This is achieved through controlled heating and cooling processes or by relieving mechanical stress in foundry parts through annealing at specific temperatures and durations.
Depending on the heat treatment process, it can occur in annealing furnaces or involve surface hardening techniques using induction, flame, or laser heating followed by rapid cooling.
For example, in surface hardening processes, the surface layer of a steel part is partially inductively heated, and then its temperature is rapidly
lowered using a cooling emulsion-water mixture to bring it below a certain limit. To achieve the desired surface hardness, both the heating and cooling temperatures are measured and controlled to ensure an effective heat treatment process.
Another common heat treatment process involves dipping heated parts from a furnace into a cooling basin to cool them entirely. Monitoring the part temperature before and after cooling is crucial to ensure the quality of the process and the resulting parts.
THERMOCOUPLES
In many applications, portable thermocouples are still used to measure part temperatures after cooling. However, with larger parts of varying sizes and different materials, the temperatures across their surfaces can differ due to internal heat conduction. This can lead to missed areas with hotter or cooler temperatures, as these spots are typically not visible to the operator. Additionally, the repeatability of portable thermocouple measurements is limited.
THE SOLUTION | USING STATIONARY THERMAL IMAGERS IN HEAT TREATMENT PROCESSES
The primary difference between point temperature measurements, such as those taken by contact thermocouples or non-contact pyrometers, and thermal imaging measurements is that thermal imagers provide a fully radiometric calibrated image across the entire field of view, offering precise temperature measurements at each camera pixel. For instance, the AMETEK Land LWIR-640 thermal imager provides over 300,000 pixels and temperature points in a single image.
Thermal images and videos offer a comprehensive view of the temperature distribution, including hot and cool spots and temperature profiles at specific moments or over time (during cooling down). In certain applications, when parts emerge from the cooling basin, their remaining internal energy may heat up the surface, as depicted in the time/trend graph above.
The LWIR-640 thermal imager can be installed in an industrial cooling and purging enclosure, ensuring reliable performance in harsh industrial environmental conditions. It can operate autonomously using the internal webserver for configuration and integrated I/O options for connecting and communicating with the plant and process control system. The internal alarms can be utilized to indicate threshold temperature levels or continuously monitor the part temperature on a site display.
For further monitoring, analysis, and data capture, up to 16 imagers can be connected to the IMAGEPro thermal imaging and process control software, enabling direct communication with the plant control system. This includes capturing temperature data and images for each part being heat treated, ensuring quality control and documentation.
Industrial thermal imagers are available in different sub-ranges and spectral responses, catering to various applications and temperature ranges from -20°C to 2000°C.
CONCLUSION
Industrial thermal imaging provides a holistic view of parts' thermal conditions in real-time, allowing reliable detection of cold and hot spots and tracking temperature deviations over time. The integration of this technology is facilitated by analog and digital interfacing for autonomous operation or through advanced thermal imaging software, enabling comprehensive data capture and on-site or remote monitoring.
AMETEK Land's family of industrial thermal imagers and systems includes stationary thermal imagers, furnace thermal imagers, and a wide range of industrial accessories. By leveraging thermal imaging technology, you can feel the heat and measure it reliably! For more information, contact our global sales offices, applications, and service engineers to discuss your specific application and find the most suitable measurement solution, optimizing costs and enhancing process safety and efficiency.