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University of Waterloo researchers are keeping their eyes on the prize as they work to advance industrial adoption of metal 3D printing.

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Reactions are remarkably predictable when I show visitors a small metal object we recently designed and printed in 15 hours and for about $350 in our newly expanded additive manufacturing (AM) lab at the University of Waterloo.

Approximately the size of a baseball, it consists of four hollow, free-floating spheres of descending size, the three smallest ones all housed within another, their thin, strong walls fashioned from a nickel-based alloy in a lattice structure of hexagonal shapes.

It immediately brings to mind those centuries- old nesting boxes of Chinese origin, but this object is brand new, unmistakably a product of the here and now.

Including internal support posts that were easily removed in post-production, it was made as a single piece using the layer-by-layer technique at the heart of 3D printing. It has no lids or seams and almost certainly couldn’t be replicated, with such a high degree of quality, by any other means.

So what do people say about this object? ‘Wow.’ People always say ‘wow.’

Turning it over in their hands as the intricate spheres within spheres freely tumble and clink, even newcomers to AM can begin to see the enormous potential, the promise, of technology that will transform the entire manufacturing enterprise, the very way we make things, in the next 10 to 15 years.

What they recognize so clearly in that metal object is what those of us on the front lines of AM research and development describe as free complexity. If you can imagine it, industrial 3D printing offers a way to make it, unfettered by the compromises of traditional manufacturing methods.

And in addition to almost limitless design freedom in terms of geometry, AM allows a one-piece part to be made from two or more functionally graded materials to optimize performance and increase productivity.

An injection mold for the plastics industry, for instance, is now typically constructed entirely of tool steel to provide the wear durability required for constant, repetitive use. With AM, however, it is possible to make the surface of that mold out of tool steel and the rest of it from copper.

Since copper has much higher thermal conductivity than tool steel, that means the mold can be cooled faster and with less energy, reducing the time and cost required to make each plastic part.

In addition, industrial 3D printing allows the production of molds with cooling channels that conform to the contours of their cavities, or acting surfaces, speeding the cooling process even more versus standard channels that are limited by machining to linear geometry.

Reports out of Germany suggest the use of molds combining functionally graded materials and conformal cooling channels can boost injection molding productivity by up to 125 percent. Wow, indeed.

Another key AM benefit, a special area of interest for experts at our Waterloo facility, involves sensors that can be embedded in parts during the printing process so that they are near the surface, but still protected by the metal shaped around them.

This technology has vast potential, for instance, in the oil and gas industry, where distributed optical sensors in massive drill bits could provide real-time data on variables such as temperature and cutting forces during work on new wells.

That information would provide instant insight on the geology of a drilling site and enable adaptive control of operations, informing decisions such as whether to increase or decrease the speed of a bit to improve its performance at a particular depth.

Also of great promise, especially in relation to extremely expensive parts in the aerospace and automotive industries, is the use of AM to make repairs rather than replace worn, broken or flawed parts, minimizing both production downtime and costs.

It occasionally happens, for instance, that huge automotive molds reveal imperfections once pressed into service. Instead of scrapping them and absorbing losses in the millions, salvage at a fraction of the cost may be possible using laser 3D printing to selectively add material with far superior properties than conventional welding.

All of those benefits and more – less material waste, energy savings, rapid prototyping, shorter time to market, the ability to make parts that are no longer in commercial production from their old CAD models – are now fueling both expectations and investment in AM around the world.

But what guests at our Waterloo lab can’t see as they marvel at those metal spheres within spheres is that there are still numerous challenges to overcome before AM fully realizes its potential.

Chief among them in our primary field of metals and metal alloys is a severe shortage of powders that have been validated for use with metal 3D printers, including laser, electron beam and binder-based AM processes.

Take steel, for example. There are currently more than 1,000 steel alloys commercially available for conventional casting, but just seven that have been verified for AM production by original equipment manufacturers (OEMs). In the case of aluminum alloys, the ratio is about 600 to 12.

Getting more AM metal powders on the market, one of our research thrusts in Waterloo, will take years of work. In the meantime, unfortunately, the shortage limits the number of parts that can be made and companies that can benefit from the technology.

In addition, the relatively few metal AM powders that are for sale cost five to 10 times more than raw materials for casting, machining and other traditional forms of manufacturing.

Part of that problem is a lack of competition among suppliers. Another is low volume, with worldwide sales of metal 3D printing materials totalling less than $400 million a year, a tiny fraction of the overall raw materials market.

In time, and as the adoption of AM picks up steam, prices are expected to fall dramatically. As with most challenges, this one creates opportunities to improve powder production methods and, quite possibly, formulate entirely new powders to get the most out metal 3D printing.

Opportunities also exist in the field of computer modelling of both AM machines and AM processes to improve production via reliable and validated simulation rather than costly experimentation. Very few models have been developed to date, adding research and development costs to high material costs as deterrents for companies that might otherwise move into AM.

Although the technology has already produced some impressive results, it is also true that reliability and repeatability – in effect, producing parts of consistently high quality – is still a significant AM problem, particularly for mass production. Failure rates for many applications remain in what we call the ‘red zone,’ where using the technology simply isn’t economically justifiable.

The underlying problem is that additive manufacturing is so sensitive to both environmental and process disturbances – from fluctuating temperature and humidity levels, to non-uniform powder sizes – a given part might be perfect one day and of such low quality that it’s garbage the next.

Completely controlling processes and the environment is virtually impossible, so our researchers are focused on solutions that employ innovative sensors to monitor conditions and quality control algorithms to automatically adjust process parameters, such as laser power or process speed, to compensate for disturbances instead.

We like to think of this closed-loop control technology as the AM equivalent of the self-driving car of the near future.

And while we are fully aware of the considerable challenges – including the need to coordinate expertise in different areas so AM can be applied to make specific parts – we are confident it is only a matter of ‘when,’ not ‘if,’ they will be conquered.

Those metal spheres that never fail to impress our guests represent an extraordinarily valuable prize. We’re not taking our eyes off of it.

Dr. Ehsan Toyserkani is a professor of mechanical and mechatronics engineering at the University of Waterloo in Waterloo, Ontario, where he holds the University Research Chair in Additive Manufacturing. His research lab, the Multi-Scale Additive Manufacturing (MSAM) Laboratory, is the largest AM facility in Canada and one of the top 10 academic AM facilities in the world.

With more than 17 years of experience in AM research and development, including mechatronics AM systems and AM applications in medicine and engineering, Dr. Toyserkani has six granted or pending patents on monitoring and real-time control of laser AM, AM technologies for embedding optical sensors within metallic structures and AM of porous structures.

Volume:
20
Issue:
3
Year:
2017


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