Noise is vibration and vibrations can be detrimental to machining. Although vibrations are part of the machining process, it is when vibrations reach unsatisfactory levels that they become a problem.
Milling, as an intermittent cutting process, is especially prone to vibrations and when milling is performed with cutters at a long overhang, productivity is all too often compromised. This does not have to be the case using a new-generation of dampened tool-adaptors dedicated to specific ranges of tool reach.
Sources of vibration
There are various sources of vibrations in machining. In milling, these can be varying entry and exit of cuts, cutter performance, unstable workpieces or part-features and when there is a long tool overhang. Many sources can be countered through the correct application of the right milling cutter, inserts, tool-path, stabilizing measures and good tool-holding. Longer tool-overhang is to an increasing extent another demanding parameter, which needs additional measures to minimize effects on machining and for productivity to be boosted. In milling operations, the axial-depth-of-cut and feed are at risk of having to be kept unnecessarily low at overhangs starting at four times the cutter diameter – thereby directly affecting metal-removal rates, cost-per-component and through-put times.
A new generation of dampened adaptors for tool holding in milling has been developed as part of the Silent Tools programme. This has resulted in the introduction of a new system using two lengths of dampened adaptors, one dedicated, for milling with overhangs of 4 to 5 times the adaptor diameter and one for 6 to 7 times the diameter. Beyond this reach, engineered dampened adaptors form the solution for higher productivity.
The cutting tool is negatively affected by deflection forces and cutting forces as overhangs get longer. Vibrations cannot be entirely eliminated but with modern dampened adaptors they can certainly be moderated to levels where they do not pose threats to the process and results. Advanced simulation methods, equipment and metrology systems are used today, backed by the deeper understanding of the structural dynamics involved to counter the effect of forces acting on the tool.
..and then quality
The results of these developments are a real increase of the dampening function itself along with the ability to more accurately target functionality to specific tool-overhang ranges. Two new standard adaptors provide tool reach that does not limit performance, from the machine spindle to cutting edge through the ability to level out the vibration amplitude typical of the particular area of tool overhang.
Silent Tools milling tool adaptors go beyond being a problem solver in that they have a new potential for higher productivity. They also introduce new possibilities of machining cavities and to reach beyond component features, such as when using over-size diameter milling cutters. The new tooling potential can also be translated into extended overhang or a combination of higher productivity and longer tool reach. The most common areas of longer tool reach in milling are covered by these adaptors. The direct productivity increase achieved by the new tool holding provides a short payback time from the initial adaptor investment.