The plastic crate mold is a plastic processing mold, which is prepared from plastic mold steel such as 45 steel, P20, and 718. Analysis of the failure of plastic molds can better guide the development of mold steel. The failure modes of plastic molds are:
1. Wear and corrosion of the mold cavity surface of the crate
1) The plastic melt flows in the cavity with a certain pressure, and the solidified plastic parts are released from crate mold, causing friction on the molding surface of the crate mold and causing wear.
2) Reinforced resin filler in plastic will cause erosion, wear and corrosion on the surface of the mold cavity of the tote.
3) At the same time, chlorine, fluorine and other components in the plastic processing are thermally decomposed to corrode gases HCl and HF.
These cross-overs can cause damage to the coating or protective layer on the surface of the cavity, causing wear and corrosion.
2. Failure of plastic deformation of the crate
1) The surface of the plastic model cavity is pressed and heated to cause plastic deformation failure, especially when the small tonnage box mold works on large tonnage equipment, it is more likely to cause overload plastic deformation.
2) The material used in the plastic crate mold has insufficient material strength and toughness, and the deformation resistance is low.
3) The hardened layer on the surface of the mold cavity of the plastic crate is too thin, the deformation resistance is insufficient or the working temperature is higher than the tempering temperature to cause phase change softening.
These can cause damage to the surface of the crate mold, such as depressions, wrinkles, pitting, corner collapse, and the like.
3. Breakage of plastic crate mold
1) The shape of the plastic crate mold is complicated by many corners, thin walls, etc., and local stress concentration at these parts will cause fracture.
2) Structural stress, thermal stress caused by temperature difference or insufficient tempering, the retained austenite transforms into martensite at the use temperature, causing local volume expansion, resulting in tissue stress inside the crate mold.