Vibration is ever-present during the machining process, and it can result in inadequate surface finishes, insufficient accuracy, high machining noise, shortened tool life and — in extreme cases — broken tools.
However, the level of vibration can be controlled in a variety of ways, as demonstrated by Rugby-based MapalLtd (www.mapal.com
) with its latest vibration-damping tool-holders.
Very long tools used for boring and milling tend to vibrate due to insufficient dynamic rigidity, so when designing this new tool-holding system, Mapal’s product developers considered all aspects of the machine tool, the cutting tool and the type of clamping — even the component.
The company says the result is “a system for vibration damping that is matched to all common types of machine stiffness and can be used for machining different types of materials with a variety of cutting tools.
“The tool bodies incorporate a self-contained system of auxiliary mass and several steel spring packages configured to counteract the deflection of the tool body and minimise it”.
Mapal says the level of vibration ‘suffered’ when using its new system can be up to 1,000-times lower than when using tools without the absorber system; “and even with long tool projection lengths, quiet and stable running is achieved, and tool performance is significantly improved”.
This makes it possible to work at higher cutting speeds and increased material removal rates.
When milling case-hardened steel (16MnCr5) with a 250mm-long combination of a vibration-damping milling-cutter arbor and a 50mm-diameter milling cutter with five cutting edges and ISO indexable inserts, the Rz value was halved from 7.8 to 3.9µm (for a radial depth of cut of 18mm and a depth of cut of 3mm) compared to the same tool system without vibration damping.
Mapal’s milling-cutter arbors with vibration damping in the shank are available with an internal coolant supply for clamping diameters of 16, 22 and 27mm, with lengths of 200 and 300mm.
They are currently available for SK40, SK50, HSK-A63 and HSK-A100 connections.