SCIENCE AND TECHNOLOGY ENGLIAH FOR MECHANICAL ENGINEERING The disad vantage of a coarse feed rate is that a clear marking is left on the workpiece, particularly in the root showing a pattern at a spacing of the feed rate per revolution. This surface undulation is less marked on the 波 fianks than in the root and is not important when there is a 'x subsequent finishing operation such as shaving or grinding. 剃 When there are no further operations the feed per revolution 齿 must be restricted to keep the undulations below a limit which is usually dictated by lubrication conditions. The height of the undulations in the root of the gear is given by quaring the feed per revolution and dividing by four times he diameter of the hob.I mm feed and 100 mm diameter gives 2. 5 micron high undulations in the root. On the gear flank (at 70 on a large gear) the undulation is roughly cos 70o as large, 1. e, about 0.85 micronSCIENCE AND TECHNOLOGY ENGLISH FOR MECHANICAL ENGINEERING The disadvantage of a coarse feed rate is that a clear marking is left on the workpiece, particularly in the root, showing a pattern at a spacing of the feed rate per revolution. This surface undulation is less marked on the flanks than in the root and is not important when there is a subsequent finishing operation such as shaving or grinding. When there are no further operations the feed per revolution must be restricted to keep the undulations below a limit, which is usually dictated by lubrication conditions. The height of the undulations in the root of the gear is given by squaring the feed per revolution and dividing by four times the diameter of the hob, l mm feed and 100 mm diameter gives 2.5 micron high undulations in the root. On the gear flank (at 70ºon a large gear) the undulation is roughly cos 70ºas large, i.e., about 0.85 micron. 波 纹 剃 齿