How To Drill Hardened Steel: Conquer Tough Materials

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Drilling hardened steel can be daunting, as it requires specific techniques and tools to penetrate its tough surface. Whether you’re a professional or a DIY enthusiast, understanding the best practices for drilling hardened steel is essential to achieve accurate and satisfactory results. This article will explore how to drill hardened steel and various aspects of drilling hardened steel, including the tools and equipment needed, drilling techniques, safety precautions, troubleshooting tips, and more. So, let’s dive in and discover the secrets to successfully drilling hardened steel.

How To Drill Hardened Steel

1. Understanding Hardened Steel

I. What is hardened steel?

Hardened steel is a type of steel that has been subjected to heat treatment processes, such as quenching and tempering, to increase its hardness and durability. This makes it suitable for applications requiring wear resistance, abrasion, and impact. However, the same characteristics that make hardened steel desirable make it challenging to drill.

II. Properties and challenges of hardened steel

Hardened steel possesses high hardness, typically measuring above 40 on the Rockwell C hardness scale. It is characterized by its toughness, strength, and resistance to deformation. Several challenges arise when attempting to drill hardened steel, including extreme hardness, reduced drill bit life, heat generation, and chip evacuation difficulties. Overcoming these challenges requires specialized techniques and tools.

2. Tools and Equipment for Drilling Hardened Steel

I. Types of drills suitable for hardened steel

When drilling hardened steel, not all drills are created equal. It would be best to have a drill that delivers sufficient power and torque to penetrate the tough surface. High-speed steel (HSS), cobalt, and carbide drills are commonly used for this purpose. Cobalt drills and carbide drills are particularly effective due to their hardness and heat resistance.

II. Drill bit materials for drilling hardened steel

Drill bits for hardened steel are made from materials that can withstand the hardness and heat generated during drilling. Cobalt drill bits, known for their high heat resistance, are an excellent choice. Carbide drill bits, with their superior hardness, are ideal for drilling through hardened steel. Diamond-coated drill bits are also available for even greater hardness and durability.

III. Choosing the right drill press for hardened steel

A drill press can provide stability and precision if you’re dealing with larger or more complex projects involving hardened steel. Look for a drill press with adjustable speed settings, a sturdy construction, and a strong motor. Ensure that it can accommodate the drill bits suitable for drilling hardened steel.

3. Preparing Hardened Steel for Drilling

Before drilling hardened steel, proper preparation is crucial to ensure accurate and clean holes.

I. Cleaning the surface

Begin by cleaning the surface of the hardened steel. Remove any dirt, rust, or debris that may hinder the drilling process. Use a degreaser or solvent to clean the surface thoroughly.

II. Marking the drilling points

To achieve precise drilling, mark the drilling points on the hardened steel. Use a center punch to create small indentations at the desired locations. These indentations serve as guides for the drill bit and help prevent it from wandering.

III. Center punching

After marking the drilling points, use a center punch to create a small depression at each marked location. This step provides a starting point for the drill bit and helps prevent it from slipping or wandering off course.

4, Drilling Techniques for Hardened Steel

When it comes to drilling hardened steel, adopting the right techniques is vital for success.

I. The slow and steady approach

Drilling hardened steel requires patience and a slow drilling speed. Apply steady pressure while maintaining a low rotational speed. Rushing the process or using excessive force can cause the drill bit to overheat or break.

II. Gradual pressure application

To prevent overheating and bit breakage, apply gradual pressure when drilling into hardened steel. Start with light pressure and gradually increase it as the drill bit penetrates the surface. This approach allows the drill bit’s cutting edges to remove material without excessive friction and heat buildup effectively.

III. Using cutting fluid or lubricants

Using cutting fluid or lubricants while drilling hardened steel can significantly improve performance and extend the life of the drill bit. Apply a suitable lubricant directly on the drilling point to reduce friction, cool the bit, and aid chip evacuation. Cutting fluids with high lubricities, such as mineral or sulfurized oil, are recommended for drilling hardened steel.

IV. Peck drilling method

The peck drilling method is particularly useful when drilling through hardened steel. It involves periodically withdrawing the drill bit slightly to clear chips and cool down the bit. Peck drilling helps prevent excessive heat buildup and chip packing, ensuring a smoother drilling process.

5. Recommended Drill Speed for Hardened Steel

The drill speed plays a crucial role in drilling hardened steel effectively. Operating the drill at the correct speed prevents overheating, bit dulling, and premature wear. Refer to the manufacturer’s guidelines to determine the appropriate drill speed for hardened steel. Generally, lower drill speeds are preferred to minimize heat buildup and preserve the integrity of the drill bit. Start with a slower speed and adjust as necessary based on the specific drill bit and steel hardness.

Drill Bit Selection for Hardened Steel

6. Drill Bit Selection for Hardened Steel

Choosing the right drill bit is essential for achieving clean and precise holes in hardened steel.

