THE INFLUENCES OF VARYING FEED RATE ON HOLE QUALITY AND FORCE IN DRILLING CFRP COMPOSITE

Year 2017, Volume: 30 Issue: 3, 39 - 50, 20.09.2017

Nafiz Yaşar , Mustafa Günay

Abstract

The selection of drill geometry and
drilling parameters has high importance due to thermo-mechanical formations in
drilling of carbon fiber reinforced polymer (CFRP) which has anisotropic
structure. This study focused on the effects of drilling parameters on thrust
force and hole quality in drilling of CFRP composites by applying constant and varying
feed rate with uncoated WC drills having different point angles. Surface
roughness, delamination factor and diameter plays a crucial role in the
production of close-tolerance holes in hole quality. The quality of the hole
surface was examined via surface roughness measurements and surface damage by
scanning electron microscopy (SEM). Machinability experiments were performed
with three different levels of drilling parameters that are point angle,
cutting speed and feed rate. It was determined that thrust force (Fz),
delamination factor (Fd) and surface roughness (Ra) values obtained in drilling
processes by varying feed rate in hole exit are lower than that of constant
feed rate with average of 21%, 14% and 36%, respectively. On the other hand,
hole diameter (d) values obtained with varying feed rate in hole exit were higher
than that of constant feed rate. The effects of drilling parameters on Fz, Fd
and Ra were determined by analysis of variance with 95% confidence level and
feed rate was found as the most significant parameter on them.

Keywords

CFRP, Drilling, Varying feed rate, Hole quality, Anova

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