11 min read

Additive manufacturing of spare parts: A transformation of MRO strategies

Technical analysis: Additive manufacturing of spare parts: on-demand MRO

1. Introduction: Disruptive innovation in the manufacturing industry

Additive manufacturing (AM), commonly known as 3D printing, is revolutionizing production technologies and opening up new possibilities for maintenance, repair and operations (MRO). Particularly in the area of ​​spare parts supply, AM offers the potential to fundamentally change established processes. Decentralized, demand-based production can reduce bottlenecks in global supply chains and significantly improve the ability to respond to unforeseen failures. This is crucial for the DACH manufacturing industry, which relies on high plant availability and short downtimes. Recent studies predict annual growth of AM applications in the MRO sector of over 20% through 2030, driven by technological maturity and economic benefits.

Traditional spare parts inventory is often associated with high storage costs, long capital commitments and the risk of obsolescence. For critical components, delivery times of weeks or months can lead to immense production losses, the costs of which in mechanical engineering can quickly reach EUR 5,000 to EUR 20,000 per hour. Additive manufacturing promises to overcome these challenges through a digital spare parts strategy that replaces physical inventory with digital data. This enables spare parts to be manufactured exactly when they are needed, thereby minimizing downtime and storage costs.

2. Scientific principles: materials science and process control

Additive manufacturing is based on the layer-by-layer creation of components from digital 3D models. The scientific fundamentals include a deep understanding of materials science, process thermodynamics and the mechanical properties of the resulting components. Common processes for industrial spare parts are:

  • Selective laser melting (SLM) / direct melting (DMLS): Here, metal powder (e.g. stainless steels according to DIN EN 10088, titanium alloys according to ASTM B348, nickel-based alloys according to ASTM B160) is locally melted and solidified using laser energy. The process parameters such as laser power (typically 200-500 W), scanning speed (typically 800-1200 mm/s) and layer thickness (typically 20-60 µm) are critical for the component density (up to 99.9%), the microstructure and the mechanical properties, which can often correspond to or exceed those of forged materials. Compliance with DIN EN ISO/ASTM 52907 (powder bed melting of metals) is crucial here.
  • Fused Deposition Modeling (FDM) / Fused Filament Fabrication (FFF): For polymeric materials (e.g. ABS, PLA, PEEK, PA-CF), a filament is extruded through a heated nozzle and applied in layers. The extrusion temperature (e.g. PEEK at 380-450°C), build platform temperature (120-200°C) and layer resolution (typically 100-300 µm) influence the component strength and dimensional accuracy (tolerances of ±0.2 mm or 0.5% of the dimension). PEEK components can achieve tensile strengths of up to 95 MPa and are flame-retardant according to DIN EN 60695-11-10.
  • Electron beam melting (EBM): Similar to SLM, but under vacuum and with electron beam as energy source. Particularly suitable for reactive metals such as titanium and nickel, which are processed at high temperatures.

The quality assurance of additively manufactured components requires a comprehensive testing strategy in accordance with DIN EN ISO/ASTM 52904 (qualification scheme for additive manufacturing), which includes non-destructive testing methods (e.g. computer tomography in accordance with ISO 17636-2, ultrasonic testing in accordance with DIN EN ISO 17640) and destructive tests (e.g. tensile test in accordance with DIN EN ISO 6892-1, hardness testing in accordance with DIN EN ISO 6507-1). The traceability of material batches and process data in accordance with DIN EN ISO 9001 is essential for safety-relevant applications and CE conformity.

3. Current development status: TRL and industrial implementation

Additive manufacturing for spare parts has made significant progress in the last five years and reaches a technology readiness level (TRL) of 7 to 8 in many application areas. This means that the technology has been validated in an industrial environment under realistic conditions and is about to be launched commercially or is already being used in initial pilot projects.

