Browsing by Subject "Polycrystalline diamond (PCD)"

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    A hybrid model to analyze stress distributions at the tool and workpiece interface during drilling of thick CFRP laminates
    (2024-08) Shariar, Fahim
    Drilling is employed as a machining method to meet the demands for producing functional CFRP structures without compromising their unique and desirable material properties. Because of its temperature-dependent properties and drillinduced damages, drilling CFRP remains an ambitious task. This study proposes an analytical drilling model coupled with a finite element-based thermal model to predict the characteristic time point-based thrust force and torque generated during the drilling operation. A better understanding of pressure and tangential stress distribution along the drilling cutting edge is necessary to select process parameters better. The drill margin region, which directly affects the hole wall quality, has also been included in the analysis. Drilling experiments were conducted to measure thrust force, torque, and temperature for five different configurations of feeds and spindle speeds. The workpiece FE model utilizes a Gaussian distributed ring-type heat flux, and the tool uses characteristic time point-based step functions as heat fluxes to emulate the drill’s progress through the CFRP laminate. The finite element-based thermal models have been considered to evaluate the heat partition during the drilling operation and estimate the subsequent temperature profiles on the drill tip and hole wall surface, respectively. The hybrid analytical and computational model has been used to analyze the variation of peak pressure and tangential stress distributions on the tip of the drill as well as the thermomechanical response of CFRP based on experimental measurements of thrust force, torque, and temperature and investigation of the condition of the holes for various drilling configurations.
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    ItemOpen Access
    Tool geometry based prediction of critical thrust force while drilling carbon fiber reinforced polymers
    (Shanghai University Press, 2015) Karpat, Y.; Bahtiyar O.
    Carbon fiber reinforced polymers (CFRPs) are known to be difficult to cut due to the abrasive nature of carbon fibers and the low thermal conductivity of the polymer matrix. Polycrystalline diamond (PCD) drills are commonly employed in CFRP drilling to satisfy hole quality conditions with an acceptable tool life. Drill geometry is known to be influential on the hole quality and productivity of the process. Considering the variety of CFRP laminates and available PCD drills on the market, selecting the suitable drill design and process parameters for the CFRP material being machined is usually performed through trial and error. In this study, machining performances of four different PCD drills are investigated. A mechanistic model of drilling is used to reveal trade-offs in drill designs and it is shown that it can be used to select suitable feed rate for a given CFRP drilling process. © 2015, Shanghai University and Springer-Verlag Berlin Heidelberg.