The heads for M6-M72 bolts are forged by induction heating. The heating parameters are determined with a pyrometer and the forging process is carried out in two stages to improve the mechanical properties and structure of the materials (dynamic impact strength). The automated forging process reduces the likelihood of errors. Our in-house tool shop allows us to achieve shorter tooling times between series. The forging process is quickly validated.
All our heat treatment processes are verified and computer controlled: tempering, normalisation, blackening, soft annealing, full annealing and selective hardening. This procedure ensures high levels of reproducibility and allows us to build a database, which is essential for further analyses and development. Heat treatment recipes are the result of ongoing training and know-how, accumulated over a span of 50 years.
Conventional turning of workpieces from 5 to 100 mm in diameter, on CNC lathes, and special turning of longer workpieces, from 8 to 70 mm in diameter, with a maximum length of 1000 mm. Thanks to our modern machine park, automation AND a high level of preventive maintenance, we are able to provide tight dimensional tolerances.
After the thermal treatment, the workpieces are threaded by rolling, up to the quality grade of 12.9. We provide metric threads, UN, UNC, UNF and BSW threads or threads according to customer specifications. The rolling process is CNC controlled. The thread rolling machines are fitted with a measurement system for measuring the force required for the transformation of material, hardness and the diameter of the shank, onto which the threads are rolled. In the event of deviations, the machine automatically rejects the material.
Proven grinding processes to ensure specified geometrical characteristics of the products. The most stringent tolerance ranges and precise product dimensions are achieved with the centreless grinding process: for machining large series workpieces with short lead times. In the process of centreless grinding material is removed from the workpiece by means of abrasive cutting.