Which Drill Bits Are Suitable for Hard Metal?
If you want to enlarge a hole in steel or drill iron with precision you can't go wrong: you need drill bits for hard metal. It's not a random choice, you have the need to identify the best products and built with the appropriate techniques. But also with ideal materials. Several elements come into play that influence the toughness and hardness of these drilling tools.
Because they can be mounted on manual or column drills, working continuously for several hours. Certainly, if you want to work on the most resistant metals you can't settle for a standard drill bit: you might manage to drill but the result is mediocre. We recommend the essential points to observe to choose the best drill bits for hard metal (even very hard metal).
Materials of drill bits for hard metals
Starting point for choosing the best drill bits for drilling steel, iron and other difficult to work metals: the composition of the material with which the blade and the tool profile were built. The starting point is clear: HSS. A drill bit suitable for drilling hard materials must be at least made of high speed steel, that is, super-fast steel. The characteristic of this composition: the presence of cobalt which allows operating at high temperatures, typical of drilling in hard metal.
All this without reducing cutting capacity. Obviously the HSS acronym is reductive, there are several combinations useful for obtaining high-quality drill bits dedicated to drilling hard metals. HSS-Co (with 5% cobalt) is a good starting point that satisfies most applications. But there are others. Like HSS-E (or HSSE) suitable for stainless and hardened steel.
| Steel type | ISO/Germany/USA | Code | Application |
|---|---|---|---|
| HSS | S 6-5-2 (DMo5/M2) | 1.3343 | Tools for general applications. |
| HSS-Co | S6-5-2-5 (EMo5Co5/M35) | 1.3243 | High heat resistance, suitable for roughing. |
| HSS-E | S6-5-3 (EMo5V3/M3) | 1.3344 | Wear resistance and cutting edge stability. |
| HSS-E M 42 | S2-10-1-8 (M42) | 1.3247 | Higher heat resistance and hardness. |
| P/M HSS-E | S 6-5-3-9 | 1.3207 | Hardness, heat resistance and stability. |
What is the TiN coating for?
You know drill bits for metal with TiN coating. What is it about? With this term we mean a coating treatment with titanium nitride - a ceramic material particularly hard composed of nitrogen and titanium - of the drill bit.
This leads to the least possible friction and minimal wear, all to the advantage of tool efficiency and durability. The TiN coating of a drill bit is recognizable thanks to the gold color that the tool acquires.
This is not the only available coating. For example, drill bits designed for drilling cast iron have a treatment known as nitriding that hardens the surface, while vaporization is an excellent solution to reduce the oxidation problem.
Structure and shape of the drill bit for hard metals
You must remember that to drill hard and very hard metals, like stainless or hardened steel, you need a drill bit HSS in titanium or cobalt, this is the best solution. The shape must be the typical one for drilling iron which provides a very precise line. To give you an idea, here is an example of a drill bit for hard metal and steel from Krino. Differences compared to solutions for drilling wood?
Is a very pointed forward section missing? While for stone? There are no typical wings. Here we have a very precise pyramidal shape. For example, the base solution offers an angle of 118° and is perfect for standard metals and steel.
Advanced solutions in terms of metal drilling propose an inclination of about 130° for drilling hard and very hard metals. Especially when combined with certain materials. This is the case of the Krino HSS-Co 8% drill bit, that is with a percentage of cobalt and molybdenum above 5%, perfect for high alloy steels and stainless steel, super resistant and drilled at high temperatures.
Which DIN to choose for drill bits suitable for hard metals?
The DIN concept concerns the shape of the drill bit. For example, the Krino DIN 1897 and DIN 6539 are extra-short bits with a depth of less than 3xD (three times the diameter of the bit) while for deep drilling there are the DIN 340 and 338 of Krino.
The 01305, specifically, is a drill bit with excellent resistance to thermal stresses, for drilling hardened, tempering steels and hot and cold working steels. The characteristic of this drill bit? A super-resistant material HSS-CO 5% with cross-sharpening and helix designed for deep drilling. Special mention must be made of the Speedmaster drill bit.
What makes the difference in this case? Why do we mention it with pleasure? Simply, it works well. The drill bit in question has 3 non-slip flats on the shank spaced 120° apart. This way you can get maximum power transmission from the chuck.
Everything interesting, isn't it? But the benefits don't end there. Also you have self-centering micro-tip, double pair of cutting edges to increase the efficiency of this very hard metal drill bit and chip breaker to avoid the formation of scrap material.
