Effect of Additives on the Machinability of Glass Fiber Reinforced Polymer

Glass fiber reinforced polymers (GFRP) are composite materials widely used in all fields of applications. Once cured to near net shape, GFRP parts often need several finishing operations such as trimming, milling or drilling in order to meet final dimensions and accommodate fastening hardware. The cutting temperature is crucial when dealing with such finishing operations for synthetic composite materials. Cutting temperatures higher than the glass transition temperature (T_g) of the resin matrix are highly undesirable: they cause degradation of the matrix around the cut edges, which can severely affect the mechanical performance of the entire component. This research aims to study the effect of adding different particles to the epoxy matrix of glass fiber reinforced polymers (GFRP) on the cutting temperature and surface finish for the trimming operation of this material. Five plaques were made, each with a different epoxy mixture: no additive, wetting agent (WA), WA and clay, WA and wax, WA and clay and wax. From the results, it can be concluded that wax particles significantly decrease the cutting temperature for the trimming process. The maximum recorded temperature was found to be 30% lower than for the reference plaque having no additive. Regarding the surface roughness, the wax particles also seem to have a positive effect, with the R_a value decreasing by a value of up to 32% versus the reference material. The synergy between the clay and the wax particles added to epoxy is promising for improving GFRP machining.