As a plastic injection molder, it surprised many when we entered the additive manufacturing industry with the creation of rp+m in 2012. Why would we entertain the thought of starting a company whose industry was considered a direct threat to plastic injection molding? Simple, we believed that this technology would pair well with injection molding.
While the two technologies may be complimentary, there are still times when one will be a better choice.
Plastic injection molding is the most popular method to make plastic parts. One reason is cost. If you need thousands of parts produced annually, plastic injection molding would be the most cost effective, even when factoring in the tooling. While a tool will cost thousands of dollars, the actual piece price for the part may run as low as a few cents (if a very small part made of a common polymer). Even small parts produced via additive manufacturing will cost tens of dollars per part – price for thousands of parts and you will quickly match the cost of plastic injection molding.
If you need a small plastic part made but only need a few of them – additive manufacturing is your better choice. When only a few parts are needed the cost for tooling in plastic injection molding is prohibitive. Additive manufacturing is the better choice for lower part quantities.
Sometimes you have a part design that isn’t quite there but you need to know where exactly the issues might be with the part. Additive manufacturing is your best choice. Your CAD design can be uploaded and the part made in hours. You can then have your part in-hand to review and decide what changes need to be made to the design.
The time it takes to make your parts truly depends on the size and number of parts you need. If you need just a handful of parts, additive manufacturing is absolutely the most efficient choice to produce the parts. If thousands of parts are needed throughout the year, then plastic injection molding is your best choice when mass-producing.
While there have been great strides in additive manufacturing to create high quality parts, injection molding can produce a part that typically has a better appearance to it and can be made with various surface finishes (including in-mold labeling and diamond-finishes).
Complexity in design with 3D printing
Overmolding and high gloss finish with injection molding
Even four years later we firmly believe that plastic injection molding and additive manufacturing are complementary technologies that can exist on their own or work together. If you have a part design but want to have the opportunity for design iterations before committing, you could have the part made via 3D printing and oncethe design is confirmed, then move forward to mass-production via injection molding. We are very excited to see what the next stages will be with additive manufacturing and how it will continue to work with plastic injection molding.