4 features to identify a good metal drill at first glance

How can I recognize a good metal drill at first glance?

Yes, this question is often asked and is especially important when making a purchase decision in person. We'd like to dispel two misconceptions right away: price is not the sole criterion for assessing quality, and even certification marks like VPA or TÜV say little about a product's performance. Drills are mass-produced products. Testing institutes can only test sample drills. Whether mass production meets the criteria is another matter.

It's best if you inspect the product yourself and first pay attention to the following...

1. Labeling of the twist drills

Is the labeling easy to read? Is there any indication of the distributor's identification or codes for tracking? Some drill bit manufacturers mark the drill bits with codes to enable traceability and, in the event of a problem, to determine which production facility the product was manufactured at and when. This is a clear indication that quality assurance is taken seriously and a corresponding strategy is being pursued.

2. Processing of twist drills

Then look at the workmanship, especially the drill bit tip. The drill bit tip should always be symmetrical, and the cutting edge should have a noticeable relief. This means the main cutting edge should slope backwards, opposite the direction of rotation. If this isn't the case, the drill bit won't cut, but rather scrape.

3. Spiral groove on the drill

You can easily tell whether a drill bit is rolled or ground by the spiral flute's exit. If the exit is more rounded, it's rolled. Ground drill bits are more expensive because the manufacturing process takes longer. They are generally more precise and have a higher concentricity. Rolled drill bits have a better microstructure and are more robust in use.

4. Material of the twist drill

If you have any doubts about the quality of the material, you can use a simple trick to determine whether it's high-speed steel or tool steel: Hold the drill against a grinding wheel and watch the sparks fly. You'll quickly notice the differences. Try it out with different materials!

Sometimes drill bits are not hardened, are not hardened sufficiently, or are not hardened correctly. Here, too, there's a simple trick to solve the problem: take a file and file a notch into the drill bit. If this is easy to do, the product is not hardened or not hardened sufficiently. If the drill bit breaks very easily, then it's too hard. This happens if the drill bit hasn't been tempered or tempered sufficiently often after hardening.