When there are holes, cavities or cores on the inside or outside of the injection-molded plastic parts that are different from the opening and closing directions of the mold, the plastic parts cannot be directly pushed out of the mold by a push mechanism such as a ejector pin. So we will make the movable parts that can move laterally, and then before the plastic parts are demolded and pushed out, the laterally formed parts can be pulled out first, and the plastic parts can be pushed out of the mold, otherwise it cannot be demolded. The entire mechanism that drives the laterally formed parts for lateral splitting and core-pulling and reset is called the lateral splitting and core-pulling mechanism. For the case of forming lateral bosses, it is often called side parting; for forming side holes or undercuts, it is often called side core pulling.
The main function is to get rid of the undercur on the plastic part, so that the plastic part can be smoothly released from the mold. The structures often used in the mold include slider core pulling, lifter core pulling, unscrewing core pulling, etc., and the slider can be subdivided into cavity slider, core slider, inner slider (tunnel slider) and so on.