Many metals and plastics tend to generate long, stringy ribbons or nests of material when turned, grooved and drilled on a lathe. It risks damaging the tool, as well as the component being produced, and reduces productivity due to the need for frequent machine stoppages to remove entangled swarf.
Chipbreaker geometry moulded or ground into the face of cutting inserts helps to encourage swarf to break more frequently, but it is not enough if the workpiece material is particularly ductile.
High-pressure coolant directed to the point of cutting can help. Another way around the problem is to include canned cycles or macros into a program, but these consume extra time and reduce productivity. Some lathe manufacturers send oscillation signals to axis servo motors, but the vibration propagates through the entire mechanical drives of those axes, which takes a toll on the machine structure.
Now there is a different alternative to consider, following the invention by a German company,
VibroCut GmbH, of a range of vibrating toolholders that may be used in any driven station in the turret of a fixed-head lathe, including vertical turning centres.
VibroCut Oscillate is manufactured and distributed under license exclusively by a separate German firm, driven and static toolholder manufacturer
Wendel Tools which is represented in Britain and Ireland by
Nydaloxe Precision.
For clarity, it should be noted that although the toolholder is located in a driven station in the turret, it cannot deploy a live mill, drill or other rotating cutting tool. The unit is purely used to generate reciprocating motion to assist chipbreaking when using stationary turning tools, grooving and parting blades and boring bars.
The system utilises a defined, one-dimensional tool oscillation to introduce predetermined breaking points into the swarf, ensuring robust, predictable and controllable chipbreaking, either with cut interruption (air cutting) or without.
It produces short, manageable chips across all materials, including difficult-to-machine stainless steel, nickel-based alloys and plastics, regardless of cutting values, tool geometry, tool wear, or variable quality across material batches.
The technology does not extend the cutting cycle time for any given component. Oscillation is generated using a mechanical system inside the toolholder itself, whereby a mechanism converts rotation from the lathe turret's driven tool motor into axial reciprocating motion at the cutting tip, without subjecting any of the machine’s axis guideways and ballscrews to continuous oscillatory stress.
Users are able to fine-tune chip length by setting the oscillation frequency in the part program and manually adjusting the amplitude on the toolholder body. The VibroCut Oscillate chipbreaking solution is seamlessly retrofittable across any make of lathe whose turret uses a standard toolholder interface. They include VDI 25 through to 70 and BMT 45 up to 75, with special toolholder versions available on request. The tool-side interface is Capto.
There are three product series to accommodate various production needs - compact, standard and heavy. Non-resonant, low-frequency oscillation is set between 1 to 100Hz, stroke is adjustable up to 0.6mm and maximum process force is 12kN, depending on toolholder variant. Internal and external coolant supply is supported at pressures up to 20 bar.
The toolholders are available in two types to support diverse kinematic requirements: T-Line, which features oscillation at right angles to the tool drive axis; and L-Line, which provides in-line oscillation. Together, these configurations accommodate an extensive range of machining operations, including external longitudinal turning and grooving, face turning and grooving, boring and axial drilling.