Plastic Injection Molding vs. 3D Printing

3D printing is a relatively new technology, and with its rise, manufacturers of plastic goods are excited to explore the possibilities of manufacturing using the 3D printing process. But what are the capabilities of 3D printing? Can 3D printing replace injection molding entirely as a way of producing plastic parts?

This is where you have to be careful. While 3D printing is a brilliant and promising technology that has very useful applications in the manufacturing process, it’s not quite able to replace the standard injection molding process just yet. Learning about the differences between plastic injections molding and 3D printing can help you to get the most out of each process.

What Is 3D printing?

3D printing is basically what it sounds like. During the manufacturing process, a special 3D printing machine is used to manufacture a plastic part through printing layers of the material onto the part until it’s complete. As with regular printing you’d do at home, the 3D printer is linked to a computer with a finished plan of what the part should look like once it’s done.

The benefit 3D printing has over injection molding – and the reason why many manufacturers are interested in whether or not 3D printing can replace plastic injection molding – is because (unlike plastic injection molds) 3D printing machines don’t have to be custom made for every part. What this means is that one machine can produce a relatively large amount of differently shaped parts.

With plastic injection molds, only one shape can be made by one mold, and that shape is determined by the mold cavity, of course. For different shapes, you need different molds, and having a plastic injection mold designed and made is rather costly.

This once again shows why manufacturers would be interested in a tool that can be used for any part without having to be specially made. It seems exciting, and like it can open up the world of manufacturing to brand new possibilities that would’ve been too costly in the past.

But how does injection molding really compare to 3D printing? Can manufacturers replace their injection molds with 3D printers now? Are 3D printers the future of manufacturing in the plastic industry?

Injection Molds vs 3D Printers

It’s true that 3D printing is a promising and exciting new development in the manufacturing industry. It’s also true that 3D printing can save manufacturers money when it comes to producing their final products. But currently the 3D printing process is just not sophisticated enough to replace plastic injection molding entirely.

The best use of 3D printing is for prototyping parts. You can save enormous amounts of money by having prototypes produces through 3D printing rather than injection molding while you’re still in the phase of designing a product that you aren’t mass-producing yet. This is especially the case if you only want one or two prototypes.

But apart from helping you save money on producing a small amount of parts for prototyping, 3D printing loses its appeal once you want to mass-produce a part.

The cost per part for 3D printing will be much lower than that of injection molding initially, but the more parts you produce, the smaller the price gap between 3D printing and injection molding will become. Eventually, the price per part will break even, and after that injection molding will once again be cheaper than 3D printing.

The number of parts you can produce before reaching the break-even point where injection molding and 3D printing costs the same per part will depend on the part you want to produce. But it can be surprisingly low sometimes, so you should look into the exact costs before assuming 3D printing will be cheaper.

Injection Molding Benefits

So, the relatively simple process of molding can still be cheaper than using clever computer software and a 3D printer. That comes as little surprise. But plastic injection molding is still superior to 3D printing in many other ways.

For instance, the molding process still has a much faster turnaround than that of printing. Which makes sense, since parts are produced through molding them in one go, rather than one layer at a time.

This is one reason why 3D printing still fails to be practical for mass-production. Compared to injection molding, it is painstakingly slow and you’d need a whole lot of printers to keep up with one single injection mold in terms of parts per hour.

But 3D printing is also less versatile. You’re restricted when it comes to what polymers you can use, so producing certain things through printing is literally still impossible in some cases. Meaning that you might not even be able to use 3D printing as a practical, cost-effective alternative for prototyping some parts.

And lastly, the versatility of injection molding allows you to create products of a higher quality.

So while 3D printing is exciting, it’s still far behind plastic injection molding. The technology will need to be improved to make it faster, more versatile and cost-effective for mass-production before it can realistically be used to manufacture high quality plastic parts. In the meantime, manufacturers should feel free to look into 3D printing for prototyping a small number of parts whenever possible.