Modeling the Effect of Cutting Fluids in Peripheral Milling

Ge Shen | PhD | 2003

Abstract:

Cutting fluids have been widely employed in machining applications for many years. The primary functions of cutting fluids in machining operations are removal of heat and lubrication. Similar to other machining processes, cutting fluids are often used in peripheral milling operations. Most often performed with end mill type cutters, the peripheral milling process is one of the most commonly used machining operations in industry. The present research is focused on the role of cutting fluids in peripheral milling includes two fundamental issues: effects of cutting fluids on the cutting forces produced in the milling process, and effects of cutting fluids on the temperature of the workpiece being produced by a milling operation. These two issues are addressed through the development of mechanistic models and the validation of these models through experimental efforts.

As a first step, in order to study the effect of cutting fluids on cutting forces (tangential force and radial force), a model is developed for the cutting forces in peripheral milling. The cutting force model is then applied to a situation where a roughing cutter is used in an end milling process. The primary difference between a roughing endmill and a conventional endmill is in the geometry of the individual cutting edges. The dynamic cutting force prediction model for a roughing cutter have a roughing endmill geometry model, a dynamic force model and a flank face interference model. This cutting force model for a roughing endmill is validated experimentally.

A modeling work is presented to predict the temperature distribution in a workpiece being milled by a straight fluted cutter. Such temperature information is important in assessing the thermal distortion produced in the process. At first, the cutting forces and heat energy generated in the milling process are predicted. The heat generated during cutting is transferred into chips, the cutting tool, and the workpiece. Thus, heat partition models are developed to calculate the thermal energy that goes into the workpiece. These heat partition models include prediction of the heat fraction from the shear plane into the workpiece near the shear plane, and computation of the heat partition from the chip/workpiece interface into the final machined workpiece. The first heat fraction is obtained through calculating the temperature distribution on the shear plane and the heat flux from the shear plane. The second heat fraction is achieved by solving a two-dimension, steady-state, homogeneous boundary value problem of heat conduction with constant coefficients and a uniform heat source at one end of a semi-infinite strip domain. Finally a workpiece temperature prediction model is developed to compute the temperature distribution in a three dimensional finite rectangular workpiece by solving a 3-D, time-dependent, nonhomogeneous boundary value problem of heat-conduction with temperature-independent properties and with a moving line heat source through the integral transform technique. This heat transfer model is experimentally validated, and the effect of cutting fluids on the temperature of the workpiece is investigated.

Finally this research work is summarized, and conclusions are presented. Some recommendations are given for future work that can be done in this area.

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