Enhancing Production Control for PTWA Engine Bore Coating

Plasma Transferred Wire Arc (PTWA) is a well-established thermal spray process that is used in high-volume production by multiple automotive OEMs. Benefits of these PTWA thermal spray coatings include closer bore spacing, improved thermal transfer, lower bore distortion, increased resistance to corrosion and abrasion, reductions in weight and friction, enhanced durability, and product cost savings. For automobiles, this leads to increased fuel economy and lower emissions. Millions of engine cylinder bores per year are coated using the PTWA thermal spray process. To ensure optimal surface coatings, it is vital to monitor the process variables. Although some process monitoring already exists in current production, new technological advancements allow for additional variables to be monitored. Arc voltage is of particular importance as it can be viewed real-time in situ to the PTWA process to determine the curvature of the feedstock wire. Straight wire is ideal for achieving peak system performance. If the wire has excessive curvature, it can lead to out-of-tolerance conditions that detrimentally affect the quality of the surface coating. Therefore, in-situ monitoring of wire curvature is both desirable and necessary for producing the highest quality PTWA thermal spray coatings possible.