Waviness at dry high-speed face milling of some hard steels

Waviness is a parameter used to complete information on the machined surface state. There is little scientific and technical information on the influence exerted by the cutting conditions and the workpiece material hardness on the values of some parameters that define the waviness of milled surface. No works have been identified to present such information for dry high-speed face milling applied to hard steel workpieces. A factorial experiment with four independent variables at three variation levels was planned to model the influence of milling speed, feed, cutting depth, and steel hardness on the total heights of the profile and surface waviness for dry high-speed face milling. Mathematical processing of experimental results was used to identify the power type function and empirical mathematical models. These models highlight the direction of variation and the intensity of influence exerted by the considered input factors on the values of two waviness parameters in the case of dry high-speed face milling of samples made of four hard steels. It has been observed that the increase in steel hardness increases the total heights of the profile and surface waviness. In the case of two types of steel, a good correlation was identified between the values of the total profile waviness height and the total surface waviness height, respectively, using the Pearson correlation coefficient

Theoretical considerations concerning the profile error of the thread flank

In the case of metric thread, a possible source of the flank error could be the position of the cutting tool edge, which could not intersect the circular cylindrical surface axis. An analytical method of approximation was applied to model the way in which the flank error is generated by considering some geometrical conditions. A theoretical simplified model was determined to highlight the influence of the thread external diameter and of the distance between the circular cylindrical surface axis and the thread rectilinear generatrix on the profile error of thread flank

Theoretical considerations concerning the profile error of the thread flank

In the case of metric thread, a possible source of the flank error could be the position of the cutting tool edge, which could not intersect the circular cylindrical surface axis. An analytical method of approximation was applied to model the way in which the flank error is generated by considering some geometrical conditions. A theoretical simplified model was determined to highlight the influence of the thread external diameter and of the distance between the circular cylindrical surface axis and the thread rectilinear generatrix on the profile error of thread flank

Locating Error when Clamping Workpiece between Centers

The total machining error includes some distinct errors summed up by following certain rules. One of these errors is the workpiece locating error, which occurs when the workpiece reference base does not match the workpiece locating surface. The paper analyses different definitions of positioning error, as they were proposed by different researchers or groups of researchers and presents an application valid in the case of turning a cylindrical workpiece with locating between the centers. A definition of locating error that takes into account the total differential of the size of the vector that joins the orientation surface with an element of the fixture was preferred. A fixture version was considered to ensure the locating and clamping of the workpiece on the lathes, with workpiece locating between the centers. This fixture uses a mandrel with a sliding center and an elastic collet