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Lawrence Livermore National Laboratory Announces New 3D Metal Printing Method
#SIU_news 2017-04-28 00:00:00
The US Federal Research Laboratory, Livermore National Laboratory (LLNL), announced the results of a three-year research project on 3D printing using metal. A technology called Direct Metal Writing (DMW) complements existing metal printing solutions, such as selective laser fusion (SLM). The technology was developed in collaboration with the Worcester Polytechnic Institute, Massachusetts.
In contrast to selective laser melting, direct metal printing eliminates the need for high-power lasers for sintering metal and forming three-dimensional structures. Researchers believe that their new development has advantages over the more traditional methods of manufacturing metal parts in 3D printing in terms of the reliability of the parts produced.
The new approach uses a semi-solid metal raw material, such as a heated ingot or a small metal block. After heating to a semi-solid state, the metal is pushed through the extruder and brought to a pasty consistency. The material has a shear thinning, which means that it turns into a solid, if left motionless, and becomes a viscous fluid when moving or when a force is applied.
The University of Sheffield is similarly studying alternative 3D printing methods using metals, but their approach is to increase the number of lasers to accelerate this approach.
LLNL engineer Andy Pascall, explains the DMW process:
You need precise temperature control. It matters how to stir, how to quickly stir and so on. If you can get plastic properties, then you are doing everything right. What we did was understand how metal can flow through a nozzle. Now we have reached such a level of control that we can print self-supporting structures. It was impossible to think of such things before.
Overcoming SLM Technology Challenges
The lab explains that this new technology can overcome some of the problems that SLM faces, in particular with respect to porosity or the creation of parts with deformations or gaps. Researchers also claim that this approach can significantly reduce the need for a thorough analysis of 3D printed parts. DMW is currently working with bismuth-tin material and still needs to be tested and refined before it can be used for industrial materials such as titanium and aluminum. The bismuth-tin mixture has a low melting point and, therefore, is easier to use with this technique. However, according to the laboratory, they have already begun working with aluminum materials.
Staff scientist Luke Thornley, who worked on material science in this project, explains the importance of DMW:
Most of the work that goes into checking and analyzing defects will be eliminated. We can use less material for the manufacture of parts, that is, to create lighter parts, which would be very significant for the aerospace industry.
The impact of metal powder on the market
DMW technology developed by Lawrence Livermore National Laboratory eliminates the need for metal powders. The market for metal powders is becoming increasingly competitive. Canadian company PyroGenesis has recently returned to the market to meet the high demand for 3D printing materials.
While direct printing using DMW metal is promising, it has a long way to go before it can replace SLM technology with metal powder and enter the dynamically growing market of metal powder. The 3D Printing Industry has just visited Metalysis, a UK-based powder manufacturer, to open its new research center in South Yorkshire.
Lead author of the study, material scientist Wen Chen, says:
We are in a new territory: we have developed a new technology for the production of metal additives, which people still do not know about. I think that many people will be interested in continuing to work in this direction and extending the discoveries to other alloys.
Applied Physics Letters published an article entitled “Direct Printing Method Using Metal: Rheology Control Through a Microstructure”.
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