What is compression molding?
Compression Molding is a plastic processing process used to manufacture plastic parts with complex geometries, often involving hard materials such as thermoset plastics and composites. The main feature of this process is that heated plastic material is placed in an open mold and then pressure is applied to allow it to fill the mold and solidify into the desired shape. Compression molding is generally suitable for low-volume production and the manufacture of parts that require high precision.
The following is the basic working principle of compression molding:
1. Prepare the mold: First, you need to prepare a pair of molds, usually made of metal, to make parts of the desired shape. These molds include a fixed upper mold and a movable lower mold. The internal shape of the mold matches the shape of the desired part.
2. Melt plastic: Heat the desired plastic pellets or pellets to a molten state. Typically, this is done by placing the plastic in a mold and heating the entire mold.
3. Loading: Once the plastic reaches a sufficient molten state, the molten plastic material is placed in the lower mold.
4. Close the mold: The lower mold moves and closes, extruding the plastic into the shape of the upper mold. This can also cause too much-molten plastic to be squeezed out of the mold.
5. Apply pressure: By applying pressure, usually hydraulic pressure, the upper and lower molds are held closed, ensuring that the plastic fills the mold and fits tightly against the mold walls.
6. Cooling and solidification: Under the conditions of heating and pressure, the plastic material will cool and solidify into the desired shape. This usually takes a while to ensure the plastic is fully cured.
7. Open the mold: Once the plastic solidifies, the upper and lower molds separate, allowing the finished part to be removed.
Compression molding is generally suitable for manufacturing high-quality parts such as electronic casings, electrical insulation components, engineering plastic parts, composite products, etc. Compression molding has several advantages over other plastics processing processes, including the ability to manufacture complex geometries, no need for special injection or extrusion equipment, suitability for a wide range of hard materials, and availability for low-volume production. However, it is usually not suitable for mass production due to long production cycles and high labor costs.