Injection moulding offers high speed, efficient manufacturing, while 3D printing is great for rapid prototyping, customisation and complex structures. What if the two could be combined?
A researcher at the University of Massachusetts Lowell has achieved just that with a new technique known as injection printing, aimed at addressing speed, strength and accuracy issues within the growing $4bn plastic 3D printing market.
Plastics engineering professor David Kazmer tackled those issues by combining material extrusion of outer surfaces of parts at fine resolution, with injection moulding of larger interior cavities at high flow rates. The denser parts have more isotropic properties that approach injection moulding.
The combination reportedly increases the production rate of 3D printing while enhancing the strength and properties of the resulting products. The technique typically produces objects about three-times faster than conventional 3D printing, according to Professor Kazmer. Increased strength could lead to more durable prosthetics and medical devices, or stronger parts for aircraft and cars.
“The invention greatly improves the quality of the parts produced, making them fully dense with few cracks or voids, so they are much stronger,” said Professor Kazmer. “For technical applications, this is game-changing. The new process is also cost-effective because it can be used in existing 3D printers, with only new software to program the machine needed.”
Compared to material extrusion, the stiffness, strength and strain to failure of ‘in plane’ injection printed tensile bars increased by 21%, 47% and 35% respectively.
The research was published in Additive Manufacturing.
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