Sensor based online quality monitoring system for detection of milling defects on CFRP structures

In the aviation industry, increasing research and applications of carbon fibres have led to a higher demand of carbon fibre reinforced polymer (CFRP) material. The moulding process of CFRP material is not precise enough to be directly moulded into its end form and an additional machining process is required. The machining of CFRP materials can result into generation of defects such as fibre overhang, cracking and delamination. Normally, the visual quality checks are carried out after machining is completed and hence, the damage at the end of the process is significantly more which can result into rework or rejection of the product. To solve this problem, an online quality monitoring system was developed in which the defects were measured, processed and identified online during the milling process. In order to achieve this, a line sensor was mounted behind the tool, which followed the tool and captured the data of the edge while milling. In the end, defects such as fibre overhang and delamination were detected simultaneously during the milling process.