Notes

Printrbot: Your First 3D Printer (Kickstarter).

Please let me know if I should include some other popular molding processes.

• Resin Infusion Molding



• Injection Molding



• Compression Molding



• Transfer Molding



• Reaction Injection Molding



• Extrusion molding



• Blow molding



• Rotational molding (Rotomolding)





• Vacuum forming (one of many thermoforming processes)



• Matched molding

Press the hot sheet between two matched molds. Using no vacuum or pressure, the parts can be easily formed producing crisp details and textured parts. The matched mold method and/or high pressure mechanical shaping of the hot sheets also enables thermoforming of thermoplastic composite materials.



• Trapped-Sheet Contact-Heat Pressure Forming



• Low Pressure Molding (LPM)

• Expended Polypropylene Molding (EPP)

The process uses pre-expanded EPP beads as a substrate. The preformed or non-formed TPO skin is inserted in the tool. The press closes and EPP beads are blown from behind the TPO trim. Steam fuses the beads to each other and also to the trim material. Water is sprayed on both sides of the tool until the part reaches an appropriate removal temperature. This process is developed by JSPI Corporation. One can use TPO bilaminate and steam PP beads behind it to reduce one fabrication step and cost. In mold skin-forming capability will make this process more attractive. The low tool cost investment is also very attractive for low volume applications.

EPP Manufacturing Process

Expandable Bead Molding Goes High-Tech

• Expanded Polystyrene Molding (EPS)

The mold used consists of two hemispherical parts that fit together forming an empty ball-shaped cavity. The two empty parts of the mold are filled with the pre-foamed eps beads. One part of the mold covered with a plastic plate is put on the other part. After the plastic plate is removed the two parts of the mold are bolt together. The eps-filled mold is placed for 10 minutes into a beaker containing boiling water. After fusing (molding) the mold is cooled down by cold water. Afterwards the mold is opened and carefully the polystyrene ball is taken from the mold.

• Back-Injection Molding

This process is performed by injecting a puddle of plastic in a nearly closed injection mold or by using a sequential valve gating system for melt injection. The process sequence follows: A TPO skin or skin/foam laminate is inserted, the mold clamps shut, the injected plastic flows and sets, and the finished part is cycled out.

• Back-Compression Molding

The TPO skin or skin/foam laminate is inserted in an open mold, the mold is partially closed and plastic is injected at controlled pressure behind the material followed by compression molding. Another variation of the process consists of 1) inserting the TPO cover stock, 2) deposition of melt strip in an open vertical mold by reciprocating screw extruder having X, Y, Z movement, 3) compression forming and cooling, and 4) demolding. This is known as Extrusion Deposition Compression Molding (EDCM).

• Vacuum plug assist molding



• Pressure plug assist forming



• Lost Foam Casting

involves:

1. Molding foam shapes that are direct replicas of your desired parts.
2. Coating the shape with a thin layer of ceramic coating.
3. Embedding the foam shape in dry unbound vibrated sand
4. Pouring metal into the mold dissipating and replacing the foam shape.



• Selective Laser Sintering

Sintering is a method for making objects from powder, by heating the material (below its melting point) until its particles adhere to each other



• Twin-Sheet Forming