The standard polyurethane casting process typically includes the following steps: Raw material pretreatment, metering and mixing, casting, curing, and post-treatment.
First, raw material pretreatment: Polyols require heating and dehydration, while isocyanates need to be kept sealed and moisture-proof. The temperature is usually controlled between 40℃ and 80℃ to ensure fluidity and reactivity.
Second, metering and mixing: Precise proportions are crucial; the error should generally be controlled within ±1%. Mixing methods can include mechanical stirring or high-pressure impact mixing, with the latter resulting in more uniform mixing.
During the casting stage, the mixture needs to be rapidly injected into a preheated mold. The mold temperature is typically controlled between 50℃ and 100℃ to ensure sufficient reaction and reduce internal stress.
The curing process consists of two stages: Initial curing and post-curing. Initial curing is usually completed in the mold, while post-curing takes place in an oven to further improve material properties.
