High temperature quality inspection

Metrology-grade direct scanning brings quality inspection to extreme-temperature applications | Hexagon’s direct scanning laser trackers

With metrology-grade direct scanning at a distance, Hexagon’s direct scanning laser trackers – the Leica Absolute Tracker ATS600 and ATS800 – are delivering time and raw material savings in new areas of production. The ATS600 is optimised for fast measurement of large surfaces, while the ATS800 provides higher-accuracy direct scanning for applications with more demanding dimensional requirements.

As measurement technologies develop and improve, quality inspection is gradually making its way into increasingly challenging areas of production. Some of the applications in which manufacturers are currently trying to improve efficiency through the introduction of metrology-grade measurement tools involve extreme temperatures beyond the range of conventional measurement equipment, for instance in the case of inspecting recently forged parts.

Forging large components

When it comes to the forging of large components, there are sound reasons for investing in a measurement technology that can ensure the forged part is as close as possible to the desired dimensions of the final workpiece. On the one hand, an oversized forging can result in a significant waste of time and material. This is because excessive machining is required to bring the raw forged part within design tolerance. On the other hand, an undersized forged part is an even greater problem. The entire piece may need to be scrapped if it’s not large enough in any single dimension to accommodate the design of the final part. This of course results in an even greater loss of time and material.

Dimensional inspection is the natural answer to this challenge, but this is a difficult process when extreme temperatures are involved – the typical tools of metrology are simply not capable of withstanding temperatures of up to 1000°C, as seen in the forging of large metal parts.

Hexagon’s direct scanning laser trackers, the Leica Absolute Tracker ATS600 and ATS800, offer a solution to this problem through their ability to measure surfaces directly from a safe distance, without the need for a reflector on the hot component. 

The two systems provide different strengths. The ATS600 is the faster option for scanning large surfaces and rapidly capturing the overall geometry of large components, while the ATS800 provides higher-accuracy direct scanning for applications requiring tighter dimensional information or more demanding inspection results. 

Direct scanning technology

Direct scanning is a defining capability of Hexagon’s direct scanning laser trackers. Unlike conventional laser trackers, the ATS600 and ATS800 can measure points directly on a surface without requiring a reflector. The technology allows users to target specific measurement areas through selective scanning, rather than collecting data across a wide area that must subsequently be filtered.

The ATS600 and ATS800 can also deliver immediate results thanks to their integration with standard metrology software processes, allowing for the direct comparison of actual to nominal dimensional values.

Within this shared direct scanning concept, the two trackers address different measurement priorities: the ATS600 delivers faster coverage of large surfaces, while the ATS800 delivers higher-accuracy direct scanning and better performance with higher angles of incidence for more demanding dimensional inspection tasks.

High-temperature kiln alignment

Forging isn’t the only application in which high temperatures cause problems in performing accurate measurements. In the cement industry, kiln alignment is a crucial regular task. Cement kiln misalignment can cause excessive forces that lead to wear on components such as gears, bearings, riding rings and rollers. This can lead to extremely expensive kiln failures well before the expected lifetime of the kiln is reached.

Even before failure, kiln misalignment can result in an inefficient process that costs more time and resources than needed. The kiln stage is the main energy-consuming and greenhouse-gas-producing step in the process of cement manufacture, so any efficiency improvements are highly coveted in the industry.

Alignment is therefore essential, but it is not straightforward. This is due to the high temperatures reached during the pyroprocessing stage in the manufacture of hydraulic cement – at certain points in the process the kiln will reach temperatures of up to 1450°C.

Again, Hexagon’s direct scanning laser trackers provide a solution through their ability to measure selected areas accurately from a safe distance. When the kiln is heated, it is certainly not possible to place reflectors or targets across the cylinder to verify and correct the alignment.

For rapid measurement of larger kiln surfaces, the ATS600 offers the advantage of higher scanning speed, allowing large areas to be captured efficiently.

Selective scanning and integrated imaging allow a single operator to measure only the areas of the kiln needed to define the alignment, enabling regular alignment checks that help ensure high efficiency and reduce unnecessary wear.

Since the launch of the ATS600 in 2019, new applications for direct scanning have been identified regularly across a wide range of industries. The ATS800 expands Hexagon’s direct scanning laser tracker portfolio with higher-accuracy direct scanning, giving manufacturers a choice between faster large-surface measurement with the ATS600 and higher-accuracy inspection with the ATS800. 

As quality and production engineers become more familiar with Hexagon’s direct scanning laser trackers, there can be no doubt that many more interesting applications will continue to be discovered.