What is Injection Molding?

Update Time:2018/5/22
What is Injection Molding?

Injection molding is by far the primary process for converting plastics into useful plastic widgets. Just about all of us touch an injection molded widget every hour of every day. All thermoplastics can be injection molded with a few exceptions like polyimides and PTFE to name a few. Injection molding takes pelletized materials and heats them up to the point where they can flow properly through the injection process. The hot, molten material is then injected into a closed mold to create the desired part or shape. Then, after the part cools, the part is removed from the mold.

Advantages of injection molding:

-Extremely high output rates.

– Inserts and fillers can be used with this process.

– Process can be completely automated and run with little downtime.

– Scrap from the process can be ground and reused into the process.

– Small, complex parts can be molded economically.


-No cost effective for short runs.

-Large capital investment in equipment and overhead required.

-Molds can be very expensive requiring large runs to justify ROI of tooling.

-Requires a high degree of design and process expertise and experience to produce good parts and have low scrap rates.

-Thick cross sections can not be easily or reliable produced.

Injection molding will always be the number one way that large volume plastic parts are produced. When a part volume is too small or need to be tested before a final investment is made in tooling, machiend plastic stock shapes are the go to method for producing reliable plastic parts.

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