Enhancement of cutting tool surface coating quality using ionized gaseous medium (IGM)

The use of ionized gaseous medium (IGM) to prepare a hard alloy material surface by grinding and its effect on the coating quality was investigated. During grinding, IGM was fed to the cutting area by different methods namely: clockwise (longitudinal), anticlockwise (opposed) and transverse (Cross) feeding, respectively. Thereafter, the samples were coated with a titanium nitride on a modern vacuum, ionizing apparatus HHB-6.6-u1 by physical vapour deposition (PVD) method, known as condensation and ionized bombardment (CIB). The analysis of the results and tests carried out revealed that IGM improves the quality of coating, especially when IGM was fed anticlockwise and when the corona discharged current (tk) was equal to 50 mA. The lowest component forces were also gotten by anticlockwise feeding for example, the component forces (Py Pz) were 2 times and 1.5 times lower compared to longitudinal and cross feeding of IGM, respectively. The micro hardness of inserts ground with IGM was about 10% higher than those ground with other types of fluids. The micro photograph of inserts structure revealed a distinct and better coated layer for the inserts surfaces prepared prior to coating with IGM. Whereas inserts prepared with compressed air and without cutting fluids showed very blur and indistinct coated layer. It was established that inserts whose surfaces were prepared with IGM and then coated with the titanium nitride (TiN) showed tool-life of about 4 times greater than others.   Key words: Ionized gaseous medium, hand alloy tool inserts, coating, condensation and ionized bombardment, titanium nitride.