5 Steps to Producing an Injection Molded Plastic Part

dnp pack -summer colorsDuring a moment of brilliance or even years of research you have invented the perfect plastic part, but now how do I get it manufactured for all mankind to use? We get lots of phone calls asking that very question, and most have no idea of the process used to get from a concept to a finished molded part.  Here’s the short answer to that question!

Plastic Part Design

1.  Provide us your idea in as much detail as you can.  We work from napkin sketches all the way up to full CAD drawings, but we do have to establish the basic dimensions of the part.

2.  We will then “computer build” that part using the latest CAD drawing tools.  This creates a complete 3-D model of the part in the computer that defines every point on that part.  We usually send shaded renderings to you for your approval via .pdf files.

Prototyped with 3-D Printing Upon Approval

3.  Once approved, we usually then send the CAD file to a full service 3-D printing facility where they download the file into the printer and it drives a laser through a vat of liquid or powdered plastic, building the part layer by layer.  The finished part is then an exact replica of the molded part that can be used for show and tell or actual functional testing.  It still won’t be a perfect copy of the molded part in all performance characteristics because the materials are different, but it does prove out the design in many ways.

Injection Mold Building

4. Once refinements and/or corrections are made based on the prototype part, we then use the same CAD file to design and build the actual steel mold for production use.  The material has to be pretty well established first because different plastics shrink at different rates as they cool, and the mold has to be machined slightly larger than the part to compensate for the shrinkage.

5. Once the mold is done, parts can be sampled very quickly for approval, with production starting immediately after that.

This entire process can take anywhere from a month to six months depending on the complexity of the part.  Cost also increases with complexity.  Prototypes can range from a few hundred dollars to a few thousand, and the molds usually start around $10,000 and can easily exceed $100,000 for very complex parts or molds with lots of cavities (parts produced on each cycle) to handle high production volumes.  Injection molding is still the most common process for producing a plastic part!


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