Surface roughness of fiber reinforced plastic laminates fabricated using rubber pressure molding technique

Abstract The rubber pressure molding (RPM) technique for fabricating fiber reinforced plastic (FRP) laminates is a new development in manufacturing technology of FRP composites. The technique is based on the matching die set, where the die is made of hard metal like steel and the punch from the flexible rubber‐like material, natural rubber (NR). A split steel die and rubber punch are designed and fabricated to prepare the FRP product. The same split die is also used to cast the rubber punch. The use of flexible rubber punch applies hydrostatic pressure on the surface of the product. The rubber used to make the punch for pressing the component during curing process contains carbon black as filler material. The present study was carried out to investigate the effect of carbon black loading on the surface roughness of the FRP components produced by RPM technique. Natural rubber with different loading of carbon black (0 to 120 phr) was used for making the punch to fabricate the laminates through RPM technique. A number of FRP laminates with polyester resin and glass fiber were prepared to perform the experimentation. It was observed that as the loading of carbon black in rubber punch is increased from 0 to 120 phr, there is a significant decrease in the surface roughness of laminates. The surface roughness values of FRP laminates are correlated with a proposed model. POLYM. COMPOS. 27:504–512, 2006. © 2006 Society of Plastics Engineers