Machining of composite materials can be a tricky undertaking.  Delamination of the reinforcement in the composite material is one of the biggest problem.

There are several steps that can be taken.  Specially-designed drills and cutting blades can be used to help eliminate delamination.  These tools generally need to be sharper and turn faster than working with materials that are made of metal.  The cutting tools generally need to be hard, and diamond-coatings assist in making these operations easier.

Water jet cutting is another good way to cut composites materials.  This process uses high-pressure water that contains abrasives to cut into materials and provide high-tolerance work.