Selection of cutting parameters of turning the Ni-Al and Ni-Al-Al2O3 flame sprayed coatings

The process of flame sprayed is a technology affordable and easy to implement. It does not reąińre great skill of the operator. This method is not associated with expensive workstation equipment. It may therefore be used with successfor the regeneration of machine parts bv the crew of vessel engine room. Flame sprayed coatings are characterized by porosity, oxide inclusions presence and large real area of surface. In order to obtain adequate surface roughness coatings must be applied finishing. For this purpose, the turning and grinding are used. In the paper a turning to finishing flame sprayed coatings was proposed. Coatings of Ni-5%Al and Ni-5% Al-15% Al2O3 obtained by powder flame spraying, were studied. Torch of "Casto-Dyn 8000" was used. In practice, the substrate and the t herma l ly sprayed coating are processed by the same cutting tool. For example, Messner Eutectic Castolin company offers r\vo types of tools: "Rototool II/" (square insert) and "Rototool III" with a removable cylindrical insert. Average surface roughness of coating after machined tool "Rototool II" was Ra = 3 mi m. This surface often requires grinding. The different tool geometry was suggestedfor better texture of coatings surface. Workpiece was machined by tool with CBN insert WNGA080408S01030A mounted in holder DWLNRL-2525M08 (cutting inserts beta = 80°, approach angle Kr = 95°, nose radius - 0.8 mm, relief angle alfa = 6°, rake angle gamma= -6°). The influence of cutting speed, feed rate, depth of turning on the coating surface roughness was estimated. The following cutting parameters: cutting speed Vc = 45-214 m/m in, feed rate f = 0.06-0.2 mm/rev, depth of cut ap = 0.05-0.3 mm. The lowest value of the roughness of the alloy (Ra = 0.5 mi m) and composite (Ra = 0.8 mi m) coatings were obtained by using cutting parameters: Vc = 214 m/min, f= 0.06 mm/rev, ap = 0.4 mm.