Improving carbide cutting tool performance through coating

The purpose of the work is to choose the most rational coating for the specified operating conditions of the metal-cutting tool. The rationality is estimated by the operation time until the rear surface wear becomes less than 0.5 mm. The study is given to the influence of coatings on wear resistance of carbide replaceable inserts of turning cutters at the external machining of billets made of stainless specialized hard-working steel of grade 09Х17Н7Ю. The application field of this steel has expanded considerably, while the recommendations for its machining are outdated. As a benchmark for rationality calculation is taken the operation time of domestic carbide plates made of VK8 grade alloy. Consideration is given only to square replaceable carbide inserts with a central base hole, the side length of a square is 12.7 mm. The need for the study is determined by the fact that available recommendations on the processing modes and choice of tool material for this treatment of the specified stainless steel are physically outdated (there are no machines of those models and tool materials). New recommendations are required for modern conditions. An experimental method is used to study the performance of various tool materials (VK8 substrate + a particular coating) by estimating the increase in the amount of tool wear on the rear surface over the time. For the specified operating conditions, a reserve has been created to form a database for the selection of cutting modes and tool materials. The influence of the choice of coating on the increase in tool wear resistance is shown. As a result, the preferred coatings that allow to conduct a lasting processing without cutting edge replacement have been identified. It is determined that the considered tool materials are substantially unequal by their wear resistance. The preferred tool material is VK8 + Ti(up to 1 µm) + TiN(1 µm) + (NbZrTiAl)N(2.5 µm) in which the coating layers are applied by condensation by ion bombardment with droplet filtration and assisting accelerated ions.

turning, stainless steel, wear resistance, carbide tool, coating