Manufacturing | Article

Rethinking the Supply Chain for Additive Manufacturing

The impact on materials, post-processing, and efficiency is substantial.

Written by: Adam Kimmel

Additive manufacturing (AM) has caused design and process engineers to reevaluate how they turn a concept into a production-ready component. AM decreases the fabrication cycle time, and soon, the takt time becomes limited by the ability to procure the necessary material to fill the production pipeline. As a result, there are two areas in which AM has affected supply chain: raw material and post-processing.

Raw material

Dr. Ankit Saharan, manager, R&D and applications development at EOS North America, sees the supply chain as a critical driver to grow additive manufacturing. “From our point of view, the materials side of the additive manufacturing equation holds the most potential for the future growth of the overall technology,” he says.

Developers introduce new materials to the market each year. For example, EOS recently announced a new suite of materials from titanium grades to aluminum for use in AM applications.

For any AM-capable material, from metal to polymer powders, the logistics around procuring raw material for a 3D printer is the same as traditional manufacturing processes. To achieve peak efficiency from just-in-time fabrication, companies using both styles of manufacturing must define the quantity and supplier base for the feedstock materials to support production volumes.

“However, where we do see additive manufacturing changing the supply chain is that you can significantly reduce the need for large inventories of finished parts,” Saharan says. “We are seeing this with automotive suppliers and also within aerospace, where instead of needing an extensive stockpile and sophisticated supply chain, you have an additive manufacturing system at your service center that can quickly print a needed part.”

He noted a European case study in which Daimler EvoBus, an EOS customer, implemented additive manufacturing and integrated the process into its supply chain for inventory components. EvoBus identified 35 metal and polymer components for process substitution to additive manufacturing. Because AM adds material to itself to manufacture the parts (instead of being cut out of raw material), reverse engineering yielded insight into AM processing opportunities. For example, the team found that polymer PA2200 could withstand automotive flame protection requirements. Further insight into the specific fabrication process could allow EvoBus to create the parts on location at its customer’s facility.

The flexibility of AM changes how manufacturers approach managing spare parts. As subtractive manufacturing requires orders of specific sizes of raw material, the tendency by procurement groups is to ensure there is always more material than needed to maintain production rates. AM can form its raw material into various shapes, thicknesses and designs so that the procurement group can order material much closer to just-in-time. Companies have even begun running inventories to zero to save storage and move to deadline-driven product schedules. Furthermore, the digital file that contains all critical geometric information enables the manufacturer to repair and replace a part regardless of its manufacture date, supporting this shift to procurement strategy.

The materials side of the additive manufacturing equation holds the most potential for the future growth of the overall technology.
Dr. Ankit Saharan EOS North America

Post-processing

A common myth about AM is that once the printer finishes construction, the part comes out ready to go. In reality, post-processing is the second macro step in the fabrication process and introduces significant variations to the supply chain.

Conventional AM post-processing techniques that are not present in traditional manufacturing include the following: stress relief from the thermal cycling during construction, removal of the part from the build plate and sacrificial lattice support structure removal.

Many of these processes require additional capital equipment, and subsequent management and repair. While traditional manufacturing starts with material that exhibits the desired properties and cuts out the desired shapes, AM begins with the desired shape and is treated to enhance the material properties post-process.

Special furnaces can manage the environment around the part to minimize oxidation and regulate temperature. Removing the part from the build plate uses means ranging from a bandsaw to a wire electrical discharge machining (EDM) operation, depending on the part requirements.

Removal of the lower-density lattice support structures has proven to be an opportunity. In contrast, drilling and similar methods have shown inconsistent results. This process gap is an opportunity for further AM-fueled disruption in the supply chain.

Real-world results

Lockheed Martin found success when modifying its supply chain to suit AM for its aerospace products. Using expensive alloys such as titanium, the company wanted to minimize its raw material buy as much as possible. Lockheed Martin defined a buy-to-fly ratio (similar to well-to-wheel), which compares the mass of raw material input into the process to the mass of the final part output.

One of the targeted subcomponents was the bleed air-leak detect bracket, which had a buy-to-fly ratio of 33:1 via traditional (subtractive) manufacturing. By employing additive manufacturing, Lockheed Martin realized greater than 50% material savings and reduced its buy-to-fly ratio to nearly 1:1.

This example supports the movement toward additive manufacturing and encourages procurement managers to consider changing the supply chain to this transformative, disruptive technology—especially given the high amount of innovation occurring in the field.

Click here to learn more about ASME's new course, "Design for Additive Manufacturing with Metals."