Infrared Application of the Month #1:
Curing Paste in Lightbulb Reflector Sockets
A manufacturer of light bubs for industrial and consumer applications uses shortwave IR technology for curing of the paste used to fix the lamps in their sockets. In this application, IR technology proves superior to the previous method (a hot air oven) through focused --and thus more efficient -- heating of the socket. The paste is heated to 250°C while the bulb reflector reaches temperatures of no more than 100°C. Production speed is also increased significantly.
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Infrared Application of the Month #2:
Reducing Residual Moisture in Cotton Tissue
A manufacturer of fashion tissue employs a carbon twin-tube IR heating system to reduce moisture from 7% to 1% in their product. A double-sided heating system is used, with three-zone power control for maximum flexibility. Homogeneous drying is achieved, even with a line speed of 100 meters per minute. The IR system did not require changes to the machine's configuration, and the resulting product is colorfast and free of unwanted color gradations.
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Tech Center Spotlight:
Carbon IR Heaters
These IR heaters use a carbon ribbon as the heating element. With very fast heating times (>2 sec), they are especially suitable for processes where the heat must be switched on and off quickly. The spectrum is the same as medium wave infrared heaters, so carbon heaters are efficient for heating plastics and for drying processes.
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Special Designs:
Hybrid Carbon/Shortwave Heaters
These offer all of the benefits of Carbon and Shortwave heaters using Heraeus' proven twin-tube design. The result is homogenous heating, perfectly matched to the application. Unlike pure carbon heaters, the voltage can also be adjusted. This heater is ideal for applications requiring different absorption spectra or depths of penetration, within the same product. Applications include drying of printed tissues; toner fixing; simultaneous cooking and browning of foodstuffs and many others.
A wide assortment of special design heaters are available from Heraeus. Click HERE to for details.
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Technical Learning Q&A: A Comparison of Convection vs. Infrared
Part 1 of 3
Q: How does heat transfer differ between convection and IR?
A: Convection can only be controlled by air temperature and airspeed. With infrared emitters, a far greater flexibility in heat up rates and temperatures can be achieved using different energy densities and wavelengths.
Q: How do the technologies compare with regard to energy efficiency?
A: Convection can waste a lot of energy when switching from large to small components. Infrared emitters can target energy specifically to areas that require heating.
Q: How long are the reaction times of the heating systems?
A: With a convection oven, reaction time may take 30 minutes to 2 hours depending on the size of the oven, so an oven will be left running all-day even when there is no production. Infrared emitters can be switched on and off within seconds to suit production conditions.
Q: How does mass affect the heat-up rate?
A: In convection oven the heat up rates will be influenced by mass (number) of components. Infrared is an "energy source" and is not influenced by the number of components in the oven.
Q: How much space is required?
A: Convection takes up a large amount of floor space. Infrared is much more compact, typically 1/4 to 1/3 the space.
Q: What maintenance costs are associated with each technology?
A: Convection requires frequent maintenance (fans, filters, pipes, seals, burners) and full maintenance normally requires a complete strip down of the oven. Infrared systems typically require only minor maintenance (e.g. changing of emitters or filters).
Q: How is temperature controlled when parameters change?
A: For convection ovens it takes a long time to reduce or raise the air temperature to suit changing line conditions. IR emitters can be regulated instantly to changing conditions; a closed loop control via speed or temperature is possible.
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That's it for this month's issue of Application Notes for IR Heating. Feel free to encourage your colleagues to subscribe. Just click HERE to send them an invitation to subscribe. It's quick, easy, FREE, and no-obligation.
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