Accurate & Precise Temperature Measurement for Glass Industry

Dpstar provides a wide range of infrared products for the glass manufacturing industry. These include noncontact infrared line scanners, smart sensors, and modular systems (sensors and monitor units), all easily customized to fit your glass manufacturing applications. Our non-contact temperature monitoring and thermal profiling solutions are customized for the most unique applications and are designed to perform in the most demanding environments. We provide our customers with tools that allow for a fully automated process so production can continue around the clock while they get the temperature data needed to help ensure product quality, process control, on-site safety and more. 

Our infrared sensors are used with furnaces, bulk glass, Melter, regenerator, refiner, forehearth, gob, molds, float lines, and annealing lehrs, as well as at the cooling and coating areas. Efficient temperature measurement shows all aspects of the heating or cooling processes, such as whether a regenerator is too cool or too hot, or whether the tin bath and lehr zones are at their correct temperatures. Careful monitoring, from the molten state through the cooling process, ensures that the glass retains the desired properties as it travels through the manufacturing process. Our infrared sensors take temperature measurement one step further. A wide range of optics, including the remote controlled, motorized, variable focus in the Marathon MM, covers an enormous variety of applications. The sensor can be aligned with the target by using the integrated through-the-lens sighting, plus either laser or video sighting for correct target location. Simultaneous analog and/ or digital output allows temperature data to be integrated into a closed loop control system for remote temperature monitoring and analysis. 

Major Applications 

Melt Furnace 

Melters can be either cross-fired (as shown in Figure 1) or end-fired. Regenerators improve fuel efficiency by heating incoming air and alternating the firing direction. The temperature of the brick packing in the regenerator columns increases as the heated air from the furnace escapes. When this packing reaches the appropriate temperature, the cycle is reversed and these columns are then used to heat air entering the furnace. To ensure maximum operating efficiency, Raytek sensors are mounted at the top and bottom of each regenerator to trigger the air flow and firing direction at the optimum time. Using Raytek sensors to monitor the packing and refractory material for deterioration is crucial in planning the maintenance and rebuilding schedules, and eliminating emergency situations which could cause a costly, unscheduled shut down. The temperatures at the port arch and the bridgewall are measured to maximize the useful life of the refractory material. The precise aiming capability of Raytek sensors allows measurement of individual target bricks and avoidance of the furnace flame. 

Flat Glass  

Temperature monitoring is critical in each stage of flat glass production (Figure 2). Incorrect temperatures or rapid temperature changes cause uneven expansion and contraction, resulting in improper annealing. At the tin bath, sensors are mounted over each zone to insure correct glass temperature. The annealing lehr also has several temperature control zones. Sensors with air-cooled ThermoJacket housings are mounted at each zone to measure flat glass surface temperature and to monitor edge-to-edge temperature distribution. For this reason, ES150 systems are mounted between the tin bath and lehr, at specific zones in the lehr and at the exit, to scan across the width of the glass. Areas with surface imperfections, such as a crack, a bubble or a thinner or thicker section will cool differently than the surrounding glass and are visible as a realtime color image on the computer screen.  

Bottles and Containers   

From the furnace, the molten glass flows into one or more forehearths (depending on the size of the operation), where the molten glass is kept at a uniform temperature. At the end of the fore-hearth, the gob is dropped into molds where initial forming is done by either a blowing process (compressed air) or pressing process using plungers and molds (Figure 3). Maintaining the proper temperature in the forehearth is critical to ensure that the molten glass is in the proper homogenous condition when it reaches the exit. When the gob is forced out of the opening, it must have the proper viscosity (a 1°C change causes a 1% change in viscosity). Infrared fiber optic sensors are placed along the forehearth to monitor the molten glass temperature and control the forehearth zone temperatures. The annealing lehr’s temperature control zones must be properly monitored and controlled to keep product quality high. If the glass containers are too hot when they leave the lehr, they can mar at the next processing step or crack when they meet the cooler air outside the lehr. If they cool too fast inside the lehr, cracking or breaking can occur. Also, bottles and containers must be at the proper temperature if the glass receives a cold end surface treatment. Sensors mounted over each of the annealing lehr’s temperature zones can accurately monitor and control the cooling process and cold end surface treatment. This allows better quality control and fewer rejected pieces. 

