Discovering the metrology
Metrology: precision driving quality and performance at Mora Group
Metrology plays a key role in the quality assurance of industrial parts, from moulds to complex thermoformed parts. A veritable science of measurement, it guarantees compliance with the most stringent requirements. It is therefore an essential link in securing every stage from development to series production. Vincent Collard tells us more about metrology in MORA Group’s processes.
Bonjour Vincent, Pourriez-vous nous décrire votre parcours professionnel ?
I’m Vincent Collard, Technical Director of the MORA Group and a mechanical engineer with a degree from UTC Compiègne.
After starting my career in subcontracting, I spent 15 years in the automotive industry, where I developed engine sensors and mechatronic systems for major manufacturers such as PSA, Renault, BMW and Ford.
There I managed teams and supervised the entire project lifecycle, from design to production.
I then took on new challenges as a key account project manager in the solar power plant sector, managing major projects for EDF and Aéroports de Paris.
Today, thanks to this experience in managing complex projects, I’m able to support MORA’s clients with rigour and expertise.
Can you explain what metrology is?
Metrology is the art of accurately measuring the parts we manufacture, in order to validate their conformity with the customer’s drawing. It is based mainly on the dimensional criteria defined in the drawing: lengths, diameters, thicknesses, locations, etc. and above all the associated tolerances.
We have several stages in our metrology process.
The first stage is exhaustive metrology. This involves measuring all the dimensions in the drawing on the first parts to come out of the mould. This stage is often carried out by specialist external laboratories.
After this phase, we make any necessary adjustments. At the end of the development process, we again carry out a full metrology test to definitively validate that the part conforms to the design.
However, what is very important to understand is that not all dimensions have the same level of importance. Some dimensions are considered critical or significant. These are marked on the plan with specific identifiers. These critical dimensions are generally taken from the customer’s product FMEA. These are dimensions which, if not respected, could lead to malfunctions, safety problems or regulatory non-compliance.
These critical ratings therefore receive special attention. Generally speaking, they are dealt with in two ways, often combined. Firstly, we carry out capability studies during development to assess whether the dimension is well under control in relation to the tolerances imposed. We then monitor production to ensure that the dimension remains compliant throughout the manufacturing process.
In practical terms, during development and whenever the product changes, such as after a mould rework, we carry out capability studies to check that the dimension is correctly centred and that it is capable, i.e. compliant and stable. This work continues right through to the final phase, when the initial sample report (PPAP in the automotive sector, or QO in the medical sector) is submitted.
In series production, the monitoring of critical dimensions is very often required. It may be carried out at the start and end of each batch or sometimes every 8 hours, depending on the customer’s requirements.
What specific process or organisation have you put in place at MORA GROUP for this expertise?
At Mora, we have set up a specific organisation to manage all this seamlessly. We identify critical dimensions at an early stage in the development process and monitor the continuity of measurements between development and production, to avoid any measurement discrepancies or biases.
We pay particular attention not only to the measurement of parts, but also to the quality of the measuring equipment itself. The equipment must be suitable and accurate, and the results must be repeatable and reproducible – in other words, reliable, whatever the operator.
To achieve this, we systematically carry out R&R (Repeatability and Reproducibility) studies on the measuring equipment used for these critical dimensions. In some cases, our customers also carry out their own checks upon receipt.
There are two possible situations:
Correlation of measurements: we compare our results with theirs, looking for any bias. Ideally, this would involve using the same equipment and the same fixtures. We sometimes suggest developing duplicate set-ups to limit differences, but this isn’t always feasible because our customers don’t always have the same machines as we do.
Full delegation of measurement: some customers prefer to delegate measurement to us and validate our metrology reports, capability studies and certificates. In this case, Mora is responsible for batch release.
Another important point is that some parts are particularly complex to measure, for example when they are massive or have significant material shrinkage. This makes metrology even more complicated, as achieving tolerances of ±0.02 mm on such parts requires very high levels of precision. At Mora, we have experience of this type of part, and our procedures guarantee rigorous monitoring and reliable measurements.
How does expertise in metrology represent an asset for Mora?
It’s not just the fact of doing metrology that’s an asset. It’s the internal organisation dedicated to dealing with it that makes all the difference at Mora Group.
When I took over as Technical Director in 2016, quality was not under my authority. This could have led to some cumbersome exchanges.
At the time, the Quality department provided the measurement reports, without being involved in the decision whether or not to rework the moulds. This meant longer lead times and a lack of efficiency in the event of a challenge from the Technical Department and the need for further analysis.
In 2019, I integrated development quality directly into my team. Since then, measurements, analyses and decisions have been taken smoothly and quickly.
Quality, project managers and tooling experts work together on a daily basis. As soon as there’s a question about a measurement, we talk directly to each other, arbitrate on the same day and make rapid adjustments. This enables us to speed up fine-tuning, prioritise actions more effectively and avoid silos between departments.
This integrated approach is a real differentiator compared with other companies. I see it every time I present our organisation to customers. They immediately see the benefit and often remark on it. In their own structures, they often still have a strict separation between quality and technical, which slows them down.
We have also integrated tool purchasing into the department. This allows us to control internally all decisions relating to additional costs or technical choices for moulds, while always remaining consistent with the project challenges.
