Epoxy resin casting technology is a novel manufacturing technology for insulating materials that emerged in the 1950s, arising alongside the development of power transmission and transformation technology. Early power transmission and transformation equipment had low voltage levels, and its core insulating components still used traditional insulating materials. As the voltage levels of power transmission and transformation equipment increased, the shortcomings of traditional insulating materials became apparent, particularly their inability to meet the requirements of power frequency withstand voltage and partial discharge. To solve these problems, epoxy resin casting technology was developed.
In the 1950s, the epoxy resin casting process was similar to metal casting, involving heating epoxy resin and pouring it into a metal mold, either at room temperature or with heating. Because the epoxy resin material system, casting formulation design, casting equipment, and casting process were all in their early stages, the internal and external quality of the cast products was relatively poor.
In the 1960s, vacuum casting technology appeared, transforming epoxy resin casting from atmospheric pressure molding to vacuum forming. Vacuum casting allows for easier removal of air bubbles from the casting material, significantly improving both the internal and external quality of the finished product. This propelled the development of power transmission and transformation technology. However, during this period, users primarily focused on internal performance, paying less attention to appearance quality.
In the late 1970s, my country began introducing complete microcomputer-controlled vacuum systems. Vacuum technology was implemented across the entire process, from material pretreatment and piping systems to mixing and casting systems, with increased automation, elevating the quality of cast products to a new level.
Today, material systems and formulations are highly mature, casting equipment is intelligent, and product performance fully meets the requirements of high-voltage power transmission and transformation equipment. Currently, epoxy castings for the highest voltage level megavolt power transmission and transformation equipment are domestically produced. At this point, appearance quality has become the focus of user acceptance and manufacturer attention, and is fundamental to the market competitiveness of epoxy casting products.
Because the appearance quality of epoxy casting products is affected by numerous factors, accurately quantifying and determining the causes of problems is difficult. Therefore, controlling the appearance quality of castings has become a challenging aspect of casting process technology. Currently, the level of appearance control for cast parts abroad is far higher than that of similar products in China.
