on the application and the steel grade. Cobalt bits are the gold standard for most situations, titanium-coated bits offer longevity for moderate use, and carbide bits excel in industrial or hard-grade drilling. Coupled with proper speed, lubrication, and technique, these bits ensure precise, clean holes without damaging your workpiece or tools.