How to Mass Produce Plastic Parts: Machining vs. Molding

how to mass produce plastic partsWhen deciding how to mass produce plastic parts, several factors have to be taken into consideration. Depending on the application, the method with the lowest part cost can sometimes end up being more costly in the long run. If your parts need tight tolerances and superior surface finishes, CNC machining is the way to go.

How to Mass Produce Plastic Parts for Demanding Applications

Companies often turn to injection molding because it yields repeatable parts with the lowest part cost over large runs. However, producing the initial mold is expensive and time consuming: depending on the complexity of the mold, it could cost anywhere from $5,000 to $200,000. And once created the mold cannot be changed, which means any alterations to your part design would require a new mold. Additionally, injection molded parts are prone to cosmetic defects, such as ejector marks, warping, and bubbles.

That is why CNC machining is often a better choice for mass producing high performance plastic parts. With CNC machining you get:

Greater precision and tighter tolerances – With injection molding you can expect results within .005” of specifications, whereas CNC machining can provide tolerances within .001”.

Better surface finishes – CNC machining can produce surface finishes as smooth as 15Ra and free from cosmetic defects. In fact, secondary machining is often used to correct defects found in injection molded and 3D printed parts.

Faster turnaround time – It takes approximately 8-10 weeks to produce the tooling for an injection mold. CNC machines, on the other hand, start producing parts as soon as the design has been programmed into them. This can greatly reduce production times, especially if your project is running behind schedule.

More complex designs – CNC machining allows for the production of intricate, complex, uniform parts. Designs that would require multiple injection molded parts can often be coalesced into a single machined part, cutting down on fabrication and part costs.

Design flexibility – If the design of your plastic part is likely to change, it is financially inefficient to invest in an expensive mold that will be rendered unusable with a single design alteration. CNC machines are the best choice for changing designs because they can be quickly reprogrammed to produce the latest version of your part, minimizing downtime and outdated parts.

Advanced materials – While flexible materials are ideal for injection molding, many harder, high-performance specialty plastics can only be machined. It is important to be able to use the best material to meet specific standards or applications. For demanding, high-performance applications, it’s possible machining is your only option.

Reading Plastic: a Trusted Source for Mass Machined Plastic Parts

For nearly four decades, we at Reading Plastic have been known for our industry knowledge, ability to hold close tolerances, and excellent customer service. We have worked with clients in every industry to produce projects of any size. If you’re ready to discuss your project, call us today at (610)-926-3245 or email

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