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The new evolution in trochoidal milling

06/22/2016

For most manufacturing companies nowadays, process optimisation with regard to shorter machining times and an extended service life for the metal cutting tools are the keys to greater efficiency. Intelligent milling strategies, such as the trochoidal machining process, are the solution: in conjunction with the new CircularLine CCR end mills from WNT, tool service lives can be extended and components produced even faster.

Over the last five decades, the demands placed on the machining industry have changed considerably. On the one hand, components are becoming ever more complex; on the other, companies are under immense time pressure and must minimise personnel and machine costs. To remain competitive in the short and long-term, it is becoming increasingly important to fully exploit new technological advances as they become available: advances such as the trochoidal milling strategy. This ensures optimum and effective machining processes thanks to the use of new CAM programming systems and control cycles. Together with the right tool, this machining strategy offers some attractive benefits, including increased process reliability and noticeable time and cost savings.

The benefits of trochoidal milling are particularly noticeable when machining high volumes, deep slots or high flanks. In addition to extremely high process reliability and considerable time savings, an increased service life can be achieved, along with reduced tool wear. This is because the angle of engagement remains as small as possible during trochoidal milling, reducing the vibration caused. Also the fact that the end mill has more time to cool down during the process reduces the amount of wear.

Another particularly interesting aspect is the raw material utilisation of the carbide. Although the amount of carbide powder required to produce the tool is somewhat greater, the cutting length of the tool is twice as long. Wear in relation to the volume being machined is therefore distributed across the entire length of the longer cutting edge. If this is compared again with the raw material input, the result is positive and absolutely cost-effective.  Due to the higher radial forces, greater demand is placed on the tool, which requires special, more stable core geometry. Furthermore, both the carbide and coating must have high thermal shock resistance, as the temperatures generated at the cutting edge fluctuate strongly due to the engagement and cooling intervals. If the wrong tool is selected, micro-cracks may form on the cutting edge or chipping may occur.

The new CircularLine CCR end mills from WNT possess all these properties and are the first choice for optimum results with the trochoidal milling process. As demonstrated in particular by the application of the legendary Dragonskin coating, maximum emphasis has been placed on ensuring that the end mills exhibit a high degree of resistance. Like all high-performance tools that have a "Dragonskin", the new CCR end mills are extremely robust and wear-resistant and can withstand strong temperature fluctuations. These end mills also boast a special chip breaker that is ground into the cutting edge geometry. The need for this becomes apparent when considering that chips produced by a cutting length of 4xD and a diameter of 12 mm without a chip breaker, for example, would be 48 mm long. The chip breaker restricts the chip length to 2xD and optimum chip removal is ensured, even for problematic materials. Two versions of the WNT end mills are available: one for universal applications and another specifically for the machining of aluminium. While the six flutes of the CCR-UNI ensure smooth operation and a high material removal rate, the four flutes of the CCR-AL ensure a high depth of cut. They are available in 3xD (steel) and up to 4xD (aluminium) cutting lengths, and can reach cutting depths that correspond to these cutting lengths.

Tests have shown, it is possible to use significantly higher cutting data when using trochoidal milling with CCR end mills than with conventional machining processes, shortening machining times considerably. Even applications that were previously considered to be very difficult could be dramatically improved. In the past, problems were always encountered with chip evacuation for materials such as stainless steel 1.4404 (Duplex-VA). Unusually for this material, it was completely dry machined during the tests, leading to the discovery that the thermal shock effect could be minimised. As a result, a considerably longer service life is possible than with wet machining. In one case, the conventional machining time for the workpiece was reduced from 12 minutes to 5 ½ minutes and the general service life was tripled. These figures clearly show what combining the optimum tool with the right machining strategy can achieve.

A visual representation of the gains that can be made using CircularLine CCR end mills and the trochoidal machining process can be seen in this video: 

Anyone interested in the trochoidal machining using the CircularLine CCR end mills can contact WNT (UK) via the website at www.wnt.com or call the Freephone number 0800 073 2073 to request a visit by one of WNT’s specialist Technical Sales Engineers.

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