Process monitoring in grinding using micromagnetic techniques

In production engineering, the demands on monitoring systems are steadily i ncreasing owing to the automation of machining processes. In the past, the detection of defects was sufficient. today, the avoidance of any defect is necessary. Therefore, monitoring systems have to be fast and reliable to gu arantee zero-defect manufacturing. Most systems monitor acoustic emission ( AE), power consumption or forces while machining. Thus, the quality of the workforce is only indirectly described and the determination of workpiece q uality characteristics must be made by metallographical inspections of rand om samples. These investigations are time-consuming and often destructive. Micromagnetic techniques make fast and non-destructive quality control of g round workpieces possible. For post-process measurements, the magnetic quan tities of Barkhausen noise and field strength are used. The sensor systems have been adapted to different applications such as grinding of gears or be aring rings. In this paper the basic principle of this technique and the re sults of industrial implementation will be presented. A new micromagnetic a nalyzing system will be introduced which can be used for the direct measure ment of workpiece quality characteristics while machining. This system uses twelve different magnetic parameters and is a combination of the above men tioned system and an eddy current analyzing system. Residual stresses, surf ace hardness and can be used for process control. Furthermore, the 100% qua lity documentation is possible without any additional post-process measurem ent. In addition to the measuring principle, first results and examples of automotive applications will be shown.