Nov.5, 2014 | By Alec

As most of you will know, the 3D printing community largely relies on FDM desktop 3D printers that can print objects in a variety of plastic filaments. While great fun and very useful for prototyping and design, this technology largely lacks the potential to create actually marketable products. Plastic objects just aren't sturdy and detailed enough, which forms a large barrier for this exciting additive manufacturing technology.

Those 3D printing companies focusing on consumable products therefore tend to rely on metal printing, but that too comes with a few downsides. Metal 3D Printing is the process by which parts are manufactured by a laser fusing together high performance metals, layer by layer. This technology, called selective laser sintering (also known as SLS 3D printing), is capable of producing very detailed results, but there are some unfortunate problems inherent to these powdered metals.

For these naturally contain oxides, which limits the metal's inherent strength in durability. It might be best to regard them as tiny bubbles in the material that make the structure less sound, just as bubbles in dough or concrete would do. As Dr. Dirian Apelian, professor of mechanical engineering at the Worcester Polytechnic Institute in Massachusetts, stated:

That's a very bad thing. It would be like having little pin holes in a glass pane, adding lots of places where the glass could break. The powders for these high-temperature melting alloys are difficult to make and they have a lot of oxides, so it may not be as strong and may lead to failures.

Other downsides inherent to metal 3D printing are a lack of quality and variety: there are only a few alloys that are both suitable for SLS 3D printing and available in sufficient quantities. As James Bredt, a co-founder of Viridis 3D, which specializes in this technology said: 'It's a small market. The manufacturers of these metal powders are huge companies making the powders for different industries. Most don't really work on these laser machines. They're not set up to produce stuff of purity as high as you need for a laser sintering process.'

All this is what's been inspiring a brand-new scientific initiative by Dr. Apelian, in collaboration with researchers from the Lawrence Livermore National Laboratory and Viridis 3D, a 3D printing specialist company based in Woburn, Massachussetts.

Dr. Dirian Apelian, head of the research team

Together, they are researching the use of so-called semi-solid metals that can be extruded, rather than lasered. These exciting new metal material could overcome all the problems associated with metal 3D printing, and could thus easily revolutionize the 3D printing industry.

Hopefully, these will result in stronger and sturdier 3D printed objects that will last longer. These materials will have a somewhat gooey or mushy consistency, and reporters from Computer World already noted that this could have a variety of medical, automobile and aeronautic 3D printing applications.

This new method of metal printing is also accompanied by another crucial advantage: lower energy costs, and thus lower overall costs. As one scientist from Viridis told reporters, 'If you're using lasers [and thus powders], you have to get the material up to white heat to get the materials to fuse together. A lower temperature means less energy is needed to make the part and that's a significant part of the cost… One of the significant costs of the process now isn't significant anymore.'

Dr. Apelian went on to speculate about the newer possibilities this material brings to the table. For one, this technology will be able to work a wider range of metals – specifically the superalloys – which are suitable for things like medical implants or military components:

Everyone has different-sized knees. If they could print a new [customized] knee for someone then it would fit just right and there would be less pain and less physical therapy. There are a lot of applications where you're not making 100,000 parts for automobiles. You may be making customized pieces where it's maybe one or two or four of them. These are high-integrity applications, like jet engine parts or legacy parts that nobody makes anymore. It will revolutionize the way we make things that are customized.

However, controlling semi-solid metals isn't as easy as extruding basic plastic FDM filament. As the professor speculated, 'How do you control gooey, mushy metals so you have high precision when you make the deposit? I have to control the thixotropy or how the flow changes under the application of a force. I have to make sure it's flowing in a controlled manner.'

Apelian stated that they are probably a year-and-a-half away from actually using semi-solids in a testing environment, so it will be some time before this revolutionary concept can be applied in a marketable fashion. 'We're not doing any printing yet until we know what we're doing,' he added. 'When I understand what's going on, then I'll print. I want to know what the issues are and figure it out and then I'll go work on it. It's all the prep work ahead of time.'

The whole concept of gooey metals that can be printed in a vaguely FDM-like fashion is nonetheless very interesting and comes with a host of marketable options. As Joe Kempton, an analyst for market research firm Canalys remarked: 'It's quite interesting. Perhaps one of the biggest obstacles for 3D printing itself is the limited amount of materials you can print with… What they really want is a wide range of high-performance alloys or superalloys. The reason these industries are looking for superalloys is because they often have extreme durability and high performance under pressure. They're resistant to oxidation and corrosion.'

Its very nature thus makes it a promising technology for a number of industries, like the automobile and aerospace industries. While it still comes with a host of questions, such as prices, applicability and flexibility, 3D printable metal semi-solids could thus be a real game-changer in the world of 3D printing.


Posted in 3D Printing Technology

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