Drilling into hard metals, such as stainless steel, cast iron, hardened steel and titanium alloys, requires the right tools. Ordinary drill bits wear out quickly, overheat or fail to cut altogether. To achieve clean holes and prolong tool life, choosing the correct drill bit is essential.
This guide breaks down the best drill bits for hard metal applications, explains key differences between materials and shares practical tips to maximize performance.
Why Hard Metals Require Specialized Drill Bits
Hard metals have high tensile strength and density, which create significant resistance during drilling.
Without a suitable bit, you may experience:
- Excessive heat buildup
- Rapid edge dulling
- Bit breakage
- Rough or uneven holes
Using a high-quality drill bit designed for metal cutting ensures better precision, less heat and improved safety.
1. Cobalt Drill Bits: Best Overall for Hard Metals
Cobalt drill bits are the most popular choice for drilling tough metals. Made from alloyed steel containing 5–8% cobalt, they offer:
- Excellent heat resistance
- High durability
- Ability to maintain sharpness under heavy load
They are especially effective for stainless steel and hardened steel.
2. Carbide Drill Bits: Best for Industrial-Grade Hardness
Carbide drill bits are significantly harder than cobalt. They are ideal for:
- Cast iron
- High-carbon steel
- Abrasive alloys
- Repetitive industrial drilling
While more brittle than cobalt, carbide bits offer unmatched cutting power and wear resistance.
3. Titanium-Coated Drill Bits: Best for Occasional Use
Titanium coatings such as TiN, TiCN or TiAlN reduce friction and increase durability. They are suitable for light to moderate drilling of hard metals.
Benefits include:
- Smooth drilling
- Reduced heat
- Longer life compared to standard HSS
However, once the coating wears off, performance drops noticeably.
4. HSS Drill Bits (High-Speed Steel): Budget but Limited
Standard HSS drill bits are not ideal for very hard metals, but they can handle:
- Mild steel
- Aluminum
- Copper
They are a budget option but not recommended for stainless steel or hardened alloys unless coated.
You may include HSS sets as an upsell option for general-purpose users.
Key Features to Consider When Choosing Drill Bits for Hard Metal
Material Composition
Cobalt and carbide offer the best results for high-hardness materials.
Point Angle
- 135° split-point: Best for metal; reduces walking and improves positioning.
- 118° angle: More common in general-purpose bits.
Coating
Look for coatings such as:
- Titanium Nitride (TiN)
- Titanium Carbonitride (TiCN)
- Black oxide (for lubrication)
Shank Design
Hex-shank bits improve grip, especially for power drills and impact drivers.
Bit Length
Shorter bits resist bending and are better for hard metals. Use jobber-length or stubby bits where possible.
Tips for Drilling Hard Metal Efficiently
Even the best drill bit performs poorly without proper technique. Keep these tips in mind:
1. Use Cutting Oil
Reduces heat and prolongs bit life.
2. Drill at a Low Speed
Hard metals require slower RPMs to prevent overheating.
3. Apply Steady, Moderate Pressure
Too much force can break the bit; too little causes excessive heat.
4. Start with a Pilot Hole
A small pilot hole improves accuracy and reduces cutting load.
5. Keep the Bit Cool
Periodically withdraw the bit to remove chips and allow cooling.
Best Uses for Each Drill Bit Type
| Drill Bit Type | Best For | Durability | Cost |
| Cobalt | Stainless steel, hardened steel | High | Medium |
| Carbide | Cast iron, industrial alloys | Very High | High |
| Titanium-Coated | Occasional metal drilling | Medium | Medium |
| HSS | Soft metals, general use | Low-Medium | Low |
Recommendation
If you need the strongest option for consistent drilling in very hard metals, carbide drill bits are your best choice. For most workshops and industrial users, cobalt drill bits offer the best balance of performance and cost. Titanium-coated bits are suitable for lighter tasks, while HSS bits are best reserved for soft metals.
