Infrared Application of the Month #1:
Process Heat for Mirror Coating
Over time, a mirror manufacturer realized that their means of generating heat for the mirror coating process was slow, inefficient and burdened the company with a high energy cost. They replaced their longwave heaters with mediumwave infrared heaters from Heraeus Noblelight. Once installed, the proportionally-spaced infrared lamps reduced energy consumption while providing a more reliable heat source. The end result was higher productivity and lower production cost.
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Infrared Application of the Month #2:
Applying Glue to Metal Can Lids
One critical step in a processor's canning production line was the application of glue to can lids. The previous method -- hot air -- was time-consuming and inefficient: it heated a large volume of air when what was needed was direct, specifically targeted heat. Heraeus Noblelight provided a solution in their mediumwave infrared heaters. Infrared heat is focused directly where it is needed, providing both efficiency and effectiveness.
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Tech Center Spotlight:
Shortwave Twintube Heaters
Shortwave IR heaters from Heraeus are suitable for all applications in which the attainment of high temperatures in the shortest possible time is what counts. Their emission maximum is between 0.9 and 1.6 micron. Among their advantages are high radiation density in the most compact space, and low space requirements.
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Special Designs: Slot Heater
Infrared heater with a slot in one of the tubes, working like a drying channel for fibers or ropes. Twin tube made of quartz glass, gold coating around the whole heater. Fast response medium wave heater. The special slot design makes drying very intensive and efficient.
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 2 of 3
Technical Learning Q&A: A Comparison of Convection vs. Infrared, Part 2 of 3
continued from last month's issue...
Q: Is it possible to cure/dry large conductive components like engine blocks?
A: A slow rate of heat transfer from air allows heat to conduct into components leading to long heat up times. Using infrared emitters with a high transfer of energy enables surfaces to be heated more rapidly overcoming conduction losses.
Q: What about the noise?
A: Large convection ovens generate a lot of noise from fans and air movement or turbulence. This causes health and safety implications. Infrared ovens with low air movement cause less noise.
Q: Can you heat in vacuum?
A: With convection it is not possible. Infrared emitters can be used to heat components in a vacuum chamber.
Q: What happens in a "dirty" environment?
A: Combustion products, recirculation of dust etc. make convection unsuitable for "clean" applications. Infrared heat is clean, no combustion products and no need to recirculate air.
Q: What can you say about adjustable control?
A: Difficult and expensive with convection (more air nozzles) at different air temperature and air speed. It is easy to achieve infinitely adjustable control with infrared emitters by selection of energy densities, wavelengths, and variable power levels.
Q: How well does it heat three-dimensional shapes?
A: Convection has an edge with even heating especially with radical 3 dimensional geometry. Circulated hot air will cause all surfaces reach the same temperature. Infrared has advantage on 2 dimensional parts and heats by line-of-sight. "Hidden areas" will be heated only by conduction through the material. It should be noted that metallic parts conduct heat very rapidly to hidden areas, and a properly designed IR oven uses a "booster" section up front and gives the part soak time to conduct through the part. Even so, process times can be considerably faster with a booster and soak section than with convection alone. Many manufactures now combine both technologies – booster and convection – to get the best of both technologies.
Q: How about holding part temperature?
A: Convection oven at 200 degrees C air temperature will hold part at temperature without this temperature being exceeded, but limited in maximum air temperature only. Holding with infrared employs electrical controls to prevent temperature increasing or decreasing, generally from a closed loop automatic system.
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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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