Forming process where a part is made of two or more subsequent injections building on the previous injection. Beskrivning The process Plastic pellets [1] are supplied via a hopper into a rotating screw [2] whose spiral shape moves the pellet forward through a heated chamber [3].The pellets are heated gradually and turns into a homogeneous plastic melt as it approaches the end of the helical screw. The molten mass is pressed in a mold [4] as the entire screw is pushed forward by an applied pressing force. The injection molding occurs in two steps with a rotating mold. First part of the rotating mold is filled with molten polymer [A], after which it is withdrawn, rotated 180 degrees and re-clamped before an additional injection is made [B]. In this way one can create parts that have different colors or different kinds of materials in which no adhesive is required between the layers. If the part's design allows it to have more shots of injection molding it can be carried out with the so-called pull-back technique. After the first batch is pressed one mold half is pulled back slightly to then fill the void that occurs with a second batch of material. Injection molding Plastic forming process where the plastic pellets are fed in and melted in a container with a rotating screw and pressed into a mold. Read more Injection over molding Advantages and disadvantages In comparison with alternative methods Reduced cycle time improved adhesion, reduced unit costs Can cast parts made of different polymers Expensive capital investment Complex tools Only limited forms can be produced
