Experimental Study On Surface Quality And Micro Burr Formation In Micro-milling

Microcutting is becoming an important microfabrication technology due to the increasing demand for micro parts. In contrast to conventional machining,it has some unique aspects. The main difference between them is the generation of size effect in microcutting. Noticable size effect, minimum chip thickness and ploughing effect are observed in the microcutting processes when the uncut chip thickness decreases down to micro scale. It is necessary to understand the deformation mechanics in the microcutting. The main objective of this study is micromilling, which is an emerging technology and has the ability to fabricate miniature parts with complex three-dimensional shapes in a wide range of materials.In reality cutting tools are never sharp but have a finite edge radius along the cutting edge. The machined surface quality is influenced by tool edge radius while the surface roughness is closely related to the feed rate. In this study, the influence of cutting tool edge radius and the ratio of the feed rate to cutting edge radius on machined surface roughness, surface topography and micro burr formation in microcutting are studied by using theoretical analysis and experimental study.Cutting parameters and the properties of workpiece material are the major factors in affecting the surface integrity. Micro-milling experiments are conducted by using two different tool tip diameter end milling tools. The workpiece materials are45#steel and A17050-T7451. The machined surfaces with different cutting conditions are analyzed in terms of surface roughness and surface topography. The experimental result shows a critical value of feed rate per tooth that yields the lowest surface roughness. Material microstructure has a significant effect on microcutting processes. A theoretical model is proposed to predict the surface roughness by considering feed rate per tooth and tool tip diameter.The surface quality is significantly influenced by the burr formation in micro-milling process. The effects of feed rate per tooth, tool tip diameter and the ratio of feed per tooth to cutting edge radius on burr formation in micromilling are studied by experiments. This paper investigates the mechanism of the top burr formation on the feed direction in micro-milling slots. Burr formation is also affected strongly by the wear of tool. In order to minimize burr formation, experiments were conducted to find the optimal combination of machining parameters and tool tip diameter.The findings of this study can be used to improve microcutting processes, and provided a theoretical foundation for designing micromilling tools.