3D Printing v Injection Molding
Updated: Oct 14, 2020
There’s no shortage of stories these days of the old giving way to the new. From telecommunications to telemedicine, conventional ways of doing things are being pushed aside by newfangled alternatives.
But the transition is often a wrenching one, with the proponents of each side holding fast (see the battle between paper books and their electronic usurpers). Such is the strife-riddled scene that’s taking shape right now in the plastics manufacturing industry, as the fans of die-hard injection moulding put up their dukes against the guys with the fancy 3D printers.
Let’s have a look into the dustup.
No doubt, plastic injection moulding is a proven method of producing high-quality plastic parts with a long history of success. The arrival of the upstart 3D printing notwithstanding, more than 80% of plastic parts used in today’s products have to be injection moulded.
In the other corner, 3D printing is nothing short of a miracle—an innovative, affordable means of producing everything from houses to human prosthetics.
But each has its place.
3D printing is a good bet for small-quantity production. The undeniable magnificence of the technology aside, it takes a long time to 3D-print stuff. The cutoff point seems to hover around the 50-unit mark. Any runs smaller than that go to 3-D printing; injection moulding still reigns supreme for bigger runs.
The choice of materials available for 3D printing is wide and getting wider, but this process has simply not advanced to the point where the physical properties of its products are on par with their injection-moulded counterparts. In some cases, 3D printing is acceptable for prototype manufacturing only.
And the surface finish of plastic that’s been 3D printed still lags behind what a polished steel injection mould can produce.
Finally, the tolerances of a 3D-printed piece are still inferior to its injection-moulded alternative.
Finally, on matters of money, there’s no comparison. One study found it cost $20 apiece to 3D-print 300 units of a specific part; using a steel mould to produce the same number of the same piece cost just $1.13 per unit.