Joining solutions moving fast

Jonathan Craven, operations director at Alcoa Fastening Systems & Rings

Joining materials in safety critical applications should not be underestimated. A fastener that costs a tiny fraction of the total bill of materials could have catastrophic, and expensive consequences if it should fail. It is vital to the integrity of a product.

Materials technology has always been ahead of the joining technology available. It is as inescapable as it is inevitable, and it means that fastener technology is constantly being forced forward.

There are plenty of standard fastening components available from catalogues for standard applications, but these are not core market that currently are showing such potential in Europe and also happen to be the markets served by Alcoa Fastening Systems & Rings (AFSR). Our position is that if two materials can be joined by a standard nut and bolt, then use a standard nut and bolt. However, if the requirement is for hostile and demanding applications, with varied and new materials, and using multi functional fastening solutions, then more expertise is required. This is the end of the market that is most innovative, demanding and exciting. Usually they include applications where risk is attached – or at least reliability is non-negotiable.

Aerospace, rail, and renewable energy all come into this category. And automotive, with its drive towards lightweighting and alternative materials is at the forefront. Fastening together sheets of steel is straightforward until it becomes sufficiently thin (under 2mm) that the fastener, or the fastening process, could adversely affect the performance of the material. The same is true of composites. Inappropriate fastening can result in hoop stress being formed round the fastener, which can generate crack propagation and other damage to the materials.

As we move forward the trend for lighter vehicles will only increase and so too will the fastening problems associated with it. The same is true of other applications – a wind turbine manufacturer reported that a previous fastening solution solved one problem but created five more. The trouble is that fastening expertise has suffered in the UK after three decades of decline in engineering and the pool of engineers with real problem solving ability is a small one.

However, that pool is not empty for engineers who are trying to stretch the technology envelope; engineers who are looking to come up with products that will change the landscape of their sector. Such engineers need their suppliers to provide technology that is both cutting edge and proven – a curious contradiction. AFSR can provide both the technology and the expertise to deploy it appropriately. Increasingly as the UK establishes its niche in high-end engineering, engineers will look to their suppliers to develop enabling technologies.

ASFR is uniquely positioned to do this with its team of engineers in the UK and a technology centre in Pittsburgh, USA which provides global customer support. At a time when materials development is moving so quickly, fasteners must be able to do their job without damaging these materials. And there is no point of having high quality fasteners and high quality materials if the former is going to damage the latter. Compatibility is all important.

Other trends are emerging. We are being faced with more ‘aggressive’ wish lists from industry, particularly with regards to product predictability (inside the joint) and also installation accountability. PPAP (Production Part Approval Process) is an example of the first of these, used in the automotive industry, where the customer is given a full breakdown for each part – not just its dimensions but how and where it is made, what materials are used and where do they come from. It essentially becomes a contract with the customer that we suppliers can be audited against. Having started in automotive this methodology is now being adopted in many other sectors.

Installation accountability is on the same lines. It has emerged in such areas as high end transportation where they are looking for more information about the installation method. ASFR provides a hydraulic installation system that also includes identification of the operator, the tool, the batch of fasteners, and a forced displacement curve for the installation. Therefore, should a rail company be audited by one of the national rail boards, they can provide certificated evidence to say that fastener was installed by a qualified person on particular day from a certain batch. It is an echo of the requirements of the aerospace industry, where traceability is a huge issue.

Installation is in itself another issue that can be overlooked – engineers tend not to think about design for manufacture when it comes to fasteners. But, particularly in the application areas discussed here, fasteners must not be viewed as a component, rather that fastening must be seen as a system. The majority of fasteners require a dedicated machine to install them. The capital cost of this machine must be taken into account when specifying the fastener, but also in the actual design the machine needs to be able to access the site of the fastener.

This ties in with the over-riding trend with these demanding, safety critical applications – the engineers are looking for solutions. If that requires a bespoke fastener or installation system, Alcoa has the set-up, the manufacturing and engineering knowledge to provide them.

It means the functional performance of the products can be designed in at a metallurgical level, shaped by the manufacturing methods, special heat treatment processes and special grades of material.

If I was to look back from the year 2020, for all of the advances we are seeing in fastener technology, I think the most remarkable shift will be in productivity. Whether it is with us suppliers and our turnaround times, with the design to prototype cycle or most particularly with the product manufacture itself, which will of course include more automation of fastener installation. Closer collaboration in this case between supplier, designer and manufacturer is clearly the key to its success.