  • Key Player: Large mechanical engineering companies such as Siemens Energy, GE Additive and Liebherr are already using AM to produce complex gas turbine components, aviation components and hydraulic components. Medium-sized companies in the DACH region are increasingly exploring the potential for small series and spare parts.
  • Material qualification: The number of qualified materials for AM is constantly growing. There are now over 50 different alloys available for metals that meet the requirements of DIN EN ISO/ASTM 52911. High-performance polymers such as PEEK and PEI are available for plastics, which are resistant to chemicals and high temperatures (up to 260°C continuous operation) and are therefore suitable for demanding industrial applications.
  • Standardization and certification: The development of standards by organizations such as ISO/ASTM (e.g. DIN EN ISO/ASTM 52900 ff.) is progressing rapidly, which increases the acceptance and trustworthiness of the technology. TÜV Rheinland and other testing bodies already offer certification for AM processes and components, which ensures compliance with safety and quality requirements according to VDI 3405 Sheet 2.1.

Prototypes of additively manufactured spare parts range from simple plastic holders for wiring harnesses to complex metal components such as pump impellers or valve housings, which often enable functional integration and can therefore exceed the performance of the original. An example is the production of a complex valve block for hydraulic systems, where topology optimization and AM achieved a 30% weight reduction and functional integration, which reduced assembly time by 15%.

4. Potential impact on MRO: increasing efficiency and reducing costs

Additive manufacturing will fundamentally transform MRO practices in the coming years:

  • Inventory Reduction: With on-demand production capability, companies can dramatically reduce their physical spare parts inventories. This leads to a release of capital, lower storage costs (cost per cubic meter of storage space can be 50-150 EUR/year) and minimized obsolescence of parts. A reduction in inventory value of 20-30% is realistic, which can quickly save millions of euros for large systems.
  • Shorter delivery times: Instead of waiting weeks or months for critical replacement parts, they can be manufactured within days or even hours. This minimizes unplanned downtime and its associated production downtime costs, which, as mentioned above, can be significant. Reducing the Mean Time To Repair (MTTR) by 30-50% is achievable in many cases.
  • Improved component properties and functional integration: AM enables the production of components with optimized geometry (e.g. topology optimization), lower weight or integrated functions (e.g. cooling channels, sensors). This can lead to an increase in machine performance, a longer service life of spare parts and a reduction in energy consumption (e.g. 5-10% savings through optimized flow channels in pumps).
  • Individualization and small series production: For older machines whose spare parts are no longer available (end-of-life products), AM offers an economical solution for reproducing small quantities. This extends the service life of systems and avoids expensive new purchases. The costs for individual production using AM can be 50-70% lower than those for traditional tool production.
  • Digital supply chains: The establishment of digital spare parts warehouses (Digital Twin) enables global, decentralized production. A component can be transferred as a digital model from one location to another and manufactured there, reducing the dependence on complex global logistics networks.

5. Time frame and adaptation curve: Realistic milestones 2026-2035

The full integration of additive manufacturing into the MRO strategies of the DACH industry will take place gradually. Here is a realistic time frame:

  • 2026-2028: Pilot Projects and Materials Qualification (TRL 7-8): Companies begin implementing pilot projects for less critical spare parts made from polymers and select metals. The focus is on internal competence development, the qualification of materials and processes in accordance with DIN EN ISO 52900 and the establishment of smaller in-house production centers or collaboration with specialized service providers. The costs for an industrial SLM system are between EUR 300,000 and EUR 800,000, and between EUR 5,000 and EUR 150,000 for FDM systems.
  • 2029-2032: Advanced Integration and Scaling (TRL 8-9): Additive manufacturing will be used for a wider range of replacement parts, including more complex and critical metal components. Standardization is progressing and certification processes for AM components are established. Digital spare parts warehouses are being set up and integration into existing ERP systems (e.g. SAP) is becoming standard. Initial ROI analyzes show significant cost savings and increases in efficiency.
  • 2033-2035 and beyond: Full adoption and digital supply chains (TRL 9): Additive manufacturing will become an integral part of the MRO strategy. Global, decentralized on-demand production of spare parts is widespread. The technology enables completely new business models and maximization of system availability. The costs per component will continue to fall due to economies of scale and material innovations.

