Influence of Grinding Atmosphere on Grinding Characteristics of CFRP (Effect of Soluble Coolant or Liquid Nitrogen Supply)

Abstract

CFRP (Carbon Fiber Reinforced Plastics), which is increasingly applied to airplanes, automobiles, production equipment for electronic device, and so on, is machined after molding process. Grinding is often used for edge finishing of CFRP parts. This paper deals with the influence of grinding atmosphere on grinding characteristics of CFRP by the experimental investigation of ground surface characteristics, surface finish, grinding force, grinding temperature, etc. in surface grinding of unidirectional CFRP using a vitrified bond diamond wheel with the water soluble coolant and the liquid nitrogen in addition to dry grinding. The grinding temperature has been measured by a developed thermocouple system using carbon fibers being made up CFRP and a constantan wire setting between CFRP specimens. The grinding temperature at wheel contact area on CFRP is higher than the glass-transition temperature of CFRP at larger setting wheel depth of cut. The wet grinding prevents in worsening ground surface of CFRP and increasing grinding force that occur in dry grinding of CFRP. The liquid nitrogen makes some effect on prevention in wheel loading and delamination of carbon fibers in dry grinding of CFRP, however the grinding force supplying liquid nitrogen becomes larger than that in dry grinding because of an increase in hardness of CFRP by freeze up. The bending strength of ground CFRP, which suggests the scale of affected layer, is improved by supplying the water soluble coolant and the liquid nitrogen in grinding process.