HSS vs Cobalt Drill Bits: Which Is Best for Steel?

When it comes to drilling through steel, using the right metal drill bit is critical. Two of the most commonly used options for this purpose are HSS (High-Speed Steel) and Cobalt drill bits. While both are capable of cutting through metal, understanding their differences can help you choose the most suitable tool for your specific job. 

At Speedy Fixings, we stock a range of steel cutting drill bits designed for accuracy, durability, and professional performance. So, which should you choose – HSS or Cobalt? 

What Are HSS Drill Bits? 

HSS (High-Speed Steel) drill bits are made from a strong alloy that allows for high-speed drilling. These are versatile, affordable, and suitable for cutting through wood, plastic, and soft metals, including mild steel. 

Pros: 

  • Cost-effective and widely available. 
  • Good for general-purpose use. 
  • Can handle moderate temperatures without losing hardness. 

Best For: 

  • Light-duty steel drilling. 
  • DIY tasks. 
  • Mixed-material projects where steel is not the primary focus. 

 

What Are Cobalt Drill Bits? 

Cobalt drill bits are made from a cobalt alloy (typically 5–8% cobalt), which gives them greater hardness and heat resistance compared to standard HSS bits. They’re especially suited for drilling into harder metals, such as stainless steel, cast iron, and high-tensile steel. 

Pros: 

  • Extremely durable and long-lasting. 
  • High resistance to heat, making them suitable for high-speed or repetitive drilling. 
  • Better performance on hard and abrasive materials. 

Best For: 

  • Stainless steel and hardened metals. 
  • Professional or industrial metalwork. 
  • Frequent or heavy-duty steel drilling jobs. 
  • Faster drilling with less down-time to change bits. 

 

Key Differences at a Glance 

Feature  HSS Drill Bits  Cobalt Drill Bits 
Material  High-speed steel alloy  Cobalt-alloy steel (5–8% cobalt) 
Heat Resistance  Moderate  High 
Durability  Good for general use  Excellent for repeated steel drilling 
Cost  More affordable  Higher upfront cost but longer lasting 
Best Use  Mild steel, wood, plastics  Stainless steel, hardened metals 

 

Which Should You Choose? 

If you’re drilling through mild or structural steel occasionally or as part of a mixed-material project, HSS drill bits will do the job without breaking the bank. However, if you frequently work with tougher materials like stainless steel or cast iron, Cobalt drill bits are a more reliable and long-lasting choice, particularly in trade or industrial settings. 

 

Find the Right Drill Bits at Speedy Fixings 

Whether you need dependable HSS bits for everyday use or high-performance Cobalt bits for heavy-duty steelwork, Speedy Fixings has you covered. We stock a wide range of steel cutting drill bits in various diameters and specifications to suit every project and budget. 

Browse our full selection of steel cutting bits and enjoy fast UK delivery on every order.