6. Challenges and barriers: technical, economic and regulatory aspects

Despite the promising potential, there are still significant challenges to overcome:

  • Material qualification and standardization: The diversity of materials and processes requires comprehensive qualification for each application, which can be time-consuming and cost-intensive. Although progress is being made (e.g. DIN EN ISO 52901 for terminology), detailed standards and norms are still missing for many specific industrial areas, especially with regard to the long-term durability of additively manufactured components under operating conditions (e.g. fatigue strength according to the FKM guideline).
  • Post-processing and surface quality: Many additively manufactured components require extensive post-processing (e.g. heat treatment according to DIN EN ISO 17663, mechanical processing, surface finishing) to achieve the required mechanical properties and surface quality (typically Ra 5-20 µm for SLM components, often up to Ra 0.8 µm required through polishing). This increases overall production time and costs.
  • Costs: The investment costs for professional AM systems are high, and the material costs for metals (e.g. stainless steel powder 80-150 EUR/kg, titanium powder 200-500 EUR/kg) are often higher than with conventional processes. A careful cost-benefit analysis is required to demonstrate ROI, particularly taking into account the savings from reduced downtime.
  • Data security and intellectual property (IP): The digital nature of spare parts raises questions of data security and intellectual property protection. According to VDE 0834-1, secure data transfer protocols and encryption are essential to protect design files from unauthorized access.
  • Skills shortage: There is a shortage of engineers and technicians with expertise in additive manufacturing, both in design and in system operation and quality assurance. Investments in training and further education in accordance with VDI 2244 are essential.

7. Recommendations for action for operations engineers: Strategic preparation

To maximize the benefits of additive manufacturing, operations engineers and MRO leaders should proactively consider the following steps:

  • Potential analysis and part screening: Identify spare parts suitable for additive manufacturing. Prioritize parts with long lead times, high obsolescence rates, high inventory value, or parts where functional optimization is possible. An A/B/C analysis of the spare parts is a proven tool for this.
  • Building skills: Invest in upskilling your engineering team in the areas of AM design, materials science and quality control. Cooperations with research institutes and specialized AM service providers can accelerate the transfer of knowledge.
  • Start pilot projects: Start implementing pilot projects for less critical components in order to gain experience and adapt internal processes. This creates trust in the technology and allows AM solutions to be validated in practice.
  • Develop digital infrastructure: Evaluate your digital infrastructure. Building a digital spare parts warehouse requires powerful data management systems and secure interfaces to production. Compatibility with existing CAD/CAM/CAE systems must be ensured according to VDI 2244.
  • Collaboration with experts: Work closely with suppliers like UNITEC-D. UNITEC-D, as a specialist for industrial spare parts, can play a central role in integrating additive manufacturing solutions into your MRO strategy through its expertise in material procurement, logistics and process optimization. We understand the specific requirements of the DACH manufacturing industry and can support you in selecting suitable technologies and materials.

8. Conclusion: A new era of MRO efficiency

The additive manufacturing of spare parts is not hype, but a technology that has the potential to permanently change MRO strategies in the industry. It promises significant improvements in asset availability, cost savings and supply chain flexibility. Although technical, economic and regulatory challenges remain, development is progressing rapidly. It is now crucial for CTOs and operations managers in the DACH manufacturing industry to recognize the potential of this technology early on and take proactive steps to integrate it into their MRO processes. Strategic collaboration with experienced partners is invaluable.

For more information and access to a comprehensive range of industrial components, visit the UNITEC-D E-Catalog.

9. References

  • DIN EN ISO/ASTM 52900:2022-03, Additive Manufacturing – Basics – Terminology. Beuth Verlag.
  • DIN EN ISO/ASTM 52907:2023-01, Additive manufacturing – qualification of processes – powder bed melting of metals. Beuth Verlag.
  • FKM guideline: Calculated proof of strength for machine components. Research booklets Research Board of Mechanical Engineering.
  • VDI 3405 Sheet 2.1:2018-05, Additive manufacturing processes – stereolithography – quality characteristics and testing of components. Beuth Verlag.
  • DIN EN ISO 9001:2015-11, Quality management systems – requirements. Beuth Verlag.
  • BMBF research report: “Future strategy for additive manufacturing – potential for Germany”, 2023.
  • Smith, J. et al.: “Economic viability of additive manufacturing in MRO supply chains”, Journal of Manufacturing Technology Management, 2024.