Disterhoft also employs BLUM's KinematicsPerfect software to enhance the machines' precision. This enables the kinematic accuracy of the 5-axis Fanuc machining centres to be measured fully automatically, influencing factors to be identified, and any inaccuracy corrected. To do so, a calibration sphere is measured at different swivel positions of the fourth and fifth axes. The measurement itself is performed with the aid of the measuring cycles developed by BLUM. "Based on the measured values, the kinematic error for each position of the axes is calculated and the kinematic parameter tables of the machine controller are automatically corrected as necessary. The machine can then compensate for the errors and attain a very high degree of precision," explains Alexander Disterhoft. "In the case of critical parts, we check the kinematic error – which varies as the machine heats up – by regularly measuring after finishing a defined number of parts. The calibration sphere is mounted on a pallet, meaning it can also be loaded automatically into the Fanuc machining centres."
For advanced data analysis, Disterhoft uses the KinematicsPerfect PC software, which enables the machine's kinematic performance to be easily visualized. Easily understandable visualisation of measurement results enables the precision of the machining centre to be assessed. Bearing damage or mechanical deformations of the swivel axes can be detected, as can circularity deviations and wobbling of the table or of a rotation axis.
The non-circularity indicator, especially, provides the manufacturer with a good feel for the precision of its machines. That's important particularly for the tiny spoons of biopsy forceps, the edges or splines of which have to fit precisely on top of each other, and which are milled in 5-axis mode. The measurement is also highly precise. Based on the measurement of the milled parts, Disterhoft knows that the Y axis of one of its machines has an error of 0.04 mm when cold. The measurement result using KinematicsPerfect was 0.039 mm!
If possible, Disterhoft manufactures around the clock. For that, it is necessary to perform measurements continually throughout the machining cycle. Each tool is measured by laser or tool setting probes after machining so that machining can be stopped if a tool is broken. Otherwise the subsequent tools would collide with the workpiece, as the workpiece would have been machined less than intended. This might have severe consequences, not only for the tools, but also for the spindle and the machine itself. Speed is also important to the Disterhoft, so that they can complete their orders on time. So it is essential that the Blum measuring systems are capable of withstanding very high speeds.
BLUM's production measurement technology has absolutely proved its worth at the company in Spaichingen. Thanks to the fast probing speeds – possible with both tool setting probes and touch probes – Disterhoft loses very little machining time. That is very important when production is running around the clock and many thousands of measurements a day are being performed. "Particularly when the machines are running automatically on night shifts, reliability is of course the top priority. We couldn't run them like that if they couldn't measure automatically," Waldemar Disterhoft stresses. "We are delighted by the Blum measuring systems, and by the level of cooperation from Blum. Especially as measuring time ultimately means machining time, and that generates revenue."