Gates are the purpose the place the melted plastic enters the cavity. Women’s House Shoes The position and geometry of a gate control the circulate into the part. A part is created by two or more tools transferring together to create a closed quantity, into which plastic is injected under pressure. If you find thin layers on the surface of a molded part are simply separating or peeling off the underlying material, you’re seeing a molding defect known as delamination. Delamination is a defect characterised by a flaking surface layer, just like what you’d generally discover on flake mica.