How to Determine Process Fluctuations in Wire-Arc Spraying

Wire-arc spraying is particularly used for large-area coating due to the high cost efficiency of the process. The process is also characterised by strong process fluctuations. Nowadays, a costly and time-consuming inspection is required after coating in order to identify and eliminate possible coating defects and insufficient coating thicknesses caused by the process instability. Therefore, a sensor unit with seven channels is established, which realises an in-situ monitoring of the process. Additionally, a statistical design of experiments that variates the process parameter and therefore will generate a large amount of data is conducted. For a deeper understanding of the process and its performance, the surface is characterized by confocal laser scanning microscopy and cross-sections are investigated using SEM as well as light microscopy. The new and unique sensor unit is successfully established for the wire-arc spraying. Moreover, the recorded sensor data are displayed and compared within the parameter variation. The parameter variation showed an influence on the coating properties such as coating thickness. With the prototype of the new and so far unique sensor unit, process parameters can be recorded at a high resolution. By continuously evaluating the process fluctuations quality requirements can be ensured.