Click Image to Enlarge Here is an example of a drill designed
specifically for composites. The patented point design shown
here reduces delamination, splintering and fraying by reducing
pressure on the material and reducing thrust and torque to
improve cutting efficiency. The reduction in forces has the
additional benefit of reducing the heat generated in the cutting
area. Photos courtesy of Precision Dormer. General Tool uses a
drill such as this one to machine holes in composites undersize,
then completes the hole through circular milling to ensure that
exit quality meets the customer’s requirements. Drilling tends
to be the real challenge of machining composite parts. A drill
cutting through a metal part simply has to remove the material
and clear the hole. By contrast, a drill cutting through a
layered composite structure is likely to push the layers ahead
of it, producing unacceptable delamination on the exit side.
Earl Wilkerson is CNC programming and tooling supervisor for
General Tool, a 240-employee