Low-Threshold Retrofit Strategy for CNC Machines: A New Process Data Acquisition Approach

Abstract

The retrieval of process data from older CNC machines is hampered by the lack of machine control interfaces and sensors required for data acquisition. To address this problem, this paper proposes a low-threshold retrofit strategy for chipping machines (> 20 years of age) that enables the assessment of the current machining process and the quality of the manufactured components. Using commercially available sensor technology, the machining condition can be assessed during the machining process. In addition, temperature sensors are used to monitor the inside of the machine. This work shows that a change in the internal temperature of ~3°c can be correlated with qualitative dimensional variations of about 0.014 mm. This has implications for process capability and component quality in the $\mu$m range. This retrofit approach provides data on the machining process with little effort and leads to an improved assessment of productivity and quality. With this approach, process data can be collected from older machines and used to calculate the overall equipment effectiveness (OEE). As a result, unnecessary costs in production can be identified and eliminated, leading to a reduction in production costs and a competitive advantage in the global marketplace.