Standard Molding

Standard Molding


Material Preparation

Plastic pellets are loaded into a hopper. These pellets serve as the raw material for the process.


Melting the Plastic

The plastic pellets from the hopper are transferred to a heated barrel, where they are melted. This is achieved using a combination of the barrel’s heaters and the frictional heat generated by a reciprocating screw inside the barrel.  The screw mixes and melts the plastic as it pushes the molten plastic forward.


Injecting the Plastic

Once the plastic is fully melted and the mold is prepped, the screw (acting as a plunger) pushes the molten plastic forward, injecting it into a closed mold under high pressure.


Cooling and Solidifying

After injection, the molten plastic begins to cool and solidify, taking the shape of the cavity inside the mold.  The mold’s cooling system (usually circulating water) helps expedite this cooling process.



Once the part has fully cooled and solidified, the mold is opened.  An ejection system, which can include pins, a plate, or other mechanisms, pushes the part out of the mold.


Part Inspection and Trimming

After ejection, the part is inspected for quality.  Any excess plastic, such as runners or flash, is trimmed off. Depending on the mold design and the material used, some of these excess parts (like runners) can be reground and reused.



The process is cyclical. Once a part is ejected, the mold closes again, and the process starts from step 2 with the melting of more plastic.


Key Components of the Standard Injection Molding Machine:

a)    Hopper: Where the plastic pellets are loaded.
b)    Barrel: The chamber where the plastic is melted.
c)    Screw: Mixes and pushes the molten plastic into the mold.
d)    Clamping Unit: Provides the force to close the mold and resist the pressure exerted by the molten plastic during injection.
e)    Mold: A precision-manufactured tool that defines the shape of the final product. It consists of two halves (core and cavity) that come together during the injection process.
f)    Ejector Pins: Help in pushing the cooled part out of the mold.



The success of the standard injection molding process is influenced by various parameters, including the type of plastic material used, melt temperature, injection speed and pressure, mold temperature, and cooling time. Adjustments to these parameters can help optimize the process for specific materials and desired part characteristics.

Overall, standard injection molding is a versatile and efficient method for producing a wide range of plastic parts, from simple to complex geometries, in large volumes.

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