Full-Surface Infrared Temperature Monitoring in Float Glass Production

Solution

The use of line-scanning infrared imaging enables continuous, full-surface temperature mapping during the cooling phase. This allows operators to monitor and adjust process parameters in real time, ensuring consistent glass quality and stable production performance even in demanding environments with high temperatures and airborne particles.

The Risks of Uneven Temperature Distribution

The float glass process produces large sheets of perfectly flat glass by floating molten glass on a bath of molten tin, resulting in a smooth, uniform surface. After leaving the tin bath at approximately 265°C, the glass moves through controlled cooling zones, gradually cooling to about 55°C.
This gradual cooling is essential to prevent thermal stress, which can lead to visible defects, microcracks, or spontaneous breakage during later processing.

A major difficulty in this process lies in maintaining a uniform temperature profile across the entire sheet. Traditional point pyrometers only measure at fixed locations, providing limited insight into surface temperature variation. As a result, uneven cooling patterns can go undetected, compromising product quality.

Additionally, high temperatures and dust within the cooling section can interfere with conventional sensors. Dust accumulation on optics or thermocouples reduces measurement accuracy and system reliability over time.
For this reason, a real-time, full-field infrared temperature measurement system is essential — both for process stability and for improving product yield.

Line-Scanning Infrared Imaging for Complete Surface Mapping

Integrating Optris PI 400 infrared cameras into the float glass cooling line provides a precise, non-contact solution to these challenges.
The compact PI 400 (46 × 56 × 68 mm) delivers high optical resolution (382 × 288 pixels), enabling detailed thermal imaging across the full glass width during cooling.
Operating in the 8–14 µm spectral range, the camera is optimized for glass temperature measurement and can monitor temperatures from –20°C to 1500°C, covering all stages of the cooling process.

As the glass sheet moves through the cooling zones, the PI 400 continuously captures line-by-line thermal data. The line-scanning function merges these profiles into a complete temperature map, allowing operators to visualize the entire surface in real time.
This makes it possible to detect and correct localized hotspots immediately, preventing internal stresses and ensuring consistent cooling.

The camera’s frame rate of 80 Hz ensures fast, accurate measurement even in high-speed production environments. Interchangeable lenses with fields of view up to 80° allow flexible adaptation to various installation conditions and glass widths.

Rugged Design for Harsh Environments

To guarantee long-term reliability, the PI 400 is installed in a protective cooling housing that allows operation in ambient temperatures up to 250°C.
Integrated water-cooling and air-purge systems maintain stable operating conditions, while a laminar air purge device keeps the lens free from dust and debris — crucial for consistent optical performance.
Connectivity options such as Ethernet and GigE ensure seamless integration into existing process control systems.

Automated Process Control for Efficiency and Cost Reduction

Implementing Optris PI 400 cameras in float glass production allows manufacturers to automate the cooling process.
By feeding real-time temperature data directly to the plant’s control system, the camera enables closed-loop regulation of cooling parameters. If temperature deviations occur, the system automatically adjusts airflow or cooling intensity to restore balance.
This capability improves quality consistency, reduces waste, and lowers energy consumption by avoiding unnecessary overcooling.

With Power over Ethernet (PoE), USB-to-GigE connectivity, and PIX Connect software, multiple cameras can be networked and monitored simultaneously across different cooling zones.
PIX Connect provides advanced features such as temperature profiling, zone alarms, and data archiving, making it a powerful tool for process optimization and quality assurance.

Summary

The Optris PI 400 infrared camera provides precise, continuous temperature monitoring across the entire glass surface, even in harsh production environments.
Its combination of high-resolution imaging, robust protection, and real-time integration enables float glass manufacturers to enhance quality, increase yield, and reduce operating costs — setting a new standard for process control in modern glass production.