In the manufacturing industry, the importance of metrology, or the science of measurement, is often underestimated. However, inspection is critical for ensuring products work and operate safely.
Inspection ensures companies find and fix problems with a product before they reach the end-user, and the measurement and understanding of processes can be used to make those processes more efficient. However, inspection—even for conventionally manufactured products—is complicated. You must consider the accuracy, reliability, cost, speed and where in the process the measurement should reside.
This also varies across industries. In automotive, inspection of parts is normally in a batch test cycle to ensure there is uniformity. In aerospace, each part is inspected individually and there must be assurance that each part is identical.
As we enter the era of Industry 4.0, we are seeing a rise of additive manufacturing (AM), which brings even more complexity to inspection. Yet, it can’t be ignored since it’s integral to the future of smart factories and more efficient manufacturing processes. So, how can manufacturers prepare their inspection processes for AM?
With AM components, there are more variables than a machined part. Metrology needsto measure both dimension and material quality because these are essentially unknown before the part is manufactured. AM can also make intricate geometries and internal structures that may not be able to be inspected with a traditional coordinate measurement machine (CMM).
Additional inspection is required to identify whether there is physical defect in the properties of the AM component. This differs from subtractive manufacturing, in which much is already known about the properties of the workpiece, for example a steel or titanium billet, or a composite lay-up, before it is machined.
Achieving fast and reliable inspection of AM parts is the goal, but it’s much more difficult than traditional processes because the additive process is not as accurate as metalcutting. Manufacturers must therefore think of new, clever techniques to inspect AM parts—whether that part is an air-cabin partition or an automotive component.
There are currently no universal standards for how additively-made parts must be inspected, so defining a strategy can be difficult. However, we do expect the scale-up of AM to affect the standards industry, challenging international organizations such as ISO to set suitable standards for AM metrology in fast-paced, flexible factories.
Since there’s no current industry standard for AM, questions have been raised about if it really is necessary to define a tailored inspection process. The answer to that question is simple: it absolutely is necessary. If factories are to become faster and more flexible, inspection is a bottleneck to overcome, especially in industries where 100% inspection is required, such as aerospace. Measurement is, therefore, incredibly important for the advancement of smarter factories and working toward a true Industry 4.0 environment.
Manufacturers should aim to perfect a flexible inspection process for AM that can deal accurately with parts, while allowing them to be different every single time and in higher volume production.
Until AM inspection becomes standardized, manufacturers can couple lab-based CMMs with non-contact scanners, mobile and robot-mounted CMMs, as well as scanner arrays.
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