Study on the Online Monitoring of Burn Marks by Gas Sensor

Abstract

Burn marks are serious defects in injection-molded parts that can result in many defective products. There is thus a great demand for effective systems to reduce these defects in injection-molded products. In this study, we investigate the relationship between gas generation and molding conditions using gas sensors. The results show that gas sensors can be used to monitor burn marks.

Reducing the Burn Marks on Injection-Molded Parts by External Gas-Assisted Injection Molding

“…The influence of mold structure and molding parameters on the burn marks has been studied [ 9 , 10 , 11 ]. Yao et al [ 9 ] proposed an automated design methodology to minimize the burn marks by optimizing the mold design, and the burn marks were eliminated with the optimized gate location.…”

“…However, it is not always possible to modify the gate location or mold structure of injection molds. Fukushima et al [ 11 ] investigated the influence of molding parameters on the burn marks and found that the burn marks decreased with a decrease in injection speed within a certain range. It provides guidance for reducing the burn marks, but it does not always work in the molding of all parts.…”

“…The burn marks are caused by high local temperatures of a polymer, usually due to the high pressure of trapped air in the mold cavity [ 11 , 12 ]. External gas-assisted injection molding (EGAIM) has been reported to reduce the holding pressure in the mold cavity [ 13 , 14 , 15 ], which will perhaps reduce the pressure at the air-trapped positions and hence reduce the burn marks.…”