The high-energy micro-arc spark–computer numerical control deposition of planar NURBS curve coatings

Based on a 3-axis milling machine equipped with a FANUC 0i-MB system, a high-energy micro-arc spark–computer integrated deposition system (HEMAS-CIDS) is constructed through designing a special deposition holder. The traditionally manual high-energy micro-arc spark deposition (HEMASD) process is upgraded into a new process named high-energy micro-arc spark–computer numerical control deposition (HEMAS-CNCD) process on the basis of HEMAS-CIDS. Using powerful control abilities of CNC machines, the HEMAS-CNCD process can implement the deposition of NURBS curve coatings. Two interpolation methods and two deposition approaches are investigated for NURBS curve coatings, respectively. The two interpolation methods are the fixed step interpolation (FSI) and the fixed step plus binary-search interpolation (FS + BSI), while the two deposition approaches are the fixed step deposition (FSD) and the equi-chord length deposition (ECLD). The FS + BSI method is better than the FSI method because it can realize interpolation meeting the requirement of error with high efficiency. Experiments show that the ECLD approach can deposit a NURBS curve coating evenly. The smaller the chord length is, the more deposition points are, and the lower the deposition efficiency is. When the chord length is equal to 0.2 mm, a NURBS curve coating with relatively higher forming quality and efficiency is obtained.