No abstract

Fresnel lenses are becoming more and more important because they are widely used as optical elements for concentrating solar power. Micro-hot embossing is a promising approach to fabricate Fresnel lenses. Precision optical elements must be more quickly and cheaply introduced to the market due to the pressure of global competition. The thermal conductivity of Aluminum (Al)-filled epoxy resins is lower than that of conventional mold steel materials. This work demonstrates a technique for fabricating hybrid rapid tooling with different backing materials to investigate the demolding efficiency in the hot embossing process. It was found that the Al was strongly recommended as backing material for fabricating hybrid rapid tooling due to cost, demolding time efficiency and dimensional accuracy of the embossed parts. Demolding efficiencies for the hot embossing mold with backing materials of copper, aluminum and steel about 78 %, 68 % and 50 % can be enhanced compared to that of the conventional rapid tooling. The replication rate exceeding 96 % in the hot embossing mold manufacturing process can be reached. The transcription rate exceeding 93 % in the hot embossing process can be obtained.

Micro-injection molding or micro-hot embossing is a highly effective process for fabricating micro-devices with microfeatures in polymer. Based on the strong demand on the precision components in the precision machinery industrial, two major concerns are the time and expense required for producing a precision mold for microfabrication. To enhance the competitiveness in the market of micorcomponents, this study presents six approaches for manufacturing precision epoxy resin molds with microfeatures. Evolutions manufacturing processes are described experimentally. Characteristics and applications of micro-featured epoxy resin mold are introduced in detail.

Micro-hot embossing is a highly effective process for fabricating micro-devices with microfeatures in polymeric materials. One of the most troublesome problems in precision machinery industry is the time and expense needed to produce a mold for microreplication. Epoxy resin mold has been successfully employed for microreplication using micro-hot embossing. However, the junction of the groove and sprue of the backing plate has serious local stress concentration, leading to the reduction of lifespan of a precision epoxy resin mold during the micro-hot embossing molding. This work presents an effective method for enhancing the lifespan of a precision epoxy resin mold using reduction of local stress concentration. The numerical models were developed for predicting the maximum stress using ANSYS software. The ANSYS simulations have been carried out and the predicted results show good agreement with experimental tests. The junction of the groove and sprue of the backing plate was machined with chamfer to revaluate lifespan of the epoxy resin mold using micro-hot embossing molding. Micro-hot embossing verification test showed that the lifespan of epoxy resin mold with chamfer is about 2.2 times that of the conventional epoxy resin mold.