Mikron’s CrazyDrill up to 40xD in one stroke
Small, deep and fast, these are the characteristics of the small drill CrazyDrill Cool SST-Inox. Due to internal coolant ducts, innovative geometry, and its coating, the machining of stainless steels, nickel-based super alloys, and CrCo-alloys has become a significantly simpler, more stable process. This goes also for small diameters as well as deep bores.
The CrazyDrill range includes through coolant drills in six different working lengths: up to 6xD, to 10xD, to 15xD, to 20xD, to 30xD, and to 40xD. In addition, there is a short i.e. pilot drill for a max bore depth of 3 x d. Up to a bore depth of 20xD these tools are available from dia. 0.039” (1mm), the longest one from 0.078” (2mm). The entire range goes to a max diameter of 0.236” (6mm).
Drills with spiralized coolant ducts are already available, however many get into trouble with tough-elastic materials or with the poor heat conductivity of super alloys. Here the cooling through classic round ducts is insufficient even with high pressure. A premature edge chipping, packing of chips, and buildup of flutes prevents a stable drilling process.
A new geometry provides a chip-breaking effect at the front with short and curved chips the result. In the back, an open flute profile facilitates perfect evacuation of microchips. There is a variant for long drills and in addition to the open profile, flute polishing helps evacuation chips from the bore along with the new coating for machining stainless steels.
Performance and process stability is by cooling of the tool: two spiralized, internal coolant ducts up to the drill tip, guarantee a constant and massive coolant flow during the entire drilling process, preventing tool overheating even with high cutting speeds. The drop shaped coolant ducts have the largest possible diameter and are in an area with little stress, so stability of the tools is not jeopardized. Compared to a conventional round diameter, these ducts afford a 4x higher coolant flow. At diameters under 0.118” (3mm) a power chamber in the shaft reduces the length of the ducts and provides higher coolant pressure.
The advantage of the efficient supply of coolant to the drill tip, increases tool life because overheating of the cutting edges is avoided. Combined with the tip geometry, cooling helps break and flush out the chips from the flutes. All these characteristics make it possible to work with higher cutting parameters (speed and feed) and to drill in one single stroke.
Long, longer and longest
Starting with drills for a depth of 10xD, little by little new and longer versions were introduced until the presentation of the complete range including 30xD and 40xD.
Why also a short drill?
When drilling deeper holes of 15xD or more it helps to have a short pilot operation to reach a high positioning accuracy. It also helps to guide the subsequent long drill and guarantees good straightness. So that this centering fits perfect, Mikron Tool developed the complimentary pilot drill whose tolerances are precisely tuned to the long drills. If requested the tool can also simultaneously do a chamfer of 90°. According to the long drill It has the internal coolant to the tip and is available in diameters from 0.039” to 0.236” (1mm to 6mm).
A customer works with a classic drill with round cross-section coolant channels and reaches a tool life of 3,900 bores per tool. With the new tool he reaches 18,000 parts; changing one tool saves $15,000 per year.
For the machining of a medical part (bore diameter 0.156”, depth 2.68”) made from chrome-cobalt a user had trouble to find the right drill, guaranteeing a stable process. Only with this new tool he had success – drilling in one stroke without pecking.