Micromilling Process Planning and Modeling for Micromold Manufacturing

In this paper, a model-based micro-end milling process planning guideline for machining micro mold cavities was proposed. The goal is to facilitate proper selections of the process parameters. Specifically, the axial depth of cut, the feed per tooth are critical in achieving performance objectives in terms of cutting forces, surface accuracy, tool life, etc. To this end, the finite element modeling was used to provide a comprehensive understanding of the underlying science base for the micro-machining (e.g., chip formation mechanisms, minimum chip thickness effect, material deformation flows, stress, strain and temperature distributions). Further, a mechanistic time-domain simulation model was utilized to provide predictive capability in practical machining performance, such as cutting forces, tool vibrations, surface accuracy, 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. The proposed process planning strategy was applied for micro-milling of a mold cavity in AL2024-T6.