Thermal cameras aid process optimisation and monitoring

IMPAC Infrared has supplied temperature measurement systems for almost 50 years and the company's digital pyrometers are renowned for their quality and performance. In recent years there has been an increase in the requirement to obtain more data than is available from a single-spot pyrometer; this need has seen the introduction of newer technology to the temperature market. Thermal Imaging is therefore becoming an increasingly accepted technology for temperature analysis, as it can provide significant benefits to the user, particularly in R&D areas and for process optimisation.

Thermal Imaging has traditionally been a high-cost option and has consequently only been used for applications where the cost can be justified. However, developments in thermal imaging have seen dramatic price reductions for portable cameras, with low-resolution cameras falling to below £4000. While these cameras do not have the resolution required for process optimisation, the introduction of these low-cost units has helped to stimulate and educate the market about the benefits of thermal imaging.

As a market leader, IMPAC Infrared has responded to this new demand and has developed a comprehensive range of online thermal imaging cameras aimed at the R&D and process optimisation sectors. These cameras are cost-effective and, together with a comprehensive suite of software packages, ensure quick and easy analysis of the process temperatures.

IMPAC's range of cameras is split into three sections:

• HS-Vision Series: For automatic detection of thermal anomalies (hot or cold spots)
• TG-Vision Series: For R&D and light industrial applications
• ID-Vision Series: For harsh industrial environments

Each series of cameras is complemented with a suite of software packages:

• RTV Basic: For data recording and visualisation of thermal data
• RTV Analyser: For full analysis of thermal data plus data export
• RTV Control: For full analysis of thermal data and I/O functions for process control

The cameras have a selection of wavebands to suit various applications:

• 8-14um for general purpose measurements on non-metal surfaces
• 5um for glass surface temperature measurements
• 3.9um for measurements through flames and hot gases
• 3-5um for measurement of metals and ceramics at lower temperatures (>150degC)
• 1um for measurement of metals at high temperatures up to 2500degC

For applications where target sizes are very small or distance are very long, a number of optional wide-angle, macro and telephoto lenses are available.

Some examples where online cameras have been used are as follows:

Plastic injection moulded components

For this application the quality of the moulded component depends essentially on the design of the tooling (heating and cooling system). Temperature uniformity is vital for achieving tight tolerances throughout the mouldings in the various cavities.

Using a thermal imaging camera enables the operator to detect weak points when commissioning new moulds and to find the optimum temperature control set-up.

Bulb filament

In addition to a long service life, good luminance is one of the critical quality requirements in light bulb production. To obtain optimum luminance, the temperature distribution optimised prior to starting production.

A thermal imaging camera with a resolution of 640 x 480 pixels provides detailed and informative measurements of the filament. To ensure that only the filament is scanned and not the glass envelope, a short-wavelength camera is used.

Induction heating

To ensure the optimised hardening of the metal surface, the component has to be rapidly heated to the correct temperature for a defined period of time. The resulting quality and durability of parts are influenced significantly by the temperature before being quenched.

A thermal imaging camera is used for process optimisation for setting heating speed and generator power levels. The camera measures the full component and enables the user to make adjustments to the various parameters to ensure the correct heating patterns. Once optimised, a single-point pyrometer is sufficient for day-to-day control of the heating process.

Molten steel 'torpedo' ladle

The torpedo ladle is used to carry molten iron around the steelmaking plant. These ladles can carry 300 tons of molten iron and consequently operate under stringent operating conditions. The ladles are lined with refractory material and, over time, this lining wears and if not carefully monitored the hot metal could cause a breakout through a weakened area. The results of a breakout could be catastrophic, with significant risk to personnel and, of course, result in a major loss of plant equipment and production capacity.

Thermal imaging cameras are utilised to continuously monitor the venerable areas of the torpedo ladle and automatically log the temperature data of each unit. Should a ladle start to show signs of refractory wear and the outer surface temperature rise above the acceptable limit, then the camera software will automatically raise an alarm so that addition temperature checks can be made and, if necessary, the ladle can be withdrawn from service before any problem arises.

The examples above are only a few of the many applications where thermal imaging cameras can be used for plant monitoring and process optimisation.