Safety of Machinery - Proposals for an Improved Workpiece Clamping in Machine Tools and Its Implementation in Product Safety Standards

The precise alignment of the clamped tool and workpiece is crucial to ensure precision and reproducibility in production. Modern CNC (Computerised Numerical Control) technologies enable automated control of these machines, allowing complex parts to be manufactured with high precision and efficiency. This process is critical in various industries, including automotive, aerospace, medical and many others, where high-precision metal parts are required. In doing so, the safety of workpiece clamping is of crucial importance in metalworking and other manufacturing processes. Improper workpiece clamping can lead to dangerous situations that can cause both personal injury and property damage. Various safety precautions are taken to ensure the safety of workpiece clamping, including the use of safe clamping devices, regular maintenance and inspection, operator training and adherence to safety guidelines. CNC machines may also be equipped with sensors and safety devices to detect unusual vibrations or movements and automatically shut down the machine in the event of a problem. The reliability of workpiece clamping when turning without support elements is particularly dependent on the clamping force applied and the process loads on the lathe chuck. It is therefore essential to correctly determine the process-dependent minimum clamping force required and to ensure that it is maintained during the process. The latter is addressed by innovative sensory jaws, which make it possible to record and control the clamping force in the clamping and turning process. As a guideline, instructive regulations exist for determining the clamping force of jaw chucks. In the Research Institute of the German Machine Tool Builders' Association (VDW), the interactions between the process, workpiece and clamping system were analysed in detail with the help of innovative measurement concepts using sensory jaws, and improved instructional specifications were derived.

Keywords: Safety, Reliability, Machine tools, Workpiece clamping, Sensory jaws, Product standards.