Connected metrology: Joining the dots and the value of being informed

Red pill or blue pill? That is the question. Is it better to actually know the exact dimensional characteristics and mechanical performance of engineered parts or to blithely assume that everything is fine unless and until it appears to the contrary? Dr Neil Calder, Owner of Engineered Capabilities Ltd, sets out his thoughts.

I think back to an early part of my engineering career, in a dark satanic Lancashire mill of a conventional machine shop producing metallic parts for Tornado aircraft, and I realise how fractured (and so often fractious) the information chains were. Metrology as a practice was somewhat localised and manufacturing variation was seen as a source of weakness and failure. Does this seem familiar?

Another early and formative experience was the experimental robotic assembly of fabricated assemblies, again for the Tornado aircraft programme. Flat and formed aluminium detail parts just didn’t fit together when presented for location and fastening by the high-accuracy robots of the day even though these had been passed the required upstream inspection standards. It was a very good example of being factually correct but still missing the point. Reliance on assembly jigs to force a geometric truth only hides the real nature of the detail parts which are in front of you.

Although some years old now, still one of the best industrial exemplars of connected and metrology-enabled digital manufacturing that I am aware of is the GKN Western Approach facility for A350 wing spar manufacture. Here, three large composite C-spars are brought together, their interfaces scanned, best fit determined automatically against critical dimensions, bespoke joining plates CNC machined and then mechanically fastened.

So, fast forward to 2025, when optical metrology is capable of achieving affordable measurement at the scale of the wavelength of light and information superhighways are capable of transferring libraries’ worth of data between manufacturing processes and supply chain participants. What are we going to do with all this rich and highly pertinent information? What critical decisions will be taken based on quantified individual part characteristics? The stand-alone nature of metrology facilities and actions on the shop floor are being challenged as the traditional binary go/no-go quality checks for engineering sector parts are becoming obsolete, to be replaced with a more genuine understanding of the critical characteristics of individual parts. In this respect, it’s appropriate to follow the decision thread and I can see a fundamental evolution from gateway to guidance.

This is particularly evident in developments involving aerostructure assemblies and is visible through the work of multiple High Value Manufacturing Catapult centres in the UK and in state-of-the-art manufacturing development facilities such as the University of Nottingham Omnifactory and BAE Systems’ Factory of the Future. In these, the actual and individual measurements from one stage of manufacturing influence the decisions of the next.

I hear Digital Product Passporting being talked about increasingly as a method for conveying information along manufacturing value chains, and in a range of different contexts. The simple, product provenance labelling version of this is aimed at consumers, but there is a pressing need to standardise and formalise the data in a meaningful sense for advanced manufacturing supply chains to allow the realisation of plug and play solutions. The value of metrology in manufacturing in the Industry 4.0 age is as much about the connected digital dimension through ICT as it is about making measurements in the first place.

I can sense a fundamental sea change in the philosophy of industrial metrology, from validating fit against the nominal standard dimensions of engineering drawing or 3D CAD model to one of understanding and dealing with variation. Like the surprise and disappointment of life when it fails to live up to expectations, it causes much less stress to embrace uncertainty in the first place and deal with it appropriately.