In this paper, roughness characteristics as Ra and Rz are observed and their changes regarding to different tool rotation speed without feed, using carbide tool in process of hard machining. By experiments it is shown that, with higher tool revolutions and cutting speed, turning with helical cutting edge yields higher surface quality. Furthermore, during experiments it was proved that it is possible to use carbide tools in hard machining. Results of this paper show that rotational turning has a high potential to become an efficient alternative to hard turning, especially when it comes to large scale production of simple shaped parts.

To generally improve effectivity of parts production and metal cutting process, there are used process models of super alloys together with finite element modeling simulations. Advanced measurement methods of the process could improve and verify the accuracy of these models. These methods cause many error sources when using empiric or exact methods such as infrared radiation thermography to measure the temperature distribution of the tool, workpiece, and chip during metal cutting. Measuring of metal machining is challenging due to factors such as the high magnification required, high surface speeds and deformations, micro-blackbody effects, changing emissivity and deformations present at metal cutting. As part of an ongoing effort to improve our understanding of uncertainties associated with these measurement methods, multimeasurement sets of experiments were performed. First set of measurements observed connection between surface temperature and the internal temperature of the cutting tool. This was accomplished by measuring the temperature using a thermal camera in cutting zone. Second set performed high-speed scan of dynamic processes such as formation of elastic and plastic deformation. During this operation was applied high-speed scannning system using macro conversion lens for monitoring of micro-structural changes in deformation areas. Next necessary applied set is recording of dynamic processes by implementation of piezoelectric measurement device for monitoring of cutting forces. The outputs from multimeasuring system are the basis for verification of theoretical knowledge from this field and elimination of uncertainties, which arise by using computer simulation systems.

Abstract:Objective:Titanium and titanium alloys represent generally accepted metallic biomaterials for clinical dentistry and dental implantology. In th is paper, we present a Ti-35.5Nb-5.7Ta alloy with a special respect to its microstructure and mechanical characteristics, such as Young modulus of elasticity. Methods:Three thermal treatments differing in temperature and time of annealing were used during the Ti-35.5Nb-5.7Ta processing in order to evaluate the effects of ageing, melting annealing, and annealing on mechanical characteristics and microstructure. Results: Using microscopy, the alloy was analyzed and the differences in shares of beta phase grains, alpha particles and precipitates evaluated. The three thermal treatments were evaluated also from technological point of view. Conclusion:The following thermal treatment was found optimal for the Ti-35.5Nb-5.7Ta alloy: melting annealing at 800 °C for 0.5 hour followed by a cold swaging with a 52-79 % deformation, and fi nal hardening at 500 °C for 2 hours in water (Tab. 2, Fig. 3, Ref. 24).Text in PDF www.elis.sk.

Residual stresses significantly affect the life of parts material, especially in bearing manufacturing, where the stress introduced into the material in the manufacturing process affect the component throughout its whole operating life. It is therefore important to know the size and orientation of these stresses and to optimize the production process of the bearing rings, in order to eliminate as many of these undesirable stresses. The subject of the article is chosen at demand of practice and has to correlate coating cutting tool for residual stress and microstructure in turning the outer bearing rings made of material 1.3520, which is widely used in bearing production. Turning cutting tool WNMG 080408E-M was used with two different coatings. We conducted measurements on a X-ray diffractometer. We measured normal stress parameter and the FWHM (full width half maximum at), which is decisive, and it is related to the grain size of the material. We found that the residual axial stress approaching the zero value, depending on the etched layer.

The article deals with drilling of titanium alloys, which are becoming more widely used in aerospace and automotive industry as well as in other sectors for its specific properties such as hardness, corrosion resistance, biocompatibility, etc. The aim of this article is basic research with focus on drilling conditions of titanium alloy using HSS drill bits with diameter ø2,3 mm with PVD coating and without coating on CNC turning machine Polygim Diamond 12 series. This research can support problem solutions in small diameter drilling.