Introduction to injection molding

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Injection molding is a common manufacturing process

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used to produce high volume plastic parts.

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Everyday items such as food storage containers, cell phone cases,

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automotive parts and housings are all manufactured using injection molding.

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In this video,

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we will illustrate the basic components of an injection molding machine

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describe the phases of the injection

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molding simulation cycle including the filling phase

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which is impacted by part design

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packing and cooling phase which impacts the quality of the mold part

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and the ejection phase which influences how much the part warps.

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The injection pulling process starts with an injection molding machine.

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The injection molding machine contains three distinct sections.

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The injection unit,

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the clamping unit

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in the mold that makes the various plastic parts,

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plastic pellets are fed into the hopper attached to the injection unit

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from the hopper.

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They move into the barrel where they are melted by the reciprocating screw.

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An important fact about plastics is they expand slightly in

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volume as they transition from the solid to the liquid state

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and shrink as they cool back down and solidify.

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This has significant implications in the injection molding process

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and must be compensated for during the molding cycle.

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The reciprocating screw moves forward and injects the

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slightly higher volume molten plastic into the mold

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as the plastic fills the mold. However, it is already starting to cool.

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This is the filling phase and takes from as

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little as 0.1 seconds for small parts like electrical connectors

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to 5 to 10 seconds for larger parts such as automotive bumpers or waste containers.

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Once the mold cavity is filled,

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the shrinking cooling plastic can leave empty caps in the mold

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to compensate for the volumetric shrinkage that occurs as the plastic solidifies,

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extra material is forced into the mold under high pressure.

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When no additional material can be forced into the mold,

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the pressure is released and the part

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continues to cool to the ejection temperature.

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This is the packing and cooling phase.

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When the part reaches the ejection temperature,

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the mold opens and the part is ejected,

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the mold closes and the process is repeated.

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This is called the ejection phase

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injection molding simulation infusion 360 simulates

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this process enabling you to discover if

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your design can be injection molded to produce a high quality part.

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In this video, we reviewed typical injection molded parts,

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looked at the basic components of an injection molding machine

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and talked about the various steps within the injection molding process,

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including the filling phase,

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the packing and cooling phase

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and the ejection phase.