Obsolete components, long-lead replacements and spares needed in small numbers are useful starting points for on-site 3D printing. Where conventional supply is difficult, additive manufacturing can offer another way to obtain a replacement, with local production bringing that capability closer to the equipment it supports.
The strongest candidates combine a clear supply problem with a material, design and service duty that the available process can meet. Four areas guide the initial assessment: material, function, demand and inspection. Hyperion works with organisations to assess candidate applications and explore whether production at the operational site, a regional hub or a specialist facility could suit their needs.
Start with the material and its operating conditions
Material selection begins with what the component must withstand: loads, temperature, chemicals, moisture, sunlight or repeated contact with other surfaces. A printable material must deliver the properties needed for that duty in the finished component.
Polymer housings, covers, ducts and spacers can be worth investigating where their service conditions suit the material and process. Metal parts require a separate assessment of the alloy, manufacturing route and any heat treatment or machining. Substituting a material also requires checking its effect on the component’s performance and compatibility with the surrounding equipment.
Published research demonstrates the potential for wire arc additive manufacturing (WAAM) to produce useful engineering properties. In a comparison of WAAM and cast 316-series stainless steel, the WAAM samples achieved higher yield strength, while the heat-treated cast sample performed best for wear resistance. Corrosion resistance also varied with the WAAM production conditions. [1] These results show why material selection should focus on the properties that matter to the component’s duty.
Check function, geometry and finishing
A replacement must fit its interfaces and perform its intended function. This makes dimensions, tolerances, surface finish and the consequences of failure part of the assessment from the outset. A lightly loaded component can still perform an important protective or operational role.
The available process also affects what can be made. Part size, wall thickness, overhangs and access for finishing can influence the build strategy or require design changes. Mating faces, holes and sealing surfaces may need machining after printing. Any redesign must preserve the required fit and function and be approved for the intended use.
A study undertaken at BAE Systems Hägglunds successfully demonstrated a WAAM build of a redesigned obsolete component previously made by casting. Adapting the geometry and deposition strategy allowed the part to be built using available in-house equipment, demonstrating a potential alternative for a component needed in very small quantities.
Active deposition took approximately five hours, with cooling and handling bringing production time to approximately eleven hours. These were build times for the experimental component; machining of functional surfaces and full qualification for operational use remained outside the completed work. [2]
Which spare parts are worth printing on demand?
Maintenance and purchasing records help establish where an alternative supply route could create the most value. Look at how often a part is needed, how long it takes to obtain, minimum order quantities and what happens when it is unavailable. This connects the technical shortlist to the operation’s actual costs and priorities.
Compare the cost and time to obtain a usable replacement through each route. For additive manufacturing, this includes design preparation, material, production, finishing, inspection and any required testing or approval. For existing supply, consider purchase price, freight, lead time, stockholding and the operational consequences of waiting.
A study of an aluminium component found lower modelled production costs for a route combining wire-arc deposition, milling and sheet forming than for die casting or machining from solid. Avoiding dedicated moulds and reducing material waste contributed to the advantage. [3] The result illustrates two sources of potential savings to investigate when comparing production routes, alongside the engineering and approval work needed for the replacement.
Demand also needs to justify the preparation. A rarely used component may be worth developing if its absence has major consequences, while an inexpensive spare with reliable supply may be better purchased conventionally. For on-site equipment, the business case should consider the wider production workload as well as individual parts.
How are printed spare parts inspected and qualified?
Before production, agree what the replacement must demonstrate and who will approve it for use. This gives the team a clear basis for choosing the material, setting up production and checking the finished part.
For a straightforward component, the checks may focus on dimensions, fit and function. More demanding applications can require material data, controlled production parameters, additional testing and documented engineering approval. Finished-part inspection forms part of that evidence, alongside the design assessment and records of how the part was made.
Some activities can be completed locally; others may require a specialist facility. Off-site testing does not automatically rule out on-site production, but its cost, transport and turnaround time belong in the plan. These arrangements should be included when comparing production locations.
What is a digital spares inventory?
A digital spares inventory brings together the information needed to reproduce selected components: controlled design files, material specifications, production settings, finishing instructions and acceptance criteria. For parts that can be produced within the required response time, it can reduce the need to keep every replacement on the shelf.
Preparing this information in advance makes repeat production more straightforward. The first replacement may require design recovery and process development; subsequent parts can use the approved design and established production and inspection instructions.
A missing CAD file does not necessarily exclude an obsolete part. Drawings, measurements or scanning can help reconstruct its geometry, but wear or damage must be accounted for. The intended design, material and service requirements still need to be established, along with permission to reproduce or modify it where required.
When does on-site production make sense?
Once a part is suitable for additive manufacturing, the next question is where to produce it. On-site production is most compelling where local availability provides a clear operational advantage and the site can support the required equipment, operators, materials and finishing activities. A regional hub or specialist facility may offer a better option where demand is limited or supporting processes are difficult to provide locally.
Hyperion’s TitanCell is a containerised large-format polymer additive manufacturing system designed for deployable production. Hyperion is separately developing its wire arc additive manufacturing capability for metal components and welcomes discussions about potential applications. The two processes have different material, equipment and production requirements.
For a fuller explanation of infrastructure, personnel and operating needs, see our accompanying article, What can containerised manufacturing offer remote operations?
Start with the spares your operation waits on
Identify the parts associated with recurring delays, obsolescence or difficult purchasing conditions. Bring whatever information is available: a drawing or sample, its function and operating environment, required quantities, current lead time and the problem with existing supply.
Talk to Hyperion about assessing your candidate spares and the production route that could suit your operation. You do not need a complete technical package to start the conversation.
References
[1] Gürol, U., Kocaman, E., Dilibal, S. and Koçak, M. (2023). A comparative study on the microstructure, mechanical properties, wear and corrosion behaviors of SS 316 austenitic stainless steels manufactured by casting and WAAM technologies. CIRP Journal of Manufacturing Science and Technology, 47, 215–227. https://doi.org/10.1016/j.cirpj.2023.10.005
[2] Strandberg, H. (2026). Evaluation of Additive Manufacturing Methods for Obsolete Components: A Comparison of WAAM, LPBF and Casting. Master’s thesis, Luleå University of Technology. Research undertaken at BAE Systems Hägglunds. See sections 4.2.4 and 5.5.
[3] Rosado, P. M. S. et al. (2026). Economic and Environmental Analysis of Hybrid Wire-Arc Additive Manufacturing with Metal Forming Operations. Sustainability, 18, 2101. https://doi.org/10.3390/su18042101