I. Cobalt drill bits

Cobalt drill bits are popular for drilling hardened steel due to their high heat resistance and toughness. They are made from cobalt alloys, which can withstand the extreme temperatures generated during drilling. Cobalt drill bits can retain their hardness even at high temperatures, making them suitable for prolonged drilling sessions.

II. Carbide drill bits

Carbide drill bits are another excellent option for drilling hardened steel. They are made from carbide and cobalt, producing superior hardness and heat resistance. Carbide drill bits can maintain their sharpness and hardness even when drilling through tough materials like hardened steel.

III. Diamond-coated drill bits

Diamond-coated drill bits offer exceptional hardness and durability for the most demanding drilling applications. The diamond coating increases the drill bit’s cutting ability and lifespan. Diamond-coated drill bits are particularly useful when drilling extremely hard or abrasive materials like hardened steel.

7. Safety Precautions when Drilling Hardened Steel

Drilling hardened steel requires careful attention to safety to prevent accidents and injuries. Follow these safety precautions for a secure drilling experience.

I. Personal protective equipment (PPE)

Always wear appropriate personal protective equipment, including safety goggles, a face shield, gloves, and ear protection. Hardened steel drilling can produce flying chips and noise, which can cause harm if not properly protected.

II. Eye protection

Wear safety goggles or a face shield to protect your eyes from flying debris and metal chips. Safety goggles with side shields offer additional protection against particles from different angles.

III. Secure the workpiece and clamp

Secure the workpiece firmly using clamps or a vise to prevent it from moving during drilling. This ensures stability and accuracy while minimizing the risk of accidents.

IV. Stable drilling surface

Ensure that the drilling surface is stable and secure. Use a sturdy workbench or surface that can withstand the forces exerted during drilling.

V. Safe handling of drill and accessories

Handle the drill and its accessories with care. Follow the manufacturer’s instructions for proper use and maintenance. Avoid using damaged or worn-out drill bits, as they can increase the risk of accidents and reduce drilling efficiency.

8. Overcoming Challenges when Drilling Hardened Steel

Drilling hardened steel presents several challenges. Here are some tips to overcome these challenges and achieve better drilling results.

I. Heat generation and control

Hardened steel drilling generates a significant amount of heat. Excessive heat can damage the drill bit and workpiece. Using cutting fluid or lubricants to cool the drilling point to control heat buildup. Peck drilling can also help dissipate heat and prevent excessive temperature rise.

II. Proper chip evacuation

Chip evacuation can be challenging when drilling hardened steel, as the chips tend to be tougher and more difficult to remove. Ensure that the drill bit flutes are clear and free from debris. Peck drilling, as mentioned earlier, aids in chip evacuation by periodically withdrawing the drill bit to clear the chips.

III. Avoiding bit breakage

Hardened steel is unforgiving when it comes to bit breakage. To avoid this:

  • Apply gradual pressure and avoid excessive force or aggressive drilling.
  • Use sharp and high-quality drill bits specifically designed for drilling hardened steel.
  • Replace dull or worn-out bits promptly to maintain optimal drilling performance.

9. Common Mistakes to Avoid when Drilling Hardened Steel

Drilling hardened steel requires precision and attention to detail. Avoid these common mistakes to achieve better drilling outcomes:

  • Using improper drill bits: Ensure that the drill bits you use are designed for drilling hardened steel. Using correct drill bits can result in a good performance and potential damage to the drill bit and workpiece.
  • Insufficient cooling and lubrication: Proper cooling and lubrication are essential for drilling hardened steel. Failing to use suitable cutting fluid or lubricants can lead to overheating, premature wear, and decreased drilling efficiency.
  • High drilling speed: Drilling hardened steel at high speeds can generate excessive heat and cause the drill bit to dull quickly. Keep the drilling speed low and adjust it based on the specific requirements of the steel and drill bit.
  • Inadequate chip evacuation: Hardened steel produces tougher chips that can hinder drilling. Ensure proper chip evacuation by using peck drilling and clearing the drill bit’s flutes regularly.
  • Lack of safety precautions: Drilling hardened steel involves inherent risks. Neglecting safety precautions, such as wearing appropriate PPE and securing the workpiece, can result in accidents, injuries, or damage to the equipment.

11. Lubricants and Coolants for Drilling Hardened Steel

Using the right lubricants and coolants while drilling hardened steel can enhance performance, extend tool life, and improve drilling outcomes.

I. Types of lubricants

Various lubricants can be used for drilling hardened steel, including mineral oil, sulfurized oil, cutting oils, or water-based cutting fluids. Each lubricant has advantages, such as reducing friction, dissipating heat, and aiding chip evacuation. Choose a lubricant suitable for your specific drilling needs.

II. Importance of cooling and lubrication

Cooling and lubrication play critical roles in drilling hardened steel. Cooling prevents excessive heat buildup, which can lead to drill bit dulling and premature wear. Lubrication reduces friction, facilitates chip evacuation, and prolongs the life of the drill bit.

