Browsing by Subject "Force modeling"

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Open Access
Mechanistic force modeling for milling of carbon fiber reinforced polymers with double helix tools
(Elsevier, 2013) Karpat, Y.; Polat, N.
Carbon fiber reinforced polymers (CFRP) have emerged as the material of choice to satisfy increasing demand for lighter aircrafts. Machinability characteristics of CFRPs are quite different than those of metals; therefore, special tool designs have been developed for CFRP machining. The double helix end mill design compresses the upper and lower sides of the laminate using opposite helix angles that eliminate delamination. A mechanistic force model for double helix tools is developed based on milling force data obtained on flat end mills. The proposed model can be used to improve double helix tool designs and to optimize milling process parameters.
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.