They call it high speed sintering, or HSS, and it might represent the watershed moment when 3D printing (or additive manufacturing) takes over from injection molding processes in creating production runs of plastic and metal parts for industry and consumer goods.
Advanced polymer sintering at very high speeds has been the focus of work at the University of Sheffield and its commercial incarnation, FaraPack Polymers, for quite some time now. The team is at the forefront of investigating laser sintering for low-volume applications and HSS for high volume part production.
Working with industry partners and in conjunction with Loughborough University – the owners of patents relating to HSS processes – the aim is to demonstrate the time-saving and cost benefits of using AM for high-volume output.
Called the FACTUM project, the group has been awarded nearly $2.5 million in funding from the UK's Technology Strategy Board and various industry sources to examine and refine the technology.
The brainchild of Professor Neil Hopkinson, now at the University of Sheffield in the Department of Mechanical Engineering, HSS was invented during Hopkinson's tenure there, but the rights to the intellectual property underlying HSS stayed with Loughborough.
"We believe this is the first time such a company has engaged in a publically-funded project in which they have invested substantial resources of their own, with a target of using additive manufacturing for end-use products," Hopkinson said. "Fast-moving consumer goods are produced in high volume, and thus far, that's not worked with additive manufacturing economically. The viability of additive manufacturing at high volume is one of the key unique features for this project."
Now a mature, five-year-old process, HSS uses a hybrid of new and old processes to output objects in a fraction of the time of previous methods. The device uses inkjet print heads to lay down a binding agent in a bed of powdered material, but rather than utilizing a laser to sinter the materials, it uses infrared heating lamps capable of melding a larger area more quickly than standard lasers.
And it's fast. The developers say FACTUM can produce parts about the size of a human finger in something like 10 seconds.
As an added bonus, according to UK additive manufacturing giant Renishaw, who have extensively tested the FACTUM, parts created with the process are actually more precise than parts built using laser sintering.
FACTUM may well have advantages beyond speed and precision. The researchers say many popular materials which are unsuited for the laser sintering process work well when used in HSS. It comes down to the workings of the process and how materials are heated. While the infrared heating lamps used in HSS utilize a much slower and gentler heat source (up to 10,000 times slower), lasers are much hotter and include faster changes in temperature.
Hopkinson says the long view is that, at least for some parts and geometries, HSS will easily compete with injection molding and CNC machining.
"We're beginning to find some geometries where we expect it to be cheaper to use HSS than to injection mold for any production volume. It's been the case that it's only cheaper to additive manufacture a product up to a certain production volume, thereafter it's cheaper to injection mold," Hopkinson says. "But we've found – for some geometries – this is no longer the case. With HSS, we predict for a substantial range of products it will always be cheaper than injection molding, which won't be able to compete on cost in these cases. We think this is a very profound first for additive manufacturing."