Gears are commonly used in every field of industry as power and motion transmission elements. According to the usage areas, they are manufactured from materials such as steel, aluminium, plastics, cast and bronze. There are different manufacturing methods according to material type. Plastic gears are preferred in textile, automotive and aviation industries where the supported load is low, and corrosion and lightness are considerably important. They work more quietly than metal gears. Plastic gears are manufactured by an injection moulding or hobbing method. The disadvantages of the plastic injection method are high cost of the injection moulds and strength losses in the moulded parts due to the internal clearance faults, whereas the disadvantage of the hobbing method is defects in tooth profiles due to operational faults. In this study, wear strengths of plastic spur gears manufactured via a three-dimensional printer with the fused deposition modelling technique as an alternative manufacturing method were experimentally examined. In the experimental studies, polylactic acid pinion gear manufactured with the three-dimensional printer was subjected to wear tests with St37-2 gear. Wear strengths of plastic spur gears were compared in wear tests performed with Forschungsstelle für Zahnrader und Getriebebau equipment under various loads and rotational speeds. Wear depths that occurred in plastic gears were examined via coordinate measuring machine equipment. As a result of the experimental studies, it is found that wear is increased with the increase of load affecting the gear, and wear is decreased with the increase of rotational speed. As a result of this study, it was shown that plastic spur gears manufactured with three-dimensional printers can be used in areas where lightness and corrosion resistance is important under low loads.

Internal gears are often used in the automotive industry when two gears are required to rotate in the same direction. Tooth shapes, slippage speeds at the beginning and end of meshing are different according to the external gears. Manufacturing of internal gears is more difficult than external gears. Thus, it is necessary to determine the working conditions and wear behavior of internal gears carefully. The profile modification method in terms of strength and surface tension of the gear mechanism are performed in order to increase the load-carrying capability. In this study, profile modification method was performed in the internal gears to reduce the wear on the teeth. For this purpose, the wear of the internal gears was theoretically investigated by adapting the Archard wear equation to the internal gears. Closed circuit power circulation system was designed and manufactured to experimentally investigate the wear in internal gears. With this system, wear tests of gears made of St 50 material without profile modification and different profile modifications were made and the results were compared. Experimental study was performed in the same loading and cycle time conditions to validate the theoretical results and it was seen that the results are compatible. According to the experimental results, it is seen that in the internal gears, when profile modification done the wear is decreased in the teeth tip region.

One of the most important problems of automotive engineering is joining metal sheets, thin-walled tubes or profiles simply, efficiently, and economically. After conventional drilling and tapping in thin-walled materials, the strength remains low due to the small number of teeth and the connection can be easily unfastened. For increasing the strength there are several solutions such as using welded nuts, tapped rivets and welding extra nuts. Since nut welding cannot be done on the inner surfaces, these solutions are inadequate for square and circular tubes. In this study, holes of various diameters were drilled on 1.5 mm thick AISI 304 stainless steel and EN AW-6060 square and circular profiles by flow drilling at various rotational speeds, and then flow tapping was applied to the holes. The same processes were repeated with conventional drilling method to compare bushing heights and clamping strengths of the parts as well as the hardness values and capillary crack formations around the holes. According to the results obtained, the strength in flow drilling and tapping increases by 50-55% compared to the classical drilling method. The reason for this is that as the hole diameter increases, the amount of material plastered and the number of threads required for screwing increases approximately 2.5-3 times. Capillary cracks, which are observed in holes drilled with the traditional method as the hole diameter increases, are not observed with this method and thus increasing the strength of the connection.