Mikron Tool SA Agno achieved a quantum leap in milling of stainless steel, titanium, chrome-cobalt alloys as well as the so called super alloys. The newly conceived small milling cutter improved by large margins the hitherto possible results in all aspects. Hence, new benchmarks apply immediately for cutting speeds, feeds, performance, tool life und surface quality. Hard to believe that these results are most dominant with the so called hard-to-machine materials.

Machining stainless steels can be a challenge. One factor is that the tool becomes extremely hot due to the poor heat conductivity of these materials and thus wears and can be damaged quickly. Also the factor efficiency and surface quality is an ongoing topic. With the CrazyMill Cool the Swiss tool specialist, Mikron Tool SA Agno, achieved a solid carbide Endmill with through coolant capability in the diameters from 0.3 mm to 4mm (0.02” to 0.15”), doing justice to the product’s somewhat wild name. Slot or pocket milling into solid material, and contour milling are its strengths. The tool combines roughing and finishing, promising at the same time high efficiency, long tool life and a much better surface quality.

That these promises can be kept and that the researchers of the Swiss Tool manufacturer once more talk about a “crazy” tool, for that several factors are decisive. First is the raw material, a newly developed micro granulate carbide,which fulfills the requirements of hardness as well as toughness. Obviously, the design of the tool with its cutting geometry, which is specific but not limited for the machining of stainless
steels, helps the tool to achieve its outstanding performance. A combination of different geometric characteristics lead to the targeted results. A robust cutting body, a radial relief and a very specific cutting edge preparation afford a very high cutting edge quality and stability. An important contribution for the tool life is also the coating, which is innovative and also very specific for hard to cut metals. With a extremely low friction coefficient and a reduced affinity with steel, build up at the cutting edges is avoided. Furthermore the coating has a high oxidation resistance and heat hardness. This helps to maintain the temperature in the green range and a “burning” of the cutting edges is avoided, which in turn is positive for tool life and surface quality.

The essence of innovation is however connected with the “cool” part of the tool’s name. Generally valid is: dry machining is not possible with stainless steels. Due to the bad heat conductivity of the material the tool would become extremely hot, the cutting edges burn out. The use of a coolant is a must. Mikron’s microcutter has three to four internal coolant channels which go through the shaft and bring such coolant along the diameter to the cutting edges. The result is a targeted and massive cooling effect where it’s needed: at the cutting edges and this in every machining position. Simultaneously chips are continuously flushed away from the milling area, where they would disrupt the perfect milling operation and could influence the surface quality negatively. In relation to the small diameters of the milling cutters the cooling
channels are rather large. The large volume of coolant created is highly efficient; the friction heat is substantially absorbed and removed by the coolant. It is also interesting that no special requirements are necessary for filtering and coolant pressure. Hence these tools can also be used profitably on conventional machines.

Up to date a. infeed of 0.1 – 0.2 x D was recommended to mill a channel into solid material. The CrazyMill Cool is able to achieved depths of 1 – 1.3 x D directly.Markus Schnyder, the responsible for Mikron Tool International points out, that one does not have to be a calculus genius to find out, that with up to five times faster cutting speed and a comparable feed the efficiency of the milling cutter is improved by a factor of 10 to 20! With this it is interesting that expressly the “difficult” materials are the ones where the difference regarding performance is most astounding. The cherry on the cake is, according to Mikron Tool,
the surface quality. Even though the cut goes into solid material, the CrazyMill Cool boasts Rz values which are 2 to 3 times better, than what can be expected from conventional cutters.

A complete inventory of standardized, small, milling cutters will be available for applications in industry segments such as watch-making, medicinal and surgical technologies etc. A first series of cylindrical, small cutters in diameter of 0.3mm to 4mm (0.02” to 0.16”) has been launched. A short version for maximum depths of 1.5 x D, a medium version for 3 x D and a long version for 5xD are available. All of these have a cutting head of 1.5 x D.