Glass Fiber    

There are two main processes for making glass fiber: crown wool and white wool. The crown wool process is shown in Figure 4. Forehearth zone temperatures are monitored and controlled by infrared fiber optic sensors. This allows the engineer to maintain the optimum molten glass temperatures (viscosity) as it enters the fiberizer (spinner). The spinner temperature is monitored by a fiber optic IR sensor or an ES150 system to maintain consistency of the fiber glass strands and to prevent the spinner holes from clogging. Clogged holes can cause glass “slugs” to enter the glass mat. Hot glass slugs can ignite the backing paper of insulation many days after production is complete. At the curing oven, proper temperature control must be maintained or the binding agent will not cure properly. If paper and/or foil is glued to the glass fiber after curing, the fiber must be at the correct temperature for the material to properly adhere. Sensors are mounted along the conveyor line to monitor temperatures before and after the curing oven. Based on temperature feedback, an engineer can monitor and adjust furnace and curing oven temperatures. For automatic adjustments, sensors are connected directly to the control room. An ES150 is positioned after the curing oven to monitor drying uniformity and identify potentially dangerous glass slugs across the entire width of the product. With infrared sensors in place along the forehearth, conveyor belt and curing oven, the production line moves along more efficiently and high quality is maintained. 

Other Processes     

Other processes that can benefit from Raytek infrared sensors include automotive windshield production, where the reheating and forming sections can be monitored and controlled by MP150 linescanners or Thermalert sensors (see Figure 5). In the production of laminated safety glass, which is used in both vehicles and buildings, GS150/GS150LE systems are positioned to ensure that temperatures are at the proper levels for laminate adhesion. Any glass-related industry where heat is a factor in quality production can use Raytek noncontact infrared sensors for monitoring and controlling the process. 

Products for the Glass Industry 

Dpstar provides a wide range of infrared products for the glass industry. All sensors are easily customized to fit your application. Measure temperatures of hot, moving, or inaccessible materials safely, accurately and with repeatability you can count on. 

Marathon Series
Combining superior performance with state-of-the-art digital technology, the Marathon Series is a family of infrared pyrometers designed for harsh operating environments. These integrated sensors offer advanced electro-optics, video monitoring and image capture capability, a variable focus option and a built-in user interface in a rugged, compact housing.

MP150 Linescanner
The cost-effective way to measure edge-to-edge temperatures for control of product uniformity. Provides data for up to 1024 points per scan, 48 scans per second, in a 90° field of view. With DataTemp DP Windows software for the linescanner, remote temperature monitoring, remote scanner configuration, and data analysis is at your fingertips. View real-time and saved thermal images, and correct process irregularities before they become problems. Based on the MP150 unit we provide the following special application solutions. GS150–thermal imaging and analysis for defect detection and quality improvement in glass annealing/tempering and glass bending processes.

GS150LE
Based on the GS150; this system has added sensors and temperature correction for low emissivity glass. ES150–automated inspection system for detecting, measuring, and classifying defects occurring in sheet extrusion, cast film and other continuous web processes. Raynger 3i Plus Series–portable infrared thermometers for high temperature applications. Superior Distance-to-Spot (D:S) ratio allows users to measure high temperature targets from longer distances, ensuring accurate temperature readings and operator safety.

Advice tailored to your needs

With our comprehensive experience in the glass industry, we can deliver top-quality engineered solutions for every stage of your glass manufacturing.

Dpstar Group
No 35, Jalan OP ½, Pusat Perdagangan One Puchong,
Off Jalan Puchong, 47160 Puchong,
Selangor Darul Ehsan, Malaysia.
Email: [email protected]