There is a key moment in any aeronautical project that is crucial to talk about from an engineering perspective: the aircraft tooling design stage. This entails the development of the tooling, jigs, fixtures and moulds that make it possible to manufacture large-scale airframe components without errors, ensuring they fit together with extremely tight tolerances.
This article offers an overview of aircraft tooling design from the point of view of our specialists, in which we apply our industrial experience to understanding the key challenges that are involved.
Aircraft tooling design is not just a technical discipline: it’s a combination of total precision, method, experience and a long-term vision. Here we’ll explain how Aritex overcomes the main challenges in aircraft tooling design and what opportunities are being created as this process evolves.
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What distinguishes aircraft tooling from other sectors?
Tooling is the element that enables a part to be assembled exactly as it was designed. The basic philosophy behind tooling is similar to the one used in the automotive sector: the starting point is a set of geometrical references, or datums, in which the part is positioned accordingly.
In aeronautics, this standard approach to positioning involves a radical shift in scale and responsibility. The large size and low individual rigidity of the components, combined with much tighter tolerances, mean that any deviation, no matter how slight, has a direct impact on the structural safety and aerodynamic performance of the aircraft. This means that tooling should be regarded as a way to ensure absolute geometric control rather than merely as a fixture for assembly.
The large size of aircraft parts imposes the need for maximum safety requirements and total precision. The purpose of tooling in the aeronautical industry is not therefore merely to keep the piece secure but to ensure that its geometry remains unchanged throughout the entire production process. This involves designing systems capable of monitoring deformations and displacements of the order of tenths of a millimetre in structures that are several metres in size, where any variation would compromise the overall result.
Another key feature of aircraft tooling design is the emphasis on automation. Automation in sectors such as the automotive industry is geared towards using large numbers of robots to achieve very short cycle times, but the priorities are very different in aeronautics. The focus there is on using automation to ensure ergonomic processes, process repeatability and safe handling of heavy loads, particularly in environments where mobile jigs or large components are used. This approach reflects the very nature of the sector: lower production volumes, greater operational complexity and extremely high standards of quality and precision.
Aritex’s 60+ years’ experience in industrial engineering means that our approach to aircraft tooling design meets the industry’s highest standards. For this reason, our starting point is not the tooling itself but the end result that the part needs to present once it is assembled.
This approach means that we define the tooling design after a thorough study of the tolerance chain. Thanks to this analysis we can anticipate how each benchmark, support and contact point influences the final geometry of the assembly, and design the tooling so that it acts as an active ally in meeting the geometric requirements specified by the customer, rather than as an additional source of variability.
Proper management of the tolerance chain is one of the key aspects of aircraft tooling, and one that requires a high level of technical expertise. That’s why we as strategic suppliers to OEMs in the aeronautical sector are constantly working with advanced technologies that ensure the highest standards of quality and reliability throughout the entire production process.
The big technical challenge: rigidity vs. deformation
One aspect that most surprises any first-time visitor to the world of aircraft tooling is the relation between the weights of the part and the tooling.
In practice, this requirement leads to weight ratios that may seem peculiar to an outsider, since tooling and fixtures weighing several tonnes are used to position relatively light parts. The reason is not the load, but the need to achieve levels of rigidity that minimise deformation under every process condition.
What matters most in aircraft tooling design (and why weight is not the main criterion)
The thinking behind tooling is not to design it just to bear a load, but rather to prevent deformations. A clear example of this is a wing: when it’s placed in the tooling and weight is added during the assembly process, any bending may change its position and put the entire aircraft design at risk.
The aim of the tooling design in this case is to ensure a deformation lower than two tenths of a millimetre. To make this happen, the tooling has to be extremely rigid.
The main criteria in aeronautics are rigidity and geometrical precision. In this context, design focuses not so much on structural strength, which is implicit when such levels of rigidity are achieved, as on the tooling’s ability to maintain a stable geometry under loads, additional weights and variable assembly conditions. This approach is one of the key factors that sets aircraft tooling apart from other industrial sectors.
