Are 3D-Printed Polyurethanes Durable?
Dispelling some common myths about additive manufacturing and PU
By Dr. Bart Engendahl, Managing Director - Germany
Unfortunately, 3D printing has earned a reputation as a crutch for printing throw-away novelties or prototypes, rather than a real tool for manufacturing durable parts for use in machinery and other heavy-duty applications. With recent advances in technology, that's far from the truth. Additive manufacturing can be used to produce commercial volumes of functional, durable end-use products — even when flexible materials are required.
Myth #1:
Additive manufacturing doesn't offer the same materials you're accustomed to working with.
These days, it's possible to print the same material you're used to getting from traditional manufacturing, such as injection molding. Instead of creating a new material to approximate an existing one, Chromatic uses custom chemistry to work in reverse: taking the material you need and making it printable. Whether it's a Shore A 90 buffer for a vintage bogie or a rugged yet very flexible membrane for a modern air brake, the requisite material properties for your industrial spare parts are now feasible via additive manufacturing.
Myth #2:
3D-printing materials aren't viable in Shore hardness 40–90.
Shore A 40 to 90 is an especially difficult hardness range in which to print high quality parts. For example, fused filament fabrication materials, including thermoplastic polyurethanes, are limited to Shore A 70 and above. Meanwhile, 3D-printed acrylate-rubber photopolymers are available on the softer end of the Shore A hardness scale, but they're not durable.
Although additive manufacturing materials have indeed been limited in the past, technology has improved. Chromatic 3D Materials' thermoset polyurethanes range from Shore A 50 to 90 in hardness.
Myth #3:
Flexible 3D-printing materials are weak.
Until now, one of the primary problems with additive manufacturing has been strength, particularly when it comes to flexible materials. Chromatic's production-grade materials have high tensile strength — up to 18 megapascals — and elongation at break can be as high as 550 percent.
Take a recent project Chromatic did for Lee J. Sackett, Inc. for example. We 3D printed a set of functional track pads for tractor, which are durable enough to drive around on!
Myth #4:
3D-printed polyurethanes aren't viable for industrial environments.
In addition to basic material properties such as hardness and tensile strength, industrial parts must withstand a range of other environmental factors. Extreme temperatures, high pressure, oils, and fats are all part of the package in industrial environments.
Chromatic's materials are suitable in temperatures up to 150 degrees Celsius and as low as -40 degrees Celsius. Hundreds of bars pressure and oils, such as those for hydraulic or heat-transfer applications, are no problem either.
Myth #5:
3D-printed components aren't durable in the long run.
Of course, it's not just the virgin properties of a material that matter — the material has to endure. Chromatic's materials exhibit long-term stability. These cross-linked materials can be bent and stretched, over and over and over again, without warping or cracking.
After a heat-aging treatment of 72 hours at 100˚ Celsius, our ChromaLast 65 showed Shore A hardness of 64 (compared to 60 after post-cure at 100˚ Celsius for 18 hours). Elongation at break was 664% compared to 618% initially, and peak stress was 19.9 megapascals compared to 18.4.
And whereas most 3D-printed parts have seams or voids, Chromatic's additive manufacturing technology yields full-density parts that are free of such points, which can lead to premature failure of a part. Chromatic's parts are printed to last.
Further reading
If you’re interested in learning more about 3D printing with durable materials, read our blog post about additive manufacturing with elastomers.