The story of every tunnel begins well before excavation — in the precast department. It is there, inside steel moulds, that concrete takes shape, becoming the segments that will line the tunnels of the future.
For AB Tunnelling, steel moulds are not just tools, but the very heart of the precast process — where precision engineering transforms steel and concrete into durable and safe infrastructure.
AB Tunnelling collaborates in the segment precast sector with the high-profile international company Korea Mould, creating steel moulds that combine advanced design, mechanical precision, and durability to support extremely complex tunnelling projects.
1. What are segment moulds?
Precast segment moulds are metal structures designed to shape and contain concrete during the production of tunnel lining segments. They represent the link between design and construction reality, defining the geometry, finish, and performance of each individual precast element.
Each mould must guarantee:
- Rigidity under vibration and concrete pressure;
- Ease of opening and demoulding;
- Extremely tight dimensional tolerances;
- Perfect integration with accessories and gaskets.
Unlike traditional formwork, steel segment moulds are designed for repeatability, precision, and durability — capable of withstanding hundreds of production cycles without deformation.
2. Experience and engineering expertise
The experience of AB Tunnelling and Korea Mould goes beyond production: it starts with understanding the client’s design requirements and extends throughout the entire production chain.
Each mould begins with the design of the segments — geometry, curvature radius, segment type (key, counterkey, pier), and mechanical connections. From this data, our technicians develop a complete 3D model of the mould system, optimizing stability, ergonomics, and ease of maintenance.
Our expertise includes:
- FEM structural analysis for stiffness and mechanical behavior;
- Positioning of pneumatic or electric vibrators for uniform compaction;
- Integration of embedded inserts (dowel sockets, grout and lifting and service sockets, anchored gaskets);
- Design of complementary equipment (vacuum lifting device, tilting table, mechanical clamps);
- Engineering of carousel systems for automated production, where required.
Experience helps prevent deformation, reduce cycle times, and ensure consistent quality.
3. Quality and production process
Quality starts with the raw materials. Each steel mould is made from certified high-strength steel, cut and machined using laser and plasma technologies to achieve clean edges and perfect dimensions.
The production phases include:
- laser cutting and preparation of plates and profiles;
- controlled welding to prevent deformation;
- CNC machining with precision up to a tenth of a millimeter;
- pre-assembly and alignment checks;
- 3D inspection with a laser tracker.
Each component is protected, painted, and tested before shipping. The result is a mould that maintains dimensional accuracy and mechanical integrity throughout its service life.
4. Precision: where microns count
In the precasting process, precision is crucial. Even minimal deviations can compromise the assembly of tunnel rings. For this reason, AB Tunnelling uses a digital metrology control system based on:
– 3D laser scanners and high-precision micrometers;
– tolerance checks at every production stage;
– data recording to ensure full traceability.
Precision is not an outcome but a design principle: each mould is built like a measuring instrument.
5. Anatomy of a steel mould
A complete mould includes:
- a rigid base ensuring stability and flatness;
- movable side shutters defining the segment shape;
- head shutters shaping the radial joint;
- vibration systems for concrete compaction;
- fixing pins and clipping groove for accessories and gaskets.
Particular attention is paid to gaskets, with dedicated clipping groove that preserve their shape and functionality during casting and demoulding.
6. Robustness, reliability, and intelligent kinematics
Durability is a requirement, but efficiency defines its value. Our steel moulds incorporate linear translation kinematics, which reduce stress on the sealing gaskets and improve surface quality.
Components such as guides, pins, and locks are designed to withstand repeated loads, while hydraulic or mechanical assistance makes operations faster and safer.
Every mechanical detail is the result of years of experience to ensure robustness, ergonomics, and operational safety.
7. Maintenance and long-term value
A steel mould for precast segments is a long-term investment. Proper maintenance preserves its precision and durability.
AB Tunnelling provides dedicated instructions and training, promoting:
- periodic inspections of moving parts;
- regular lubrication and cleaning;
- use of vegetable-based waxes and release agents that respect both the environment and the health of operators.
With proper management, a steel mould can maintain its performance for hundreds of casting cycles.
8. Innovation and automation in precasting
The precasting process is constantly evolving. AB Tunnelling, in collaboration with Korea Mould, is developing a strategy to integrate automation, robotics, and digital measurement systems into next-generation mould design — with the belief that the synergy between craftsmanship and technology is the key to achieving ever-higher levels of productivity, safety, and precision.
9. Sustainability and safety
Modern design must combine efficiency and responsibility. This is why AB Tunnelling and Korea Mould adopt sustainable practices such as:
- low environmental impact release agents;
- energy-saving cutting and welding systems;
- ergonomic and operator-safe designs.
sustainability is an integral part of our philosophy: precision and environmental respect can coexist.
10. The AB Tunnelling value
AB Tunnelling is more than a supplier: it is a technical partner. A multidisciplinary team oversees each project from design to commissioning, offering:
– dimensional accuracy and reliability;
– high productivity;
– ease of maintenance;
– integration into existing systems.
Each steel mould illustrates our mission: transforming precision into performance.
11. Conclusion
Every segment begins with a steel mould, and every mould is the starting point of a tunnel’s quality. Inside those steel structures, concrete becomes form, strength, and the future.
For AB Tunnelling, steel moulds represent the heart of precasting — the place where experience, innovation, and reliability meet.
🔗 Learn more about AB Tunnelling’s tunnel segment moulds — engineered for precision, durability, and efficiency.
🧩 Need a custom precasting solution? Contact our engineering team to design steel moulds tailored to your tunnelling project. 📩 Contact us
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