Drilling applications require careful consideration of material, production volume, and machine setup to ensure optimal hole quality, tool life, and cost. Harvey Performance Company offers drills in three primary substrates: carbide, cobalt, and high-speed steel (HSS). This guide breaks down the differences between the drilling substrate options and helps you choose the right tool for your specific application.

Solid Carbide Drills

Advantages of Carbide Drills

1. Extreme Hardness and Wear Resistance
   • Carbide drills maintain sharp cutting edges longer than HSS or cobalt, even in abrasive materials. This reduces tool changes and helps to maintain consistent hole quality.
2. High Heat Tolerance
   • Carbide can withstand cutting temperatures above 2,100°F (1,150°C), allowing higher speeds and feeds for faster material removal and shorter cycle times.
3. Precision Machining
   • Carbide maintains tight tolerances and excellent surface finish in hard steels, tool steels, ceramics, composites, and high-temperature alloys, making it ideal for precise, high-performance applications.
4. Long-term Cost Efficiency
   • Although the initial cost is higher, carbide’s longer tool life reduces frequent tool changes, lowering overall costs in high-volume production.

Drawbacks of Carbide as a Drill Substrate

1. Brittle Nature
   • Carbide is more prone to chipping or breaking if the machine setup is not rigid, feed rates are too aggressive, or vibration is present.
2. Regrinding Requirements
   • Carbide usually requires CNC grinding equipment for precise sharpening, unlike HSS, which can often be reground using conventional machines.
3. Initial Investment
   • Carbide has a higher upfront cost, which may not be justified for use in short runs or soft materials, where less expensive HSS or cobalt drills can provide adequate performance.

What are the Ideal Applications for Carbide Drills?

Carbide drills excel in:

• Large production runs requiring consistent tool life
• Hard materials above 45 HRC, such as tool steels and high-temperature alloys
• Applications requiring high-speed cutting and maximum material removal
• Situations demanding precise hole tolerances and surface finish

Example: Valor Holemaking High Performance Carbide Drills are engineered to provide unmatched precision and repeatability in difficult-to-machine materials. Material-specific geometries and coolant-through designs improve heat management and tool life in demanding applications.

High Speed Steel (HSS) Drills

Advantages of HSS Drills

1. Tough and Durable
   • High Speed Steel is the least brittle of the three materials, reducing the risk of breakage during less rigid setups.
2. Easier to Regrind
   • HSS Drills can be sharpened and reconditioned using conventional grinding equipment, which reduces shop complexity and cost.
3. Cost-Effective
   • The lower cost-per-tool makes HSS ideal for small jobs or low-volume production where long-term tool life is less critical.
4. Versatile for Soft Materials
   • HSS performs well in most non-ferrous metals providing reliable results for general-purpose machining without the higher cost of harder substrates.

Drawbacks of High Speed Steel Drills

1. Limited Heat Tolerance
   • High Speed Steel Drills can only handle cutting temperatures up to 1,100°F (600°C), restricting cutting speeds and material removal rates.
2. Shorter Tool Life
   • HSS Edges dull faster than cobalt or carbide, requiring more frequent replacement, affecting productivity.
3. Not Ideal for Very Hard Materials
   • High speed steel tools cannot reliably machine steels above 45 HRC or high-temperature alloys.

What are the Ideal Applications for HSS Drills?

HSS drills are ideal for:

• Soft materials like aluminum, brass, and other non-ferrous metals
• Small production runs or one-off jobs where tool life is less critical
• Shops without CNC grinding capability
• Situations where cost and ease of regrind outweigh long-term performance

Example: Titan USA High Speed Steel Drills provide reliable performance for general-purpose machining and softer materials, offering versatility for low- to medium-volume operations.

Cobalt Drills

Advantages to Cobalt Drilling

1. Intermediate Hardness
   • Cobalt is harder than HSS but less brittle than carbide, providing a balance of toughness and wear resistance.
2. Higher Heat Resistance
   • Cutting temperatures up to 1,580–1,616°F (860–880°C) enable faster speeds and feeds than HSS.
3. Moderate Cost
   • Cobalt drills offer longer tool life than HSS without the higher upfront cost of carbide.
4. Capability for Harder Materials
   • Can machine steels up to 58 HRC, handling materials that high speed steel struggles with, while remaining more forgiving than carbide.

Cobalt Drill Disadvantages

1. Less Wear-Resistant than Carbide
   • While cobalt drills are harder than HSS, they are still not as wear-resistant as carbide. In extremely abrasive materials, cobalt drills will wear much faster than solid carbide, which can increase tool changes and impact long-term cost in high-production runs.
2. Slightly More Brittle than HSS
   • Cobalt is harder than HSS, making it more prone to chipping or breakage. Regrinding may require careful handling or CNC equipment to maintain geometry.
3. Not Suitable for Extreme High-Temperature Alloys or Very Hard Materials
   • Cobalt cannot maintain performance in very hard steels or high-temperature alloys. Carbide is needed for materials above 60 HRC or extreme heat applications.

What Applications are Ideal for Cobalt Drills?

Cobalt drills work well for:

• Medium-volume jobs with harder materials
• Applications requiring more speed and heat tolerance than HSS
• Shops seeking a balance of cost, tool life, and performance

Example: Titan USA Cobalt Drills are a solid choice for harder-to-machine materials that do not require carbide, providing longevity and moderate speed capabilities.

What Factors Influence What Drill Substrate to Choose?

Every drilling job is unique, and the optimal drill substrate depends on your specific requirements. Key considerations include:

• Material Hardness
• Production Volume and Job Size
• Machine Rigidity
• Budget
• Regrinding Capabilities
• Desired Cutting Speed and Material Removal Rate

No drill fits every job, and these factors are intended as a guide to help machinists choose the right substrate to improve efficiency, precision, and cost-effectiveness.