Three Drilling Tips for Automotive Technicians

Automotive and diesel technicians today need a wide variety of skills to get cars, trucks and fleets back on the road and running at peak performance. One skillset that takes constant refinement is operating a drill. This skill is most commonly used when a technician finds himself behind a broken bolt that needs to be extracted. Whether by hand or on a press, understanding the anatomy of a drill and knowing best practices will save you time and money over and over again as a technician. Here are three drilling tips that we recommend every technician takes the time to understand and develop.

Don’t max out your RPMs! This is not a race. The number one factor that is going to wear out or break your drill bits is SPEED. A general rule of thumb is the harder the metal, the slower the drill speed. The hardness of the tooling you are drilling with will also impact the recommended cutting speed. The harder the drill, the faster the cutting speed.
Always follow the instructions that are included with your tooling – the last thing you want to do is “work harden” metal you are attempting to drill through. Work hardening is the result of exposing your cutting surface to friction and thus heat, resulting in the metal hardening even further and making it more difficult to drill through.

2. Pressure
When drilling through hardened metals (or any material), thinking about the physics of the process will pay dividends. You’re using a hardened, sharpened bit to drill through another material. Let it do its job, which is to cut the hardened metal, then extract it via the flutes on the tooling. Apply pressure, then pull it back out, clearing the cutting area of shavings which can build up, creating torque and pressure which will cause your tooling to break and dull.
Heat and friction are another factor that needs to be considered while drilling. By applying a drill lube or cutting fluid, you can reduce friction and heat that your tooling is exposed to while cutting through harder metals like steel. A little bit goes a long way! In addition to cooling down the drill job, cutting fluid will allow for a cleaner cut and allow your harder (and more expensive) tooling to last much longer.

3. Drill Bit Quality
Tooling isn’t created equally. There are two main features which will determine the quality of a drill bit. The material and the design.
Drill bits can be made of high-speed steel, cobalt or carbide. Each more expensive to produce than the last – yet each also capable of cutting harder materials than the last.
The design of the drill bit is equally important to the quality. One of the main design variants in drill bits is the drill point angle. The industry standard is between a 118-degree and 135-degree drill point angle. The 118-degree has a more aggressive cutting edge, whereas the 135-degree isn’t as steep, slowing down the drilling process. When cutting through harder materials, a 135-degree drill point angle is going to be necessary to cut through the hardened metal before dulling or breaking your tooling.

Technicians are under the gun to get trucks out of the service this profession are looking for more ways to become more productive. ProMAXX Tool's main objective is to provide these technicians with tools and knowledge that make them more productive and confident professionals that can tackle any job that comes their way. For more information on the tooling we suggest for drilling through hardened metal, visit or give our experts a call at 724-941-0941.

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