Development of an Epoxy-Based Rapid Tool with Low Vulcanization Energy Consumption Channels for Liquid Silicone Rubber Injection Molding

Abstract

Liquid silicone rubber (LSR) parts have some distinct characteristics such as superior heat stability, low-temperature flexibility, aging resistance, and chemical resistance. From an industrial standpoint, the uniform vulcanization temperature of LSR is an important research point. However, the uniformity of the vulcanization temperature of LSR has been limited since the layout of the cartridge heater incorporated in the conventional steel mold does not follow the profile of the mold cavity. Metal additive manufacturing can be used to make LSR injection molds with conformal heating channels and conformal cooling channels simultaneously. However, this method is not suitable for a mold required to develop a new LSR product. In this study, a cost-effective approach was proposed to manufacture an LSR injection mold for the pilot run of a new optical lens. A rapid tool with low vulcanization energy consumption channels was proposed, which was incorporated with both a conformal heating channel (CHC) and conformal cooling channel (CCC) simultaneously. The function of the CHC was to vulcanize the LSR in the cavity uniformly, resulting in a shorter cycle time. The function of the CCC was to keep the LSR in a liquid state for reducing runner waste. It was found that the equation of y = −0.006x3 + 1.2114x2 − 83.221x + 1998.2 with the correlation coefficient of 0.9883 seemed to be an optimum trend equation for predicting the solidification time of a convex lens (y) using the vulcanizing hot water temperature (x). Additionally, the equation of y = −0.002x3 + 0.1329x2 − 1.0857x + 25.4 with the correlation coefficient of 0.9997 seemed to be an optimum prediction equation for the solidification time of a convex lens (y) using the LSR weight (x) since it had the highest correlation coefficient. The solidification time of a convex lens could be reduced by about 28% when a vulcanizing hot water temperature of 70 °C was used in the LSR injection mold with CHC.

Potential of New Sustainable Green Geopolymer Metal Composite (GGMC) Material as Mould Insert for Rapid Tooling (RT) in Injection Moulding Process

“…Geopolymer can be used to replace epoxy since it is robust and strong and is now utilised in building concrete. In addition, it preserves the environment, reduces cost, and supports sustainability of waste management systems [ 81 , 94 , 95 , 104 , 105 ]. As an implication, industries related to mould-making will benefit the most due to the reduced cost when using recycled materials.…”

Study on the effect of the molding process on the uniformity of rubber products

“…16 In a related vein, Kuo et al innovated an LSR injection mold to advance LSR vulcanization uniformity. 17 However, existing research predominantly gravitates toward elucidating the impact of varied process parameter adjustments on rubber flow homogeneity during the molding process, typically within the confines of the same molding methodology. A notable gap in the literature pertains to the absence of comprehensive investigations concerning the post-molding homogeneity of specialized rubber products.…”

“…The study by Nakanishi et al centered on refining the blending process for EPDM rubber, elevating both homogeneity and performance 16 . In a related vein, Kuo et al innovated an LSR injection mold to advance LSR vulcanization uniformity 17 . However, existing research predominantly gravitates toward elucidating the impact of varied process parameter adjustments on rubber flow homogeneity during the molding process, typically within the confines of the same molding methodology.…”