Tool making and mechanical engineering
Machining is the most commonly used finishing process in the manufacturing of precision tools. The basic principle of machining is based on the intrusion of a v-shaped tool blade into the surface of the work piece. The blade can have an exactly defined cutting edge geometry or can be irregularly shaped. Tools with geometrically defined cutting edges include milling, drilling and turning tools. Grinding tools are tools with a non-geometrically defined cutting edge. The clearance angle, sharpening angle and cutting angle have a significant effect of the further machining process. Along the blade, there are cutting faces and open spaces, which should increase the stability, and thus the service life, of the tool. The chip grooves on the open spaces along the blade which bring or break the chip into the desired shape are another feature of a blade. In order to increase process reliability and efficiency, the tools must be manufactured and inspected with a high degree of precision.
Efficient tool measurement
In order to increase the stability and service life of the tool, micro geometries and roughness has to be very tightly tolerated and tested adequately. The blades are initially assessed using the cutting edge radius and the blade geometry. Using the optical 3D measuring technology from Confovis, the shape, edge symmetry, flattening and chipping of the edges can be determined alongside the cutting edge radius and angle.
Cutting edge determination
The edge symmetry is characterised using the K factor. When assessing surface quality, the roughness of the cutting faces and open spaces can be determined and assessed according to the DIN EN ISO 25178 flat roughness standard as well as according to DIN EN ISO 4278, which used to be common, by means of confocal measurements.
The tool manufacturer has data available for its finishing process which allows it to optimise the process parameters and thus achieve its optimal cutting performance in combination with an increased tool service life.
Focus variation and confocal microscopy in one system
This measuring task can be completed with no problem thanks to the combined measuring process using focus variation and confocal microscopy. Contours with large angles can be resolved using the process of focus variation. Roughness down to the nanometre range is captured with the patented technology of structured illumination as part of the confocal microscopy. In this way, one single measuring system measures both micro geometries and roughness on reflective surfaces with nanometre precision and in accordance with the standards.
Fast area scan provides extended 3D data
The confocal measuring points obtained by focus variation are fused into a point cloud and can be referenced to the CAD data by means of GOM software. In this way, a differential model can also be generated and the wear of the tool determined with an accuracy on the single-digit nanometer scale. These accuracies are required particularly when the opening cutting edge is analyzed in wear studies.