Infrared Application of the Month #1: Heating and Forming of PE Tubes
A worldwide manufacturer of polyethylene (PE) tubes had been using a ceramic oven for heating and forming of the tubes. The company was dissatisfied with that method, as heating was not homogeneous, and heat-up time was long (5 minutes). A half-cylindrical oven featuring shortwave IR technology form Heraeus Noblelight afforded easy temperature adjustment, work time of less than two minutes, and improved product quality through reduction of material stress during heating.
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Infrared Application of the Month #2:
Infrared for PV Cell Manufacture
Infrared technology from Heraeus Noblelight is of critical importance to the growing PV (photovoltaics) industry. The manufacturing process for PV involves extreme conditions; many processes operate in vacuum or under high pressure. Acids, leaches and other chemical substances are necessary for PV production. Infrared heat is an effective tool in the application of anti-reflective layers as well as the manufacturing process of the thin film solar cells themselves.
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Tech Center Spotlight:
Mediumwave IR Heaters
Plastics, water and other solvents absorb medium wave radiation especially well. The use of medium wave infrared heaters helps in the effective drying of paints and lacquers and in the economical processing of plastic foils and sheet. Because of their long life, these heaters are best suited for continuous process. Surface films and very thin materials are heated up extremely efficiently.
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Special Designs:
Spiral Heaters
With heaters in spiral form discs, tubes or rods made of plastics, metal or glass can be heated homogeneously. Compared with conventional heating methods, spiral heaters can provide savings in energy, time and costs. Heraeus offers a wide range of heaters for special applications.
Click HERE to download a brochure on Heraeus spiral heaters.
A wide assortment of other special design heaters is available from Heraeus. Click HERE for details.
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Technical Learning: Workpiece Characteristics and Their Effects, Part 2
Effect of power intensity
The flexibility of the corridor type of oven to change the heating condition significantly by
altering power intensity can be used to good effect in several ways. For example, reduced
power intensity is more suitable for workpieces of mixed gauges. Different heat settings
along the length of an oven may suit the curing of certain solvent-based coatings. The heat
transfer falls with distance as an inverse linear law, that is heat flux is inversely proportional
to wall separation.
Effect of conductivity
No significant temperature differences can be expected to occur when heat at the level
experienced in an infrared corridor oven flows into the core of a heavy metal item or across
a section heated on one side only.
Effect of product rotation
For the general case the number of revolutions made by a workpiece or loaded jig while in
the oven is the important criterion rather than the speed of rotation. A value of
approximately 10 revolutions produces a very acceptable temperature uniformity which is
comparable with that to be expected in convection oven practice.
Heating time compared to conveyor speed and product thickness
The time required to cure powder coating is virtually proportional to thickness of the
workpiece. A variable speed conveyor provides a method of maintaining maximum
production over a range of metal gauges.
Velocity and temperature of air
The main advantage of introducing fan circulation into an infrared oven is not to increase
heat transfer but to ensure uniform air temperatures from hearth to roof. The natural
tendency for air to stratify into hot and cooler layers is therefore negated. Circulation of air
at or close to the required temperature also has the advantage of optimizing temperature
uniformity on the product. It can also be observed on the trace of the run that the
workpiece starts to heat before entering the oven, This is encouraged by having extended
entry and exit reflective vestibules or doors of a reflective material which can be adjusted
to enhance reflectivity, Even in the open state parallel to the track the doors form an
effective infrared vestibule. For narrow work such as thin sheets they may be almost closed
to enhance heating inside the oven.
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Contest: Win a FREE iPod!
Keep those entries coming!
Readers of Noblelight News know that infrared technology from Heraeus Noblelight offers innovative, efficient solutions to myriad process heating applications. Infrared heat is suited to many challenges.
Now here's a challenge for our readers. This one is aimed at those currently using infrared heat. Submit a brief (100-200 word) summary of your application, with a brief "before" and after" explanation if applicable, and include a photo (jpeg please). Send it to admin@noblelight.net with the subject line "Contest." The winner will be announced in an upcoming issue. Please note that all entries and photographs become the property of Heraeus Noblelight and may be put to promotional/editorial use at our discretion.
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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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