Vollmer is a world market leader in the manufacture of sharpening and eroding machines that are employed in tool production and maintenance. Vollmer developed the new Vpulse eroding generator for machining state-of-the-art polycrystalline diamond (PCD) tools.
Before the new machine could be implemented, it was necessary to establish the ideal erosion parameters to determine precision, quality, and efficiency. For this purpose, Vollmer utilized Alicona’s measurement systems to measure the finished tools.
Vollmer benefits from Alicona’s solutions for accurate, repeatable edge preparation measurements with close tolerances and for high-resolution 3D surface measurements.
Machining of PCD tools
PCD is an exceptionally hard matrix of synthetically created diamond particles. It has found widespread usage in the manufacture of cutting tools.
In the machining of highly abrasive light- weight materials, cutting edges made from polycrystalline diamond provide customers with significantly longer tool lives compared to carbide cutting tools and ensure more precise machining of plastic, aluminum, magnesium, and wood.
Arndt Hauger, Product Manager, Hybrid Processing
Electrical discharge machining enables extremely accurate sharpening of cutting edges. This technique involves using electrical currents to generate discharges that subsequently remove microscopic quantities of material from a workpiece. To carry out edge rounding on PCD tools, it is crucial to perform proper edge preparation of the cutting edge, because it is this feature that governs the service life and quality of a tool.
Alicona’s InfiniteFocus System for Measuring Finished Tools
Posed with the task of eroding PCD tools with optimal quality, Vollmer was looking for a flexible measurement system that could perform repeatable and robust measurements to verify clearance surface, edges, and chipping. Alicona has provided Vollmer with a means for precise inspection of the aforementioned quality features and for the identification of optimal machining parameters for its Vpulse eroding generator. In turn, Vollmer’s customers benefit from maximum accuracy and higher reliability in eroding the PCD tools.
As Arndt Hauger reports, “Thanks to the repeatable measurements by Alicona we have managed to strike the perfect balance between efficiency and quality in the machining of PCD cutting edges.” For identifying optimum machine parameters, Vollmer performs measurement of finished PCD tools. High-resolution, repeatable measurements of the geometry and topography of a tool’s clearance surface (Figure 2) can be acquired by using Alicona’s InfiniteFocus system.
Figure 2. 3D surface texture measurement: roughness verification over the entire clearance surface. Identification of height differences with 3D visualization based on real color information.
Examining Clearance Surfaces by Measuring Roughness
A workpiece’s roughness is also governed by a tool’s clearance surface, since it has an impact on the chipping along the cutting edge. Alicona’s 3D areal surface-texture measurement enables Vollmer to investigate the entire clearance surface roughness, including its curved parts. The measured values comprise profile-roughness parameters (Ra, Rz), volume parameters, areal parameters (Sa, Sz), and bearing area curve. Impurities or burns can be easily identified by employing true-color 3D surface visualization (Figure 3). The true-color information for any point of measurement can be obtained by means of focus-variation. Arndt Hauger confirmed that “The true color pictures make it possible to quickly assess the results.”
Figure 3. Radius and form measurement of edge rounding up to 3µm to increase tool quality and service life.
Assessment of Cutting Edge Quality
Besides verifying the surface texture of the clearance surface, Vollmer employs Alicona’s systems to also measure the cutting edge geometry to check for cracks.
The main measurement parameters are radius, wedge angle, and chipping.
Arndt Hauger, Product Manager, Hybrid Processing
Alicona’s Chipping Module was employed by Vollmer for identifying chipping on the cutting edge (Figure 4). 3D difference measurement can be used to assess other form deviations, which involves comparison of the cutting edge geometry with reference geometry or an imported CAD dataset through a completely automatic process. Form deviations can be automatically detected and visualized by using a special color coding.
Figure 4. Chipping measurement along the edge to improve edge stability.
The following parameters of a PCD cutting edge can be measured by using Alicona’s InfiniteFocus system:
- Roughness of the clearance surface (Ra, Rz, Sa, Sz)
- Bearing area curve
- Form deviations to imported CAD dataset
Arndt Hauger concluded by saying “Our customers profit immensely from our ability to measure the geometry, edge radius, angles and surface of PCD cutting tools after machining. It enables us to provide our clients with a more reliable and consistent service. Thanks to the optimum machine parameters for the new Vpulse eroding generator, we are now able to machine PCD tools 30% faster, possible surface quality has improved by a factor of two and above.”
This information has been sourced, reviewed and adapted from materials provided by Alicona Imaging GmbH.
For more information on this source, please visit Alicona Imaging GmbH.