Which Tech Will Dominate 3D Printing?

As 3D printing, also called additive manufacturing, is increasingly becoming a key component of advanced manufacturing, it is important to further

3D printing, also known as additive manufacturing, is rapidly becoming a crucial component of advanced manufacturing processes. As 3D-printed parts and components are frequently utilized in highly demanding applications, such as automotive engines, rockets, and military equipment, any failure in a single component can have catastrophic consequences.

To mitigate this risk and pave the way for 3D printing to become the dominant manufacturing method, surpassing traditional techniques like melting metal in casts and machining, continuous optimization of the 3D printing process is paramount.

Among the various 3D printing techniques, laser powder bed fusion is particularly suited for precision manufacturing. Researchers at the University of Wisconsin-Madison and Argonne National Laboratory have recently employed advanced X-ray imaging to analyze this process meticulously, uncovering promising avenues to drastically reduce defects during manufacturing. Their findings were published in the International Journal of Machine Tools and Manufacture, under the title “Revealing mechanisms of processing defect mitigation in laser powder bed fusion via shaped beams using high-speed X-ray imaging”.

The Mechanics of Laser Powder Bed Fusion

In powder bed 3D printing, a layer of powder containing the material used for additive manufacturing is spread out in a container. A laser then selectively melts/fuses the powder in the zone that will eventually form the 3D-printed item.

Following this, another layer of powder is deposited on top, and the portions that need to be melted and added to the item are once again targeted by the laser. By repeating this process over time, even highly complex shapes and relatively large items can be produced.

You can observe laser powder bed fusion in action in this video, along with examples of items that can be made using this technique.

This method is not limited to plastics; it can also be used to create items made of metals, including titanium, steel, cobalt-chromium, aluminum, and more.

The advantages of this method lie in its ability to create precise geometry, with tolerances of +/- 0.2mm, which are comparable to metal injection molding, and its efficiency in material usage, as the unused powder can be collected back and reused.

Moreover, by simultaneously using multiple lasers, which is typically found in more advanced 3D printer designs, larger parts can be printed quickly.

It's important to note that laser powder bed fusion encompasses several sub-techniques, including:

Revealing Mechanisms to Prevent 3D Printing Failures

In theory, additive manufacturing of metal parts should yield results equivalent to those obtained from traditional casted parts. However, in practice, issues can arise, such as pores, or “voids,” on the surfaces, and large spatters.

Such structural imperfections can lead to the parts breaking, which is unacceptable in critical applications.

“Because we understood the underlying mechanisms, we could more quickly identify the right processing conditions to produce high-quality parts using the ring-shaped beam.”

Lianyi Chen – Associate professor of mechanical engineering at UW-Madison

The Ring-Shaped Laser Beam

The first modification made by the researchers to their 3D printing setup was to replace the standard laser beam with a ring-shaped laser beam, which was provided by nLight, a laser company specializing in semiconductor lasers.

This distinct shape facilitates better circulation of the melted metal within the melt pool overall and results in smaller waves on the surface of the freshly created item, reducing the size and distance traveled by the spatters.

Matching Model And Observations

The researchers went on to verify these observations using the high-energy synchrotron X-ray facility at Argonne National Laboratory. They employed this facility to capture high-speed snapshots of the 3D printing process, which allowed them to check whether their mathematical model accurately simulated reality.

3D Printing At A Quicker Pace

Another achievement was the ability of the ring-shaped beam to penetrate deeper into the powder without causing more instability. This led to thicker layers without compromising the strength of the finished product.

As the production ultimately requires fewer layers, this speeds up manufacturing and increases the overall productivity of the machine.

An Example of Powder Bed Fusion in Practice

This line of work is far from being merely an academic demonstration; it has the potential to directly improve powder bed fusion machinery already used in the industry.

A prime example would be in aeronautics, with the fuel nozzle on General Electric’s GE9X engine, which is used on Boeing 777 aircraft.

The GE9X is the largest turbo-fan engine produced, and the additively manufactured nozzle is five times more durable than previous versions.

It's worth noting that such developments are still very recent, with the GE9X design being approved by the FAA in 2020.

Even a higher quality powder bed fusion process, as well as a quicker one, could improve the design further while at the same time reducing its costs.

The Future of 3D Printing: Advanced Manufacturing Domination

We have previously covered how 3D Printing is consolidating into the future of manufacturing.

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