A review of mechanical drilling for composite laminates

The path towards delamination-free drilling of composite materials

An experimental study of orthogonal cutting mechanisms was conducted in the edge trimming of unidirectional Graphite/Epoxy composite with polycrystalline diamond tools. The effects of tool geometry and operating conditions were evaluated from an analysis of chip formation, cutting force and machined surface topography. All aspects of material removal were found to be primarily dependent on the fibre orientation. Discontinuous chip formation was noted throughout this study, regardless of trimming parameters. Chip dimensions and force measurements depicted a change in chip formation with fibre orientation, and the presence of three distinct mechanisms in the edge trimming of fiber reinforced composite material. A combination of cutting, shearing and fracture along the fibre/matrix interface was observed.

Orthogonal cutting mechanisms of graphite/epoxy composite. Part II: multi-directional laminate

A review on machinability of carbon fiber reinforced polymer (CFRP) and glass fiber reinforced polymer (GFRP) composite materials

The effects of hole machining defects on strength and fatigue life of carbon/epoxy laminates subjected to static and fatigue loading are presented. Dry specimens were subjected to pin loading and uniaxial compressive loading at room temperature. The KTH method, a new method which gives defect-free holes, was used to machine holes in the specimens. For comparison, holes were also machined using two traditional drilling techniques causing varying extents of damage. X-ray techniques were used to detect the hole machining defects. The permanent deflection of compressively loaded specimens was monitored during cyclic loading. Hole machining defects significantly reduced the static and fatigue strengths of pin-loaded laminates; the effects on the strengths of compressively loaded laminates were less pronounced.

D.A. Walton

Papers

Machining of composite materials. Part I : Traditional methods

Machining of composite materials. Part II: Non-traditional methods