Effects of Drilling Induced Defects and Mechanical Properties of GFRE Composites

Glass fiber reinforced epoxy composites become highly demanded on the way to
producing parts in various industry uses for example in aerospace and oil and gas fields.
Drilling of fiber composites is one type of machining that mostly applied for assembly
uses and it can be problematic especially at the drilled holes. Damages occurred at the
drilled holes could lead to adverse impact on its functions. The condition of fiber
composite which is in homogeneity of the materials per part is one main cause that makes
drilling of fiber composite becoming troubles. In this study, GFRE composite was
developed using wet hand lay-up technique with 40% fiber volume fraction of woven
glass fiber. 9 samples were prepared with geometry from standard ASTM D3039 was
referred and each sample was tested by different parameters. Parameters studied are
narrowed to focus on the feed rate (0.05 mm/rev, 0.1 mm/rev, and 0.2 mm/rev) and
spindle speed (1000, 2000 and 3000 rpm) of drilling process using 10 mm HSS drill bit
for each cutting parameter on MTAB Denford CNC Milling Trainer XLMILL machine.
Drilled samples were analyzed on its holes in term of damage factor using 3D Noncontact
Measuring Machine where delamination of plies ratio with drill bit diameter
around the drilled holes was measured. Tensile strength of drilled samples were also been
obtained in this study by using Universal Testing Machine and 100 kN of load was
applied to find the correlation between damage factor to the tensile strength of each
samples. Best result for damage factor was obtained on sample F (0.1mm/rev, 3000 rpm)
and it also showed highest tensile strength rather than others. From the results obtained, it
can be related that increasing of damage factor will lead to minimal value of tensile
strength.