Materials and technologies used in aircraft tooling
The choice of materials for aircraft tooling is not determined by cost or availability, but primarily by their structural performance, dimensional stability and compatibility with the work piece throughout the entire process. Each material is chosen according to how it helps to maintain the final geometry:
- Steel: the most commonly used material. Tough, economical, easy to manufacture and very stable for aircraft tooling design. Standard structural steels are used because they are so reliable.
- Aluminium: mainly used in areas of contact with the part, as it is a soft material that leaves no marks nor causes deformation.
- Special materials: carbon fibre or Invar, an alloy consisting mainly of iron and nickel, are used when there are major temperature changes in assembly plants or the tooling has to enter curing ovens. During the curing of composite parts, the thermal expansion of the part and the tooling must be closely matched. For this reason, in such cases, the tooling is manufactured using the same materials as the part itself.
Innovation and new opportunities
Although aircraft tooling has existed since the early days of the sector, new opportunities have emerged in recent years.
Additive manufacturing in aircraft tooling
Additive manufacturing opens up the way to designing optimised geometries that would be infeasible or inefficient with conventional processes. Its true value in aircraft tooling lies in combining design freedom with hybrid processes, where final precision is ensured through selective machining of critical surfaces.
We explored these hybrid solutions in projects such as MOLDAM, a collaborative project financed by EIT Manufacturing in which Aritex participated as an engineering solutions integrator: we manufactured tooling using additive methods with wider tolerances and then machined other surfaces.
This opens up the way to:
- Cost reductions
- Time savings
- Increased precision and greater freedom of design in tooling for small parts with a lot of curves or complexity
New optimised horizons with artificial intelligence
Generative AI is clearly a leading trend, and it is poised to play a transformative role in the aeronautical engineering industry. Although there are currently no tooling design projects that exclusively use this technology, there are expectations that advanced models may at some point be automatically designed from input data. The value of the engineering will then be in effectively defining the data, criteria and validations.
As was the case with the change from manual calculations to software, technology does not replace knowledge, it broadens it.
Collaboration with the customer and continuous improvement
Designing aircraft tooling is a collaborative effort and this is undoubtedly one of the major advantages of this process. The customer participates actively in the process from the outset, in key milestones such as the Preliminary Design Review (PDR) and the Critical Design Review (CDR).
Weekly online reviews enable tremendous improvements to be made in meeting customer expectations and early detection of deviations.
And the job isn’t over when the tooling is delivered. Regular recertification plans need to be defined, and Aritex makes sure that the geometrical references are maintained over time. Then we create maintenance plans that are integrated into the design, in order to resolve any incident as quickly as possible. These plans are not only a part of our contribution to aeronautics projects, they are an integral feature of any sector that Aritex is involved in.
When challenges and opportunities come together
One point that most concerns new aeronautics engineers is the extensive cycles of innovation, redesign and learning in the sector, which can be from 10 to 15 years. For example, one of the most challenging projects for Aritex was the production cell for the wing stringers in the Airbus A350, developed between 2008 and 2010. It was a challenge because there were no previous references in the sector at that time. Everything was uncharted territory.
The aim behind explaining this case is to highlight just how much we have learnt from this type of project: advanced simulation methods, complex assembly processes and a global vision that can then be transferred to other sectors. Despite being projects where the challenge was to create something from scratch, they also offered the opportunity to convert the solutions we created into benchmarks for the entire aeronautical sector.
So our advice to young engineers is clear: the capacity for constant learning is a definite competitive advantage for specialists in aircraft tooling.
Aritex and the future of aircraft tooling
One can see therefore that Aritex operates as a strategic provider for major manufacturers like Airbus. Our role is not only to complete projects out, but also about partnering evolution in the sector, providing engineering, innovation and reliability where mistakes are not an option.
Designing aircraft tooling will continue to be one of the invisible but essential elements in the sector. Actually, the future of aeronautics lies at the crossroad of precision, technology, and human ingenuity.
In an industry where there is no margin for error, real value lies not just in the tooling itself, but in the ability to view it as part of the entire production system.
