Conventional visual inspection requires opening inspection ports. This allows heat and hot gases to escape from the furnace, causes local cooling of the molten metal and gives operators only a brief glimpse of the current conditions. The assessment also depends on the experience of the individual operator.
The borescope enables continuous process monitoring. Images from inside the furnace can be displayed at a remote workstation, recorded and subsequently analysed. Operators can therefore monitor both the current molten metal level and how it changes throughout the production shift.
Effective cooling simplified the design
The main challenge was to protect the camera and optical components from high temperatures, radiant heat and contamination. The solution combines a water-cooled protective housing, protective glass elements and an air purge that reduces the build-up of contaminants on the front window.
Two versions of the cooling housing were developed: one with conformal cooling channels and another with a gyroid structure. Metal 3D printing made it possible to create complex internal geometries for heat removal directly within the housing. Thermal simulations and experimental testing supported the design process.
Effective cooling also allowed the camera to be positioned closer to the area being monitored. This eliminated the need for a long optical system with additional image-relay elements. The result is a more compact device with a simpler design that is easier to integrate into the furnace.
Validation at the BENEŠ a LÁT foundry
The version with conformal water cooling was deployed in production at BENEŠ a LÁT. At a furnace temperature of 745 °C, the temperature around the camera remained below 40 °C.
Subsequent operational testing captured an entire casting shift, including aluminium replenishment. Images taken at three-second intervals made it possible to track changes in the molten metal level and provided a dataset for automated image processing.
From images to level measurement
The development also includes software that identifies the molten metal surface in the image and determines its level. Following calibration for a specific furnace, it converts image data into a percentage fill level or the corresponding quantity of metal and displays changes over time.
The recorded images can therefore support continuous monitoring, retrospective assessment of the production process and documentation of exceptional events. Automated analysis provides additional information to support operators’ decisions.
The development was supported by the Technology Agency of the Czech Republic through the NCK MATCA project.
The borescope design can also be adapted for other high-temperature applications, such as glass or cement production. Suitability depends on the type of equipment, the conditions inside it and what needs to be monitored. Companies interested in using the borescope in their operations can contact us directly.
The NCK for MATCA is supported by the