III. Alternative Methods for Drilling Hardened Steel

While traditional drilling methods are commonly used for drilling hardened steel, alternative methods can be considered for specific applications.

IV. EDM (Electrical Discharge Machining)

EDM is a non-contact machining process that uses electrical discharges to erode the material. It is particularly suitable for drilling hardened steel with complex shapes or intricate details. EDM can provide precise results and is often used in specialized industries.

V. Laser drilling

Laser drilling utilizes high-powered lasers to create holes in materials, including hardened steel. The focused laser beam generates intense heat, which vaporizes and removes the material. Laser drilling offers high accuracy and can be used for small or delicate applications.

12. Troubleshooting Issues while Drilling Hardened Steel

Despite taking precautions, issues can arise while drilling hardened steel. Here are some common troubleshooting tips:

I. Dull drill bits

Dull drill bits can result in poor performance and difficulties in drilling hardened steel. To address this, sharpen or replace the dull bits with sharp, high-quality ones. Proper cooling and lubrication also help prevent premature dulling.

II. Excessive heat and burning

Excessive heat and burning during drilling can occur when the drill speed is too high, or cooling is inadequate. Reduce the drill speed and ensure proper cooling and lubrication to prevent overheating and burning.

III. Drilling at an angle

Drilling at an angle instead of perpendicular to the surface can result in misaligned or skewed holes. Ensure the drill is perpendicular to the hardened steel surface throughout the drilling process.

13. Recommended Drill Brands for Drilling Hardened Steel


Selecting dependable and top-notch drill brands is crucial for achieving the best outcomes when drilling hardened steel. For comprehensive reviews on the best drill bits suitable for drilling hardened steel, refer to the following resource: Best Drill Bit for Drilling Hardened Steel: Reviews.

14. Maintaining the Drill Bits and Equipment

Proper maintenance of drill bits is crucial for ensuring they perform optimally and last long. Here are some tips on how to maintain drill bits properly:

  • Keep the drill bits clean and free from debris, such as metal shavings or dirt. Wipe them down with a clean, dry cloth after each use.
  • Store the drill bits in a dry and cool place, away from moisture and humidity.
  • Use cutting oil or lubricant when drilling, especially in more rigid materials like hardened steel. This helps reduce heat and friction, which can cause premature wear and tear.
  • Sharpen the drill bits regularly using a sharpening tool or a professional sharpening service. Dull bits can cause damage to the material being drilled and put unnecessary stress on the drill itself.

The importance of maintaining drill bits and equipment must be balanced. Proper maintenance ensures that the equipment operates safely and efficiently, reduces the risk of accidents, and prolongs the lifespan of the tools.

15. FAQs

I. Can I use regular drill bits for drilling hardened steel?

Regular drill bits are not suitable for drilling hardened steel due to their lack of hardness and heat resistance. It is recommended to use specialized drill bits such as cobalt, carbide, or diamond-coated drill bits for drilling hardened steel.

II. How can I prevent drill bits from overheating when drilling hardened steel?

To prevent drill bits from overheating, use cutting fluid or lubricants specifically designed for drilling hardened steel. Apply the lubricant directly on the drilling point to reduce friction and dissipate heat. Additionally, adopt a slow and steady drilling approach, avoiding excessive force or high drill speeds.

III. Can I use a regular drill press for drilling hardened steel?

While a regular drill press can be used for drilling hardened steel, it is advisable to choose a drill press with adjustable speed settings, a sturdy construction, and a strong motor. Ensure the drill press is compatible with the drill bits suitable for drilling hardened steel.

IV. Are there alternative methods to drill hardened steel?

Alternatively, EDM (Electrical Discharge Machining) and laser drilling can be used for drilling hardened steel in specific applications. These methods offer precise results and can be particularly useful for complex shapes or delicate workpieces.

V. What should I do if my drill bit becomes dull while drilling hardened steel?

Suppose your drill bit becomes dull while drilling hardened steel; sharpening or replacing it with a sharp, high-quality drill bit is recommended. Dull drill bits can cause poor performance and difficulties in drilling. Ensure proper cooling, lubrication, and peck drilling techniques to maintain the sharpness of the drill bit and prolong its lifespan.

16. Conclusion

Drilling hardened steel requires specialized techniques, tools, and safety precautions. You can achieve accurate and clean holes in hardened steel by understanding the properties of hardened steel, selecting the right drill bits and lubricants, and adopting proper drilling techniques. Remember to prioritize safety, follow recommended guidelines, and troubleshoot any issues that may arise. With practice and attention to detail, you can master the art of drilling hardened steel and confidently tackle challenging projects.

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Hello. You've come to the right place if you want to learn more about power drills and how to make your home improvement projects go quicker and easier. I'm Jacob P., the founder and content writer of drill-guy.com. Anyone who needs assistance with a project or has a query about how something works (or doesn't) can count on me to share my expertise.