Drilling hardened steel is a difficult task that requires specialized equipment and techniques. The hardness and toughness of the material make it challenging to drill through without damaging the drill bit or producing poor-quality holes. However, with proper maintenance of the drill bit, you can increase its lifespan and ensure the quality of the holes drilled through hardened steel.
This article will discuss the techniques and tips for maintaining drill bit quality when drilling through hardened steel.
Achieving Perfect Results: Maintaining Drill Bit Quality When Drilling Hardened Steel
Choose the right drill bit
Selecting the correct drill bit is the first and most crucial step in ensuring the quality of holes drilled through hardened steel. Using a low-quality or incorrect drill bit can lead to premature wear and breakage.
The recommended drill bit for drilling hardened steel is a cobalt drill bit. These drill bits are made of a high-speed steel alloy with added cobalt content, which increases their hardness, strength, and heat resistance. They also have a thicker web and a shorter flute length, which reduces the possibility of the drill bit bending or breaking.
Use lubrication
Lubrication is essential when drilling through hardened steel. It reduces friction, which generates heat that can damage the drill bit and the material being drilled. Lubrication also helps to flush out chips and debris from the hole, reducing the possibility of clogging and binding.
Several lubricants are available when drilling through hardened steel, including cutting, mineral, and synthetic oil. Cutting oil is the most commonly used lubricant for drilling hardened steel. It has a high viscosity and provides excellent lubrication and cooling. Mineral oil is less viscous and less expensive than cutting oil, while synthetic oil is more expensive but provides better lubrication and cooling.
Control the drilling speed.
The drilling speed also affects the quality of the holes drilled through hardened steel. The drill bit’s rotational speed determines how fast it cuts through the material. A slow drilling speed can cause excessive heat buildup, leading to premature wear and damage to the drill bit. On the other hand, a fast drilling speed can cause the drill bit to become dull quickly.
The recommended drilling speed for drilling through hardened steel is between 500 and 1000 RPM. However, the optimal speed depends on several factors, including the diameter of the drill bit, the material being drilled, and the lubricant used. Adjusting the drilling speed accordingly is essential to ensure the best quality holes.
Maintain proper pressure and feed rate
Maintaining the correct pressure and feed rate when drilling through hardened steel is also crucial to the quality of the holes drilled. Applying too much pressure can cause the drill bit to break, while too little pressure can result in poor-quality holes.
The recommended pressure for drilling through hardened steel is between 60 and 80 pounds per square inch (psi). The feed rate is when the drill bit penetrates the material being drilled. A slow feed rate can cause the drill bit to rub against the material, leading to excessive heat buildup and dulling of the drill bit. A fast feed rate can cause the drill bit to break or produce poor-quality holes.
The recommended feed rate for drilling through hardened steel is between 0.001 and 0.003 inches per revolution (ipr). However, the optimal feed rate depends on several factors, including the diameter of the drill bit, the material being drilled, and the lubricant used.
Inspect and sharpen the drill bit regularly
Regular inspection and sharpening of the drill bit are essential to maintaining its quality and extending its lifespan. The drill bit should be inspected after each use for signs of wear, such as dullness, chipping, or cracking. A dull or damaged drill bit can produce poor-quality holes or even break while in use.
Sharpening the drill bit involves regrinding the cutting edge to restore its sharpness. A drill bit can be sharpened using a bench grinder or specialized tool. It is essential to maintain the correct angle and shape of the cutting edge when sharpening the drill bit.
Sharpening the drill bit after every 10 to 15 holes drilled through hardened steel is recommended. However, the frequency of sharpening depends on several factors, including the hardness of the material being drilled, the quality of the drill bit, and the drilling conditions.
Store the drill bit properly.
Proper drill bit storage is essential to prevent damage and maintain its quality. The drill bit should be stored in a dry and cool place, away from moisture and extreme temperatures. It should also be stored separately from other tools and materials to prevent damage from contact.
The drill bit should be stored in a protective case or holder to prevent it from becoming dull or damaged. The case or holder should be labeled with the drill bit size and type for easy identification.
Conclusion
Drilling through hardened steel requires specialized equipment and techniques to ensure the quality of the holes drilled and the lifespan of the drill bit. By choosing the right drill bit, using lubrication, controlling the drilling speed, maintaining proper pressure and feed rate, inspecting and sharpening the drill bit regularly, and storing it correctly, you can preserve the quality of the drill bit and produce high-quality holes in hardened steel.
It is important to note that drilling through hardened steel can be a hazardous process, and proper safety precautions should be taken, including using personal protective equipment, such as eye protection and gloves.
