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What exactly is molding? |
Molding is one of the most used methods of mass production of hollow parts like PET bottles, PVC pipes, tanks, cylinders etc etc. This process is comparatively very old and dates back to the early 18th century. Molding involves the shaping of pliable raw materials with the help of a rigid frame or model, which is called the pattern.
The Process of Molding
The molding process employs four generic stages :
- Heating
- Loading
- Cooling
- Unloading
Heating involves measuring the desired quantity of raw materials and subjecting them to high temperature so as to melt them. This process is followed by the Loading stage, where the molten material is poured into the molds or patterns to shape them. Once the molds are properly filled and the molten material is evenly distributed in the inside walls of the mold, the Cooling phase begins. The process of cooling is generally done by fan or in some cases by spraying water. This is the lengthiest process among all four. During this process the molten materials solidify and assumes the desired shape. After the molds are cooled enough, the Unloading phase begins, in which the moulds so formed are taken out by the operator.
Types of molding include:
- Compaction plus sintering
- Injection molding
Reaction injection molding
- Compression molding
- Transfer molding
- Extrusion molding
- Blow molding
- Rotational molding
- Thermoforming
Vacuum forming, a simplified version of thermoforming
- Laminating
- Expandable bead molding
- Foam molding
- Rotomolding
- Vacuum plug assist molding
- Pressure plug assist molding
- Matched mold
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