Undercuts at all times add cost, complexity, and maintenance necessities to the mold. For functions with less strict necessities other supplies, like ABS, polypropylene and Polyethylene , are extra common. Hot ideas are sweater dress immediately related to the spur and inject plastic from the highest facet of the part. No material is wasted this way on the runner system making them ideal for large scale manufacturing, but a dimple will be seen at the injection level. Post gates inject the material from the bottom of the cavity, hiding the small imperfection left from breaking the opposite gate varieties. These gates are used for elements that require glorious visible look.