WCA September 2022

Technical Article

Traceability – why is it important? By Kjell E Johnsen, Conoptica AS

This article looks at the very foundation of measurement technology. We explain the concept of traceability and why this is so important, not only for our measurement systems but for everyone, in all aspects of life. One of the most important features of the Conoptica measurement systems is that they provide measurements with traceable accuracy. In this seemingly innocent sentence, I am referencing two concepts that are crucial to our business: traceability and accuracy. In this article I will focus on the traceability. The author of the article, Kjell E Johnsen, started at Conoptica as a service engineer and is currently the sales andmarketing manager for wire and cable products. His background is in technical and sales positions in various high-tech companies. He holds an MSc in structural engineering and an MBA in strategy and innovation. For 25 years Conoptica has supplied the wire industry with drawing die measurement systems. Its focus has always been on the measurement technology and the importance of accurate, consistent and traceable measurements.

CE and accuracy class markings on the Swedish-brand tape measure

Most of us think this is trivial. One millimetre on my tape measure should be the same as one millimetre on your tape measure; one gram on my scales vs one gram on yours and so on. If we take a closer look, we see that this is not necessarily the case at all. I have two tape measures at home. One is an expensive one from a well-known Swedish brand. The other is a cheap no-brand one. The difference is €20 and almost 5mm on one metre. (Yes, the no brand one has markings showing almost 5mm less.) Which one do I trust for measurements? The expensive Swedish one, of course. Why? Because on this tape measure there is a reference to a European Standard class rating, telling me the accuracy. On the other there is nothing, except themanufacturing country. Why is this a big deal? Well, it’s obvious isn’t it? If you order some part from me that is supposed to fit into another part you have, you will tell me the dimension requirements when you order. Now, if you used a no-brand tape measure (like the one I have) to find those dimensions, while I use the Swedish tape measure when I manufacture the part for you, my part will not fit into your part. You will complain, of course; I will tell you that you are wrong, and then the circus will start. You don’t get your part and I end up with a dissatisfied customer. First of all, who is right? Without the existence of an agreed upon definition, the concept of measuring loses its meaning. For something measured with a tape measure, it is fortunately easy. An international standard exists for lengths and units, and one metre is well defined. From Wikipedia: “The metre is currently defined as the length of the path travelled by light in a vacuum in 1/299,792,458 of a second.” This is the definition. It is not so practical in everyday life. Most countries have an institute of standards to handle the matters of

The basic idea of any measure ment system is that it should tell you the relevant dimensions of the object you are measuring – a tape measure for measuring the length of objects, a scale for measuring weight and so on. Equally central is the idea that the measurement you get shall have a reference – that is what we have units for: metre for the tape measure and grams for the scales (or inches and pounds if that is your persuasion). The only reason for measuring something is that we want to compare it with something else. Therefore, my scales should show the same weight for any given object as your scales. If this were not the case, we would see many interesting results, for example in the world of cooking and baking.

Conoptica’s CU6S drawing die measurement system

54

www.read-wca.com

September 2022