The manufacturing of spare parts and classic components has been an integral part of our work at Seiffer & Steiner Präzisionsteile GmbH for more than 20 years. While conventional methods or manual reconstruction were often required in the past, today the entire process is fully digital and process-reliable.
In the classic car sector, we are regularly confronted with situations where original drawings no longer exist and components have not been produced for decades. In many cases, only a worn, damaged, or cracked sample part is available. Typical damage patterns include worn bearing seats, deteriorated sealing surfaces, cracks in housings, or fractures at structural weak points. Simply copying the part would reproduce the original weakness. Our approach therefore goes significantly further.
In the first step, the existing component is fully digitized using our T-Hawk Scan 2. Based on the generated point cloud, a precise and manufacturing-ready 3D model is created within the CAD system. During this process, wear conditions are reconstructed to their original state, dimensional deviations are corrected, functional surfaces are clearly defined, and tolerances are newly specified. The result is not a simple scan duplicate, but a technically sound design model.
Especially in classic vehicle components, it is often evident that certain housings or parts consistently failed at the same location due to inherent design characteristics. The causes are typically stress concentrations caused by sharp transitions, unfavorable wall thickness ratios, localized stress peaks at bearing or bolting points, or material fatigue associated with historical material grades. Through digital reconstruction, these critical areas can be specifically analyzed and structurally optimized. Possible measures include increasing radii to reduce notch stresses, adjusting wall thicknesses, reinforcing critical zones, or selecting modern, suitable materials. The objective is to maintain the original function and installation geometry while permanently eliminating known weaknesses.
Once the CAD model has been approved, manufacturing planning is carried out in Mastercam. Depending on geometry and technical requirements, 3-axis or 5-axis simultaneous machining strategies, adaptive roughing operations, and high-precision finishing processes are applied. Production takes place on our DMG MORI 5-axis machining centers. Particularly for complex housings, freeform surfaces, or internal functional contours, 5-axis technology offers decisive advantages in terms of accuracy, surface quality, and stable clamping concepts.
Finally, the manufactured components are dimensionally inspected on our Hexagon and Wenzel 3D coordinate measuring machines. Functional dimensions, fits, as well as form and position tolerances are fully verified. This ensures that the component not only matches the original geometry but also performs reliably in operation.
Modern spare part manufacturing in the classic sector is therefore far more than simple reproduction. Through the continuous digital process chain — from 3D scanning and CAD reconstruction to structural optimization, 5-axis machining, and final 3D inspection — components are produced that match the original in geometry and function, while often exceeding it in durability and load capacity.
We were able to present this expertise yesterday at Retro Classics Stuttgart directly to our target audience. The professional exchange with restorers, workshops, collectors, and technical decision-makers once again confirmed the strong demand for reproducible and structurally optimized solutions in the classic sector. The positive feedback and the highly specific technical discussions on site clearly demonstrate that digital process chains combined with in-depth machining expertise are key factors in the sustainable manufacturing of historical components.
