A STUDY OF RIB GEOMETRY FOR GAS-ASSISTED INJECTION-MOLDING

Large, thin plate-shaped parts usually are strengthened with structura l ribs. Ribs also serve as gas channels with gas-assisted technology. The layout and geometry of these gas-channel ribs are critical to the gas-assisted injection molding (GAIM) process. In this study, the effe cts of rib geometry, including aspect ratio and fillet geometry, on th e GAIM process are investigated. Experimental results indicate that in creasing the rib width widens the allowable operation range and thus i mproves the moldability. Adding fillets to the rib corner significantl y enhances the moldability. Adding fillets also reduces the loss of ri gidity due to void formation in the rib. A curved fillet improves mold ability and rigidity more than one that is straight.