How Efficient is Metal Additive Manufacturing?

Structurally optimized wheel bearing for an ultralightweight vehicle designed for Additive Manufacturing – made in the 3D-Printing Lab for Metals and Structural Materials at Fraunhofer EMI. (Image courtesy of Fraunhofer EMI.)

The 3D-Printing Lab for Metals and Structural Materials at Fraunhofer EMI houses one of the largest commercially available 3D printers for metal currently available. Using selective laser melting (SLM), the printer can produce metal structures with dimensions of up to 40cm.

Fraunhofer researchers are now combining additive manufacturing with intelligent lightweight design in an effort to maximize resource efficiency in manufacturing. More specifically, the researchers in the 3D-Printing Lab investigated just how economical the metal additive manufacturing process is in terms of resources, and whether material and operating costs can be minimized compared to conventional subtractive processes.

To do this, they took a practical, widespread component for their tests: a wheel carrier such as might be used in a lightweight vehicle. “We were able to quantify the effect lightweight construction – and specifically the use of structural optimization methods – has on the resources used in the SLM manufacturing process,” said Klaus Hoschke, scientist and group leader at Fraunhofer EMI. The focus was on energy and material consumption, manufacturing time and the CO₂ emissions that arise during small-scale production of twelve wheel bearings.

Resource Efficiency on Short Runs

After the researchers used the numerical finite element method (FEM) to simulate and analyze a draft design and determine the right geometric shape through structural optimization, they constructed the wheel bearing in an optimized lightweight design. The result was a wheel bearing designed for the defined load scenarios and offering maximum performance. Because of their geometric complexity, structures produced in this way cannot be manufactured by conventional methods such as milling or turning.

Finite element analysis of the start design of a wheel bearing technology demonstrator (left); numerical design optimization of the technology demonstrator to reduce the component’s mass without impairing functionality (center); and CAD template for manufacturing the 3D metal component (right). (Image courtesy of Fraunhofer EMI.)

“With the lighter model, we were able to save hugely on resources during production, as less material has to be produced per component,” said Hoschke. “If you multiply this by the number of units in a small-scale run, then you require less time, material and energy for manufacturing. Reducing volume through the use of higher-strength materials offers the greatest potential for energy savings here.”

Using the numerically optimized version of the wheel bearing, 15 percent less energy was required for the additive process than for the conventional method: 12kWh for the conventional design vs. 10 kWh for the numerically optimized design. In each case, the measured value refers to a series-manufactured component. Manufacturing time was cut by 14 percent and CO2 emissions by 19 percent. Most impressively, material consumption was reduced by 28 percent.

Additive Manufacturing Efficiency

Although structure-optimizing algorithms and numerical optimization simulations are already being employed for 3D printing of components today, they are only used when the component must be extremely lightweight, such as aircraft parts designed to reduce fuel consumption during operation.

However, the results of the small-scale series production of the wheel bearing suggest that additive manufacturing can also be useful when a component does not have to be structurally optimized as such.

Several structural components arranged on a base plate after a selective laser melting process. (Image courtesy of Fraunhofer EMI.)

“A heat exchanger or a tool mold, for example, do not have to be lightweight to improve their functionality. Nevertheless, it makes sense to design them with reduced weight and volume when manufacturing them additively, because this way you can bring down manufacturing costs,” explained Hoschke.

In the future, Hoschke and his team want to research the extent to which other design heights, series sizes and materials such as titanium affect the resource efficiency of the manufacturing process.

For more advancements in additive manufacturing, check out Cold Spray Additive Offers New Fabrication Process for Permanent Magnets.