Investigations on Mechanics-Based Process Planning of Micro-End Milling in Machining Mold Cavities

This article may be used for research, teaching and private study purposes. Any substantial or systematic reproduction, redistribution , reselling , loan or sub-licensing, systematic supply or distribution in any form to anyone is expressly forbidden. The publisher does not give any warranty express or implied or make any representation that the contents will be complete or accurate or up to date. The accuracy of any instructions, formulae and drug doses should be independently verified with primary sources. The publisher shall not be liable for any loss, actions, claims, proceedings, demand or costs or damages whatsoever or howsoever caused arising directly or indirectly in connection with or arising out of the use of this material. In this article, a model-based micro-end milling process planning for machining micromold cavities is proposed. The goal is to facilitate proper selections of the process parameters for a given workpiece material, cavity geometry, and micro-end mill. Specifically, the axial depth of cut and the feed per tooth are critical in achieving performance objectives in terms of low cutting forces and high surface accuracy and material removal rate. An analytical model based on process mechanics is used to select feed per tooth range in micromilling to avoid size effects. Further, a time-domain simulation model is utilized to provide predictive capability in practical micromachining performance, such as cutting forces, surface form, and surface roughness. The generalized process planning strategy consists of two steps: roughing and finishing. In roughing, the objective is to control the cutting force within a predefined threshold to prevent premature tool breakage and to maximize the material removal rate. In finishing, the primary objective is to control the form error within the tolerance and to obtain satisfactory surface roughness. 1. Introduction With the growing importance of product miniaturization and the ever-increasing popularity of micro-end milling operation in fabricating miniature components, significant amount of research have been undertaken to gain a better understanding of the micro-end milling process [1]. Although process kinematics do not change, the cutting and surface generation mechanisms involved in the micro-end milling process change dramatically as the process scales down from macro to microscale. These changes are mostly due to the different cutting mechanics induced by the tool-workpiece engagement, cutting geometry, and scaling relationship between the micro-end milling tool (flexural strength, tool edge geometry, and tool material grain size) and workpiece material microstructure. In micromechanical machining, due to limited strength of …