Browsing by Subject "Micro-milling"

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Open Access
Identification of internal process parameters of micro milling considering machined surface topography
(2022-07) Masrani, Abdulrzak
Micro-milling is a fast and versatile machining method that can be used to manufacture three-dimensional parts of a wide range of materials with high accuracy. Modeling of micro-milling processes is complex due to size effects, where the chip thickness becomes comparable to the cutting edge radius. Furthermore, tool runout and deflection effects on the process outputs are amplified and cannot be neglected. As the process is scaled down where micrometer accuracy is required; modeling and identifying the process parameters becomes essential to optimize or monitor the process. This study presents a systematic approach to force modeling and parameter identification of micro-milling processes. Finite element analysis of tool deflection is integrated into mechanistic modeling of micro-milling forces together with considering the trochoidal trajectory of the cutting teeth, tool runout, and chip thickness accumulation due to minimum uncut chip thickness. The internal process parameters are identified using the experimental cutting forces and machined surface topography with a novel methodology. The research results are experimentally validated by slot and side micro-milling tests on commercially pure titanium, using coated carbide micro-end-mills with diameters of 0.2 and 0.4 mm, and accurate predictions of model parameters and cutting forces are obtained. The proposed force models can be used in smart manufacturing and digital twin applications to reduce the time and costs associated with process optimization. The proposed parameter identification techniques can also help to reduce the need for advanced measurement systems.
Open Access
Using micro-milled surface topography and force measurements to identify tool runout and mechanistic model coefficients
(Springer UK, 2023-02-15) Masrani, Abdulrzak; Karpat, Yiğit
Modeling the forces during micro-milling processes is directly linked to the chip load and mechanistic model parameters that are generally dependent on the tool/work combination. Tool runout, deflection, and the material’s elastic recovery mainly affect the chip load as a function of feed. Experimentally measured micro-milling forces can be employed to identify cutting force coefficients and runout parameters. However, decoupling the interplay among runout, deflection, and elastic recovery is difficult when only measured forces are considered. In this paper, machined surface topography has been considered as an additional process output to investigate the influence of runout and deflection separately. The machined surface topography was investigated using a scanning laser microscope to identify minimum chip thicknesss and runout parameters. A finite element model of tool deflection has been developed based on the end mill geometry used in the experiments. The finite element model was used to obtain a surrogate model of the tool deflection which was implemented into the mechanistic model. Nanoindentation tests were conducted on the coated WC tool to identify its material properties which are employed in the finite element model. An uncut chip thickness model is constructed by considering preceding trochoidal trajectories of the cutting edge, helix lag, tool runout, tool deflection, and the chip thickness accumulation phenomenon. The force model was validated experimentally by conducting both slot and side milling tests on commercially pure titanium (cp-Ti). The predicted cutting forces were shown to be in good agreement with the experimental cutting forces.