Analysis and interview published in October 2022. Roles, configurations and applications reflect that period. The arguments are opportunities to measure, not a life-cycle assessment demonstrating an environmental advantage.
While we take great care not to use the buzzword “sustainability” without key data, we do recognize that it will take time for OEMs and AM users to provide quantitative analysis that demonstrates how efficient AM technology aligns with a “sustainability vision” that takes into account the “triple bottom line” we highlighted in various ways in the September/October 2022 edition of 3D ADEPT Mag. What we can do though, is to highlight the arguments that would play to the strengths of manufacturers’ technologies, arguments they may focus on, to deep dive into this much-needed quantitative analysis. This is what this article ambitions to explore with a key focus on Large-Scale Additive Manufacturing, short for LSAM.
Developed by Thermwood in Indiana, LSAM uses polymer pellets, including short-fibre-reinforced materials. It deposits large beads of molten material in a room-temperature environment. “Continuous cooling” refers to controlling the temperature of the deposited layer before the next one; the polymer is still heated for extrusion. The approach targets large near-net-shape parts, machined afterwards where required. At the time of this 2022 article, Thermwood had been developing it for more than five years.
Over time, we witnessed the possibilities of Thermwood’s Large Scale Additive Manufacturing and we saw the development of new approaches and features such as the Vertical Layer Print (VLP) technology or the thermal sensor, that aim all to improve the manufacturing processes with these machines. “LSAM is a tool that when yielded by a skilled craftsman, can produce items not originally considered for the technology. Prototyping of large components is of particular interest as of late. [However], Collaboration with industry to showcase what is achievable with Large Scale Additive is paramount in effectively getting the information across to the right people” Jim Bullis, then VP of Sales at Thermwood, told 3D ADEPT Media.
Manufacturers seek to reduce costs and resource use. Assessing LSAM’s contribution requires examining the operations avoided, those added and the performance of the resulting part.
The sustainability performance indicators
There are currently various principles of sustainability that are explored and adopted in manufacturing. At 3D ADEPT, we believe that it should be a continuous journey where organizations should commit to focusing as much on social and environmental concerns as they do on profits (economic) hence the triple bottom line profit, people and planet. This journey doesn’t have to be taken in the rush. For many organizations, each of these bottom lines includes various categories and sometimes sub-categories that may serve as indicators of where to improve processes.
The diagram groups areas including materials, energy, emissions, transport, costs and social conditions. Improvement in one indicator can come with a trade-off in another: these dimensions should be assessed together. The diagram is a framework for discussion, not certification of LSAM.
Arguments to examine for LSAM
AM can facilitate production near the point of use. A shorter supply chain may reduce some transport, but the overall result also depends on material sourcing, electricity, equipment utilisation and volumes. Decentralisation alone therefore does not ensure a lower environmental impact.
The first argument is combining printing and machining. In the relevant LSAM configurations, printing produces a near-net-shape blank; CNC machining then achieves the required dimensions and surface finish. This combination addresses part requirements without extending the limitations of one process to all AM.
Simply put, after the 3D printing process of the part, it is trimmed to its exact desired size and shape using a CNC router. “The LSAM can perform both the “additive” and “subtractive” functions on the same machine. This approach, called “Near-Net shape”, uses carbon fiber reinforced thermoplastic material to quickly create a part that is nearly, but not exactly, the final net shape. The “subtractive” function then machines the part to the exact final net shape”, Dennis Palmer, Former Vice President of Sales at Thermwood once told 3D ADEPT Media.
Combining the operations can reduce transfers and repeated setups. Economic benefits still need calculation against configuration, floor space, cycle times, material machined away and utilisation. Integration does not automatically guarantee a better return on investment.
Machining and manufacturing skills can help with adopting this equipment. They need to be complemented by training in design for AM, materials, safety and process control. This transfer of skills concerns the social dimension of the assessment.
The second argument concerns recycled materials. According to Thermwood, LSAM can process certain recycled composite pellet formulations. Compatibility, consistency and properties need verification for the application. Recycled feedstock may reduce virgin material use, but preparation, drying, losses and recycling cycles affect the outcome; a lower carbon footprint cannot be inferred from this choice alone.
As a matter of fact, “recycled materials are currently being used in a variety of LSAM 3D printed applications”, Bullis notes. “Some of the complexities related to getting past prior experiments that may not have proven successful. Material producers are continuously working to develop new formulations. LSAM allows for owners/users to work directly with material producers to develop novel formulations that may provide a competitive edge. Users are not “handcuffed” to any particular material provider, this allows them to be more competitive”, he adds, speaking of the complexities in the utilization of FRP composite 3D printing.
A reduced number of processing steps. We see the ability to manufacture in one “piece” as a sustainable performance indicator as most manufacturing processes often require several processing steps and sometimes multiple machines to achieve the final part. “The LSAM flagship model can be up to 100’ long and 15’ wide” (approximately 30.48 m × 4.57 m) Bullis recalls. Being able to use an LSAM machine to create parts in their entirety may result in the reduction of energy needs, can also reflect on other cost considerations or categories.
These are the dimensions quoted by the speaker for a large configuration, not every model. Reducing assembly can avoid some operations; energy savings need measurement across the complete chain, including extrusion, machining and waste handling.
Thermwood describes the configurations and cooling process in its technical documentation; its 2021 announcement details the introduction of 15-foot-wide tables.
These arguments are the start of a much deeper conversation that we hope to continue with Thermwood moving forward. Indeed, while we want to educate and highlight the sustainable performance indicators that may result from the integration of LSAM into production environments, we also want to warn on these seemingly obvious benefits that AM might introduce which often result in faulty implications for the “green” credentials of the technology.
This article forms part of the discussion in the September/October 2022 issue of 3D ADEPT Mag.
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