Molding Practices

3D Printing vs Plastic Injection Molding

“3D printing” is a hot topic right now. There’s a lot of buzz surrounding this new technology, and rightfully so. It opens up many exciting possibilities for cost-effective plastic manufacturing in the future. But, what exactly is 3D printing? How does it work? Most importantly, what can we do with it, and how does it compare to our time-tested plastic injection molding capabilities? In this post, we’ll talk all about 3D printing, what it can do, and how it’s similar to and different from plastic injection molding.

1. What is 3D Printing, & How Does it Work?

As the name would suggest, “3D printing” involves extruding plastic resin into very precise shapes, creating three-dimensional parts with complex shapes one layer at a time. In basic terms, a computer-controlled machine squirts warm liquid plastic resin into flat layers, which stack up until the final part is formed. This is why 3D printing is known as an “additive manufacturing” process—all the flat layers “add up” to create almost any shape you could imagine. 3D printing uses inexpensive materials and doesn’t need a mold or any special tooling to make different parts. Plus, since the whole process is computerized, it’s easy to create almost any component with an incredibly high level of precision.

2. What Can 3D Printing Do?

Simply put, a lot! All you need is a correct computer model of the part you’re making, enough of the raw material, and of course, a 3D printer. This process is very efficient with material usage, wasting very little plastic and requiring minimal finishing work after printing. Also, since it’s a free-form process that doesn’t rely on molds, dyes, or other tooling, there are no limits to the shapes that can be made.

There are limitations to 3D printing, though. First, the parts you make can only be as large as the printing area in side of the machine. Also, the thickness of the layers your equipment can produce will create the final precision of the component and its outside surfaces. Finally, most current 3D printers on the market can only create one part at a time, meaning it may not be ideal for large-scale production. However, the technology is always improving, so many of these limitations may all but disappear in the future.

3. 3D Printing vs. Plastic Injection Molding

Here at Universal Plastic Mold, we specialize in plastic injection molding, which has its own set of advantages and disadvantages when compared with 3D printing. Instead of squirting liquid plastic into free-form layers, injection molding involves forcing liquid plastic into a metal mold, which has been precisely machined into the final outside shape of the plastic part. This process is great for high-volume production, offering cost-effective speed compared with the current 3D printing technology. But, when it comes to prototyping or small-volume production, it can be costly to redesign, machine, and swap out the custom molds and tooling needed for injection molding. 3D printing allows you to make small changes in the design of the part without costly retooling, so it’s perfect for developing new parts.

Also, because injection molding requires a negative mold, there are real limitations to the shapes and geometries of the parts it can produce. Obviously, once you’ve molded a part, you have to be able to remove it from the mold, so certain shapes just won’t work. Injection molding can also be slightly less efficient with material usage, as parts must be made with extra bits (such as “ejector pins”) that will need to be removed in the finishing process, leading to some wasted plastic. Finishing can also be a bit more involved with injection molding, as most parts will end up with a visible seam where the two halves of the mold come together, as well as extra tooling marks and those ejector pins we mentioned earlier.

The bottom line is that plastic injection molding and 3D printing compliment each other, each with their own advantages and drawbacks depending on the application. 3D printing might be the hot manufacturing technology of the future, but injection molding is in no danger of becoming outdated any time soon. When used together, they offer fast, cost-effective ways to make plastic parts from prototyping and short-run production all the way up to full, large-scale manufacturing with the lowest unit costs possible.

Want to find out which plastic manufacturing method is best for your parts and your needs? Just call us at 1-888-893-1587 or contact us today to speak with our team. We’ll be happy to consult with you and help you find the best way to handle your production requirements.

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