A Quantitative Method for the Investigation of Digitized Surfaces After Fine Milling Machining

Due to increasing efforts to shorten the time to market of new vehicle models, press tooling is under increasing competitive pressure. The manufacturing of press tools for high-quality body components depends on a large extent on the quality of the tools active surfaces as free-form surfaces. The use of non-contact optical measurement methods to digitize the tool surfaces creates high-density point clouds that have great potential to improve the manufacturing process through their analysis. In this paper, a method for the analysis of these point clouds is presented, which combines the qualitative and quantitative analysis of active surfaces, to enable conclusions about the process strategy and allow further optimizations to achieve cost and time savings. It is demonstrated on the example of a test specimen with characteristic elements of a press tool for vehicle body components. A parameter SQ is defined, which describes the area percentage inside of tolerance limits, acting as a quality parameter for the manufacturing result. The used test specimen achieves a SQ value of 93.9%. The robustness of SQ is investigated by a variation of the tolerance limits and a possible applicability to other components outside of vehicle body components is considered. Furthermore the distribution of the shape deviation is evaluated to determine whether too much or too little material removal causes the deviations, as well as in which angles it mainly occurs. It can be shown that the qualitative analysis of the false color image can be confirmed by the quantitative results of the proposed method. Based on this, optimization measures for the machining process are derived.