Improving operational performance of wearing parts of the HK 33E / G3 infantry rifle mechanisms

In this study, it was aimed to determine the changes in wear performances of some parts that are worn in HK33E Infantry Rifles, produced at Kırıkkale Facility, after using these parts as uncoated and thin coated with CrN and AlTiN film.The extractor material which causes to throw the case out and the bolt handle which causes malfunctions in the rifles frequently because of wear, and also should be changed frequently, were coated with Aluminum Nitride (AlTiN) and Crom Nitride (CrN) by 16MnCr5(AISI 5115) and 32NiCrMo145 (UK Standard is 830m31) Ark PVD (Physical Vapor Deposition) method. Wear experiments and a component test were done according to ASTM standards, the planning of the wear experiments and the evaluations of the effects of the results that are obtained were done using Taguchi Experiment Techniques. In the experiments, base material, sliding speed, sliding distance, load, surface condition and work area were used as variable parameters.A variety of experiments were done on the AlTiN and CrN coated test samples in order to determine coating thickness, surface roughness, hardness and adhesion ability to the base material.Wear experiments were done on a flat surface with a ball on plate experimental setup. Since a measurable amount of wear could not be obtained from the coated samples, volumetric loss in the contrary material was chosen as the wear criteria compatible with ASTM G133 standards. Component tests were performed as simulating the working environment of the original components (bolt handle and extractor), the loss of weight and the change in profile dimensions were used as criteria.At the end of the Laboratory and Performance tests, it was observed that the wear lifetime of the samples coated with AlTiN and CrN increased 2 to 5 times and the best performance against wear was seen in the AlTiN coated samples. It is evaluated that the results obtained are in accordance with the literature.Key Words : PVD, Gun, Surface Covering, Tribology