Investigation of an Advanced Methodology for Automated Quality Inspection of milled CFRP-Edges through the Use of Image Processing of Infrared Images

The need to reduce greenhouse gases during the production and operation of airplanes presents a challenge to the worldwide aviation industry. The introduction of lightweight materials such as carbon fibre reinforced polymer (CFRP) over the last decades has led to new requirements in the overall process chain. The inhomogeneous structure of CFRP-components causes surface defects during the final contour milling like delamination, fibre fraying and fibre splintering. Based on a manual inspection specialized workers check whether a predefined defect tolerance has been exceeded. The manual inspection and individual post-processing of surface defects takes place while the machined component remains in the workspace of the machine. The current processing and quality inspection of CFRP-components has led to non-productive secondary times and because of this, the energy-consumption for every component produced is higher than necessary. This paper presents an investigation of an advanced methodology for the automated inspection of machined CFRP-edges. During the machining of CFRP-components, a thermal camera acquires images of the milled edges. These images are used to compare an idealized temperature profile within a workpiece with the resulting profile including surface defects. The comparison of the ideal and real temperature profile makes it possible to isolate the surface defects and to measure them.