The vibration during external cylindrical grinding is caused by many factors such as the rigidity of the technology system, machining modes, machining materials, cooling mode, etc. This paper employed a Taguchi method to design experiments and evaluate the influence of machining mode parameters and workpiece material hardness on the vibrations when machining some types of alloy steel in external cylindrical grinding process. The influence of machining conditions on the vibrations was investigated. Besides, the mathematical models of vibration amplitudes were also modeled. The achieved results can be used to control the vibrations through machining conditions to improve the surface quality of the product.

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Screw air compressors have been being used widely for 45 years. There are many research works on these machines, but there have been still many problems, especially on designing and machining their screw pair, to study. This paper focuses on gate screw profiling from the main screw profile and disc tool profiling for manufacturing the screw pair. The air compressor screw 3D model pair, designed by using the proposed methods, have satisfied the meshing condition. The disc tool 3D models created for machining the screws have also been tested in many ways, these testing results show high accuracy of the disk tool 3D model, which can be used in industrial manufacturing.

In this study, by performing the experimental research, the surface roughness, cutting force and vibration were modeled. The Genetic Algorithms (GAs) were applied to determine the optimal values of external cylindrical grinding conditions to achieve the minimum value of surface roughness and the maximum value of the material removal rate. The optimum values of surface roughness and material removal rate are 0.490 [Formula: see text]m and 3.974 mm2/s, respectively, that were obtained at a feed rate of 0.3 m/min, at a workpiece speed of 164.82 rpm, at a cutting depth of 0.015 mm, and a workpiece Rockwell hardness of 56.32 HRC. The optimal values were successfully verified by experimental results with very promising results.

One of the best practical methods to machine the air compressor screw pairs is milling or grinding by disc tools. The mathematics involved in disc tool profiling is quite complex and requires representing the machined surface by mathematical equations without any singular points and undercutting. From a technical perspective, this article proposes the disc tool profiling integrated solution for machining complex profile screws from their reverse engineering data, which contains crucial issues such as machining deviation evaluation due to undercutting, appropriate tool position setting. The disc tool surface designed by the proposed method is highly accurate, leading the RMS error of the machined surface is less than 0.0201 mm. A difference of the angle, formed by the disc tool axis and the workpiece axis, less than 0.16°, is acceptable in air compressor technology, which leads to a machined surface RMS deviation of less than 0.0186 mm.