Regular Surface Texture Generated by Special Grinding Process

Abstract

Most of the methods for generating regular surface texture (RST) consist of shaping a set of regular grooves (cavities) arranged in a regular way. This paper presents possibilities for regular surface texture generation by so-called “pattern grinding” with the wheel prepared in a special way. The simple variant of the method involves grinding with the wheel having helical grooves. The grooves shaped on the work material are the result of specific wheel surface reproduction. The ratio between work-material feed and wheel speed is an important factor, determining the layout of the grooves generated on the work-material and the shape of the groove sides. Surface texture consists of two components: deterministic, resulting from the nominal wheel active surface, and random, resulting from the random shape and arrangement of abrasive grains. The limited contribution of the random component of surface texture is discussed based on the ratio between the undeformed chip thickness and the sizes of the grooves. Kinematical analysis of the wheel reproduction process is performed for description of nominal surface texture. Experimental results of flat and cylindrical surfaces, obtained with pattern grinding are also provided. Two critical values of the ratio between work-material feed and wheel speed were derived, and three ranges of this ratio are discussed. The kinematical approach provided relationships between input data of the process (wheel shape and grinding parameters) and nominal groove dimensions and groove layout. The geometrical characteristics of the work-material nominal surface texture are presented for each of the three types of surface texture. It is important to ensure that the work feeds are greater than the lower critical value. For achievable work feeds the shape of the sides of the grooves is cycloid. Experiments revealed the limited contribution of the random component of the surface structure of the work material. Random arrangement of abrasive grains is important only at local (micro-) level and affects the roughness of groove bottoms, while the dimensions and arrangement of the grooves are affected only to a minimal degree.