How to choose the abrasive grain size in abrasive belt grinding

Grain size selection is one of the key factors that determine the processing effect. In general, the choice of granularity considers the following aspects.

(1) The machining allowance of the workpiece is large, and the coarse grinding grain size should be selected if the grinding efficiency is high. Otherwise, the fine particle size should be selected. In general, when machining similar parts, the grinding efficiency of the belt is higher than that of the grinding wheel, because almost all of the abrasive grains arranged in the surface of the belt can be ground, and the abrasive grains are embedded on the surface of the workpiece. The depth is larger than the grinding wheel, so when the surface roughness of the workpiece is the same, the abrasive grain size of the abrasive belt should be finer than the abrasive grain size of the grinding wheel. For example, the grinding wheel surface grinder uses 36#~46#, and the abrasive belt uses 46#~60# grain size. For example, the external grinding machine uses a grinding wheel with a size of 60#~80#, and the belt with an abrasive belt is made of 80#~100#. Of course, the choice of particle size should also be combined with the rigidity and operational skills of the grinding machine.

(2) In the case where the workpiece roughness requirements are the same, the fine line speed of the belt is high, and the coarse grain size is preferred. For example, the surface light speed of the plywood is 15~20m\s, the particle size of the abrasive is 36#~46#, and when the wide belt sander is used, the line speed of the belt is 32m\s, and the abrasive grain size is 60#.

(3) When processing metal materials and non-metal materials, if the surface quality requirements are similar, the metal workpieces are processed with fine grain size, and the non-metal workpieces are processed with coarse grain size.

4) When processing the same kind of workpiece, the coarse grinding grain is used for the dry grinding process; the fine grain size is used for the wet processing, and if the lubricating oil is used as the coolant, the finer particle size is selected.

(5) When the belt contact grinding area is large, the coarse grain size should be selected; the contact area is small and the fine particle size is used. For example, the contact surface of the plane grinding is generally larger than the contact surface of the outer cylindrical grinding. Therefore, when processing the workpiece of the same material, the grain size of the surface frosted belt should be slightly thicker than the outer grinding belt.

(6) Select the grain size according to the material of the machined workpiece. When processing a metal with high toughness or soft performance, the sand belt is easily blocked, so it is preferable to use a coarse grain size; when processing a steel having a large hardness, a fine grain size may be selected.