A tool for drilling and milling in smallest spaces
Plunging vertically (drilling), milling a groove into solid material and subsequent final finishing all in one operation. With its CrazyMill Cool P&S the Swiss cutting tool manufacturer Mikron Tool brings a cutting tool to the market, with which all of this is possible. Who needs to mill grooves and pockets in the smallest of spaces will really appreciate this new tool. A typical is the milling of key ways as used for drive shafts of motors.
Drilling and milling have each one their very specific characteristics. To combine the strengths of both operations in a single tool is quite demanding. Especially if small diameters are involved and when the result has to be reached efficiently, process stable and with high precision. This new 3-flute solid carbide plunge mill has some different features which make it a really unique tool.
Due to a special cutting-edge geometry a process stable and vibration-free plunging (drilling) is possible. A correction in the center stabilizes the central cutting edge and reduces the penetration force. The especially large chip area in the top section permits to absorb a good quantity of chips during the drilling process and then evacuates these laterally into the equally enlarged chip flutes. Adapted chip and relieve angles together with stable cutting edge corners avoid lateral hooking up and the subsequent breaking out of the cutting edges due to vibrations, which is one of the central problems when “drilling” with a milling cutter. (picture 1)
Just as with other mills of the CrazyMill Cool family (two and 4 flutes) this new tool has coolant ducts integrated in the shank which bring the coolant directly to the cutting edges and afford a constant and targeted cooling. This prevents the overheating and chipping of the edges even with high speeds and feeds. Furthermore, with this the chips are continuously flushed from the milling area, which is not a given, especially in tight and angled spaces, with conventional external coolant supply. (picture 2)
These factors (geometry and cooling) combined with a heat- and wear resistant coating and the use of an ultrafine grain carbide guarantee the extraordinary performance of this new tool. Mr. Schnyder, key responsible of Mikron Tool International points out the impressive chip removal rates, which are possible with the high speeds and feeds and a chip removal rate (ap) of 1xd. He assures also that tool life is at least double or more of what can generally be expected with conventional tools available today on the market. This comes really into play with small diameters in stainless steels and titanium. Important is above all the tool integrated cooling, which flushes the chips continuously from the working area before these are broken up into small pieces and thus would damage the surface of the work-piece.
A few criteria have to be considered when choosing the right milling cutter in order to reach the desired result. When machining a keyway for instance, a lateral finish milling is necessary and therefore the tool diameter has to be chosen accordingly. Generally, the tool manufacturer recommends to adhere to the guidelines in regards to the indicated cutting parameters for drilling and milling processes.
A practical example: (picture 3) With this new plunge-mill a keyway of a gear work-piece is milled from A to Z. In the first step the mill (diameter 2mm/.079”) plunges vertically in to the material, directly down to a depth of 1 x d, with a speed of 120 m/min (394 SFM) and a feed of 0.002 mm (.00008”) per revolution and flute. Subsequently the groove is milled into the solid material, while maintaining a feed of 1xd, increasing the cutting speed to 200 m/min (656 SFM) and the feed to 0.007 mm/Z (.00028”). With the finishing operation the final keyway dimension as well as required surface quality are reached.
CrazyMill Cool P&S is available from stock in diameters 1 to 6 mm (.039” to .236”) and for milling depths up to 2.5 x d. All milling cutters have a high-performance surface coating and feature 3 to 5 shank-integrated coolant ducts.