May 25, 2017 | By Tess

A team of researchers from the Lawrence Livermore National Laboratory (LLNL) says it has developed a new and faster method for 3D printing metal objects. Called Diode-based Additive Manufacturing (DiAM), the process is reportedly capable of printing “faster than ever” thanks to an OALV technology originally developed for the National Ignition Facility (NIF).

The research, which was recently published in the journal Optics Express, shows how the LLNL team was able to adapt a technology originally developed for patterning and smoothing high-powered laser beams for the NIF to be used for metal 3D printing.

Diode-based Additive Manufacturing uses a set of four diode laser arrays and a pulsed laser​ to 3D print metal objects

The new 3D printing method, DiAM, utilizes “high-powered arrays of laser diodes” in combination with a laser modulator made for the NIF to “flash print” an entire layer of metal powder at once. This method, in contrast to the raster scanning method that most selective laser melting (SLM) printers use, allows for a much faster rate of additive manufacturing.

The researchers also added that the technology is well suited for rapidly printing large-scale metal objects, and offers a higher degree of design flexibility than existing SLM 3D printing systems.

"By cutting the print time and having the ability to upscale, this process could revolutionize metal additive manufacturing," commented Ibo Matthews, an LLNL scientist and the paper's lead author. “The speed, we estimate, is a one cubic meter build that would normally take 10 years to make could be done in a matter of weeks, because you can image the whole thing at once.”

He notes that the added capability of printing layer by layer can also help to reduce residual stress in the 3D printed metal object because “you can have the laser light coming through only where it's needed.”

(Images: Kate Hunts / LLNL)

What sets the new metal 3D printing process apart is its Optically Addressable Light Valve (OALV), a customized laser modulator that uses a liquid crystal cell and photoconductive crystal. Originally developed for the NIF’s Laser Energy Optimization by Precision Adjustments to the Radiant Distribution (LEOPARD) system, the OALV can be used to “dynamically sculpt” the high-power laser light based on pre-programmed images (i.e. the 3D model).

In this way, the device is similar to liquid crystal-based projectors, only it can be used for higher laser powers because it is unpixelated. It was James DeMuth, a former LLNL researcher who discovered that the OALV technology used for NIF could have applications for 3D printing.

"The DiAM project marries two technologies that we've pioneered at the Lab: high-power laser diode arrays and the OALV," said John Heebner, an LLNL scientist that led the OALV’s development. "Given that we put all this time and development into this light valve, it became a natural extension to apply it to this project. We went through some calculations and it was clear from the outset that it would work (with 3D printing).”

According to the researchers, the new 3D printing technique not only has the capacity to build larger-scale parts, but can produce a higher imaging quality than existing 3D printers. Additionally, the OALV can be used to fine-tune gradients in the projected image which can also cut back on residual stress.

To demonstrate the innovative process, the LLNL research team used a tin powder material to produce two small metal parts: an impeller (a small turbine blade) and the LLNL logo. The lab says the new printing technology will open up doors for faster, bigger, and even cheaper metal 3D printing.

 

 

Posted in 3D Printing Technology

 

 

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