Shades of grey

DEMM Engineering & Manufacturing - - 3D TECHNOLOGY -

A ‘less is more’ ap­proach has helped en­gi­neers in the UK make 3D printed parts lighter and stronger, us­ing meth­ods that will also make 3D print­ing faster and more eco­nom­i­cal.

The tech­nique uses a cut­ting edge process known as high speed sin­ter­ing (HSS). Un­like com­mer­cial 3D prin­ters that use lasers, HSS marks the shape of the part onto pow­dered plas­tic us­ing heat-sen­si­tive ink, which is then ac­ti­vated by an in­frared lamp to melt the pow­der layer by layer and so build up the 3D part.

Re­searchers from the Univer­sity of Sh­effield have dis­cov­ered they can con­trol the den­sity and strength of the fi­nal prod­uct by print­ing the ink at dif­fer­ent shades of grey and that the best re­sults are achieved by us­ing less ink than is stan­dard.

“All HSS work to date has in­volved print­ing 100 per cent black, but this doesn’t get the best re­sults,” says pro­fes­sor of man­u­fac­tur­ing en­gi­neer­ing Neil Hop­kin­son, from the Univer­sity of Sh­effield.

“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 re­searchers are able to ma­nip­u­late the den­sity of the ma­te­rial by up to 40 per cent, open­ing the door to the pos­si­bil­ity of 3D print­ing parts with dif­fer­ing den­si­ties at dif­fer­ent points.

This would en­able parts to have greatly re­duced weight but equiv­a­lent me­chan­i­cal strength – for ex­am­ple by hav­ing a dense outer shell and a lighter in­ner struc­ture.

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