Grinding of Helical Surfaces on End Mills: Monitoring by Means of Optimal Tolerances

The performance of end mills depends on the accuracy in manufacturing their helical surfaces. Preparations for this process involve determining the position and orientation of the grinding wheel. On account of setup errors and the low rigidity of the system, each machined profile of the helical surface will differ from the ideal. The quality of surface machining plays an important role. Each machined profile of the helical surface will have various deviations from the ideal form; the extent of such deviation may be critical to tool performance. Available methods of monitoring surfaces of complex form with a uniform distribution of the tolerance are of no value for end mills, since, with a particular value of the tolerance, too many profiles with an incorrect rake surface may be accepted or else profiles with back deviation may be wrongly rejected if setting uniform tolerances with respect to the rake surface results in requirements on the channel back that are too strict. Therefore, in the present work, new recommendations for monitoring the quality of multicoordinate grinding in the helical channels of end mills are proposed, along with a corresponding procedure. The quality of machining is assessed from the deviation of the geometric parameters (the core diameter, the profile angle, and the rake angle), as well as the roughness of the machined surface. This method is universal: it may be employed to monitor the accuracy of the profile for three-, four-, and five-tooth mills used in machining steel, aluminum, cast iron, and other structural materials.