INFLUENCE OF MANUFACTURING PROCESS AND FIBER VOLUME ON EDGE FINISHING CHARACTERISTICS AND SURFACE INTEGRITY OF GLASS FIBER REINFORCED PLASTIC COMPOSITES

摘要

Orthogonal trimming characteristics were evaluated on two Glass Fiber Reinforced Plastics (GFRPs) manufactured by preform and Sheet Molding Compound (SMC) processing techniques. Cutting parameters included cutting speed and depth of cut. Tool materials used were carbide and Polycrystalline Diamond (PCD) tools. Experiments were conducted with GFRPs with different primary processing techniques and volume fraction of reinforcing fibers. Machining characteristics of GFRPs were evaluated in terms of cutting forces, surface quality, and tool wear. As a result of this evaluation, the depth of cut has the largest influence on cutting forces. Cutting forces were generally found to increase with both material removal rate and reinforcing fiber contents. It was also found that PCD tools performed better than carbide tools in terms of minimal cutting forces, surface quality, edge delamination and fiber protrusion but the grinding process produced minimum damage with moderate surface finish. Surface integrity was evaluated in terms of surface roughness, tensile and fatigue strengths. The preform materials were much less variable in their stress vs. strain behavior to failure in Ultimate Tensile Strength (UTS) as compared to the SMC materials. This may be attributed to the manufacturing process difference in these materials, with preform compression molding providing a more random fiber distribution over the material plaques used. Results also show that fiber volume and surface finish have a significant effect on the fatigue performance of composite materials.