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The paper covers a single cutter lathe thread turn milling simulation that significantly reduces physical testing costs. The turn milling process involves a synchronized tool (helical mill), and workpiece rotation with a radial oncoming feed through a mill and workpiece relative movement. The cutting rate occurs by the mill teeth movement over the workpiece. The machining depth in each pass varies from zero to the max value, a common milling process feature. The proposed approach simulates the process parameters through thread turning or incomplete circular groove turning of workpieces attached offcenter to a lathe tooling. The proposed turn milling simulation method has reduced the number of machined referenced parts by 710 times. Accordingly, the experimental research period and cost have also been reduced. The research has revealed that the VK6M hard alloy tool life in turn milling with coolant is 50 times longer than the R6M5 HSS tool life while the useful tool life (measured as the number of parts machined within the tool life) for VK6M tools in turn milling with coolant is 50 times higher than that of R6M5 HSS tools. 12. Yan Weilin, Fang Liang, Zheng Zhanguang et al. Effect of surface nanocrystallization on abrasive wear properties in Hadfield steel. Tribology International. 2009. Vol. 42 (5). pp. 634-641. 13. Yan Weilin, Fang Liang, Sun Kun et al. Effect of surface work hardening on wear behavior of Hadfield steel. Materials Science and Engineering A. 2007. 460-461 (4). pp. 542-549. 14. Kolokoltsev V. M., Vdovin K. N., Gorlenko D. A. et al. Calculation of stacking fault energy and its influence on abrasive wear resistance of Hadfield cast steel cooled at different rates. CIS Iron and Steel Review. 2016. Vol. 11. pp. 35-40. 15. Ali Nasajpour, Amir Hossein Kokabi, Parviz Davami et al. Effect of molybdenum on mechanical and abrasive wear properties of coating of as-weld Hadfield steel with flux-cored gas tungsten arc welding.

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Aspects of formation of a hobs cutting part for processing of gear wheels are considered. In the traditional manufacture of hobs for processing the rear surfaces of cutting teeth, the process of radial or oblique relieving is used, which due to its dynamic nature associated with reciprocating motions of a grinding head with a grinding wheel installed thereon, makes it difficult to ensure high accuracy of teeth pitch and profile, as well as main hob parameters. These shortcomings are effectively eliminated by using the process of screw relieving to process the lateral rear surfaces of the hob teeth. Execution of a hob teeth profi le in the form of a gear rack enables to obtain a hob for processing gear wheels. A number of formulas are given, by means of which it is reasonably proved that hobs made using the considered principle of formation of teeth back surfaces can have a high class of accuracy — AA or AAA. Calculations showed that the displacement of the hob teeth at two revolutions of the main worm screw with a probability of 0.9973 does not exceed 0.13 μm, which is signifi cantly higher than the requirements of GOST 10331-81 for hobs with AAA accuracy class (not more than 4 μm for hobs with a pitch over 0.5 to 0.9 mm). The considered method of forming the hob rear surfaces in the form of counter right and left multi-turn screw surfaces (screw relieving) allows to obtain hobs not only for machining involute gears, but also other types of cutters, e.g. for machining threads, ratchet wheels and other parts having a regular profile.