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 shorter bore spacing, improved thermal transfer, low bore distortion, increased resistance to corrosion and abrasion, reductions in weight and friction, enhanced durability, and product cost savings. For automobiles, this leads to the potential for increased power, improved 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 coating. Therefore, in situ monitoring of wire curvature is desirable for producing reliable and high quality PTWA thermal spray coatings.