Please note: the articles have been translated automatically.
The tool, which is in direct contact with the workpiece to be machined, is often more responsible for a good quality of execution than the machine tool itself. However, if you don’t just want to buy the next best drill, you quickly start pondering what to do with these now exist and what do all the abbreviations mean. Here is a list of different tool materials and their common abbreviations:
| HSS | stands for high-speed steel. HSS is therefore only the designation of the base material and not of further processing (like HSS-R, HSS-G). Temperature resistance up to 600 °C (depending on alloy composition). Common alloying elements: iron, tungsten, vanadium, molybdenum, cobalt and chromium. Depending on the temperatures at which vacuum hardening takes place, different degrees of hardness are possible (56 to 66 Rockwell). Author’s note: if a drill is only labeled HSS, I would assume it is an HSS-R drill. |
| HSS-R | roll-rolled high-speed steel. Standard quality of HSS tools. Due to the rolling (similar to kneading dough), the alloy components are well distributed and are therefore very break-resistant (suitable for robust use and forgive application errors), but they are somewhat less precise than HSS-G tools. Suitable for: steel, cast iron, brass, etc. |
| HSS-G | ground high-speed steel. During production, the tool is milled from the material and then hardened. The spiral and cutting edges of drills are ground (HSS-G drills can be recognized by the metallically bright spiral). Due to the usual split point at the tip, these are particularly well suited for pre-drilling. Compared to HSS-R drills, HSS-G drills are more precise and have a longer service life. Suitable for: steel, cast iron, brass, etc. |
| HSS-E or HSS-E Co / HSS Co | HSS-E tools differ from HSS-G tools in that they have a higher cobalt content of 5-8%, giving them greater strength and higher heat resistance. Depending on the manufacturer, different abbreviations are used here. Suitable for: like HSS-G and HSS-R, but also for tough metals like stainless steel |
| HSS-TiN | HSS-G tools coated with titanium. Due to the higher surface hardness and lower roughness, the sticking of the chip is prevented and the machining is more precise. Suitable for: like HSS-E, i.e. also for stainless steel Author’s Note: Since drill bits and tools are reground from time to time, I prefer an uncoated tool as the coating is removed from the ground surface. In other words, I prefer HSS-E drills (or commonly cobalt drills) to titanium-coated drills. |
| HM | Carbide, mainly made of tungsten carbide, from which the tool is made by powder metallurgical sintering. This material is typically only used for cutter blades for milling cutters or lathe tools. If the entire tool is made of HM, one also speaks of solid carbide (VHM). Solid carbide tools are significantly more expensive. Due to the temperature resistance of up to 900 °C, higher speeds and processing speeds are possible. However, they have low fracture resistance and low resistance to temperature changes. With hard metal, degrees of hardness from 85 to 95 Rockwell are possible. They are used where particularly hard materials are processed or where very precise processing is required. Suitable for: like HSS-E, i.e. also for stainless steel and for processing metals with high hardness |
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