Dip thermocouples degrade quickly during casting due to intense heat, corrosion, and mechanical wear, leading to inaccurate temperature readings, frequent replacements, and increased process costs.
Image Credit: Optris GmbH
Inaccurate readings can lead to casting flaws, energy waste, and reduced efficiency due to insufficient control of molten metal temperature during pouring.
Solution
Short-wavelength infrared cameras allow for precise, real-time temperature monitoring of molten metal without physical contact.
By taking thermal images of the liquid metal stream, they can take quick remedial action, improve process control, and maintain consistent quality while reducing reliance on disposable sensors and minimizing operational disruptions.
Benefits
- Prevents defective or partial castings, leading to lower scrap rates
- Reduces operational costs by avoiding regular thermocouple replacements
- Improves worker safety with non-contact temperature monitoring
- Improves casting quality through real-time thermal imaging
- Continuous heat data provides seamless automation and improved control
Overcoming the Limitations of Dip Thermocouples in the Casting Process
Casting is a metalworking method in which metal is heated to a liquid state and then poured into a mold, usually in a crucible.
The mold has a negative impression of the desired shape, which allows the metal to solidify as it cools, resulting in the final casting. This technology is very useful for creating intricate shapes that would be difficult or especially expensive to make using other methods.
Casting has advantages such as high surface quality and low material waste, but it also incurs large expenses, especially for mold tooling and the energy needed to heat the metal.
As the metal cools in the ladle, its temperature gradually falls with each additional pour. If the temperature falls below a crucial level, the casting may be incomplete, resulting in flaws. In such circumstances, the damaged portion must be discarded, losing the energy expended during the process.
To avoid this, it is critical to monitor the casting temperature and stop the process if the molten metal falls below the recommended level. If necessary, the metal can be warmed to guarantee proper casting.
Traditionally, companies buy dip thermocouples as consumables every year, but these thermocouples degrade quickly at high temperatures. Thermocouples frequently fail during the casting process due to harsh conditions, including intense heat, corrosive environments, and physical wear from prolonged use.
The extreme heat might cause the thermocouple's protective coating to deteriorate or melt, exposing the sensor elements and resulting in failure. Continuous immersion in molten metal can also cause chemical reactions that degrade the thermocouple's materials, decreasing its lifespan.
In addition, mechanical damage from handling and the harsh casting environment contributes to frequent failures, making thermocouples less reliable for accurate, long-term temperature measurement.
Short-Wavelength Infrared Cameras: The Key to Accurate Liquid Metal Temperature Measurement
An infrared camera is essential for optimizing the casting process, as it provides real-time temperature monitoring, ensuring the molten metal remains within the appropriate temperature range. This level of precision greatly reduces the likelihood of flaws such as incomplete casting or solidification shrinkage.
The camera captures detailed temperature data, enabling quick adjustments that minimize costly errors and reduce material waste. It also checks the cooling rate to ensure uniform solidification and high-quality surface finishes.
Measuring the temperature of liquid metal using long-wavelength infrared cameras is difficult due to the metal's high reflectivity and variable emissivity, which can lead to inaccurate measurements.
Short-wavelength infrared cameras, such as the PI 1M or Xi 1M, offer a more effective approach by making use of the metal's increased emissivity at shorter wavelengths and the exponential growth in infrared light at those wavelengths.
This method produces more accurate temperature measurements, delivering consistent results even in the most demanding metal-casting settings. The PI 1M infrared camera excels at non-contact measurement of the liquid metal stream during pouring, enabling accurate monitoring throughout the casting process.
Its high image quality and ease of automation make it an excellent candidate for integration with programmable logic controllers (PLCs), which can process heat data to find the best stopping locations in the operation. This seamless integration of technology improves the productivity and safety of metal casting.
The camera can also be supplied with a cooling jacket to protect it from dust and dirt, allowing it to operate consistently at temperatures up to 315 °C. The built-in fail-safe mechanism adds security by detecting issues like broken cables, computer shutdowns, and program breakdowns, making it an effective safety feature.
The infrared camera's imaging power far outperforms that of handheld pyrometers, as it automatically detects the hottest or coldest temperatures in the measurement field.
Unlike pyrometers, which only measure one spot, the infrared camera ensures operators do not overlook essential low temperatures, providing a comprehensive and precise temperature profile that improves process control and product quality.
Affordable Infrared Imaging: The Competitive Edge of Optris Cameras
In this application, a metal casting foundry sought a better way to accurately measure the temperature of liquid metals while minimizing reliance on costly disposable dip thermocouples.
The company had purchased thousands of these thermocouples each year, resulting in significant recurrent expenses.
The goal was to create a safer, more cost-effective way to improve the quality of molten metal while saving significantly on consumables. The PI 1M infrared camera enabled the plant to considerably reduce its reliance on disposable thermocouples.
The PI 1M provides precise, non-contact temperature measurement, increasing safety and efficiency while improving metal quality, resulting in significant cost savings.
The Optris infrared camera's competitive pricing allowed the investment to pay for itself within the first year of operation.
Optris offers infrared cameras at very reasonable prices, making advanced thermal imaging technology available to the metal sector. Despite their low cost, Optris infrared cameras retain high quality and performance criteria.
This cost-effectiveness and advanced functionality balance allows organizations to include comprehensive temperature monitoring into their processes and increase automation without exceeding budget limits.
The low cost of Optris infrared cameras makes them an appealing option for companies wishing to transition from old temperature measurement methods to more modern, non-contact solutions.
This information has been sourced, reviewed and adapted from materials provided by Optris GmbH & Co. KG.
For more information on this source, please visit Optris GmbH & Co. KG.