1. Delamination by drilling

The assembly of a composite element on a structure often requires the creation of holes to receive bolts or rivets. A variety of processes are used to produce the holes. These include molding and machining (using a cutting tool or abrasive water jet).

Molded hole drilling involves inserting a metal rod to spread the fibers apart during the draping operation (cleanroom manufacturing). This results in local disruption of fiber orientation, particularly at the edge of the hole.

Machined drilling involves cutting the laminate fibers. This process weakens the composite structure