New 3-D printing technique controls product density, strength

Researchers from the University of Sheffield are using a technique that has allowed the creation of lighter, stronger 3-D printed parts, and is faster and less expensive than commercial 3-D printing.

The process of high speed sintering (HSS) marks the shape of the part onto powdered plastic with heat-sensitive ink. The ink is activated by an infrared lamp which melts the powder layer by layer to build the 3-D part. They found that by printing the ink in different shades of gray, they can manipulate the density of the final project by up as much as 40% and control its strength.

“All HSS work to date has involved printing [with] 100% black [ink], but this doesn’t get the best results,” Neil Hopkinson, PhD, professor of manufacturing engineering for University of Sheffield, stated in a press release. “We found that there is a point at which, as the ink levels increase, the mechanical properties start to reduce. This enabled us to identify the ‘sweet spot’ at which you can gain maximum strength with the minimum amount of ink.”

The technique will allow the creation of 3-D printed parts with different densities at different points, such as a product with a dense outer shell and light inner structure. Hopkinson said the emphasis on a process that optimizes the material of the product rather than the shape of the part will creates opportunities for commercial manufacture and improve recycling possibilities. It also will reduce the cost of 3-D printing by reducing the volume of ink energy needed to create products. Hopkinson said he envisions use of the technique in the sports footwear field, as it would allow dual density foams to be printed using one material.

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