Tuesday, March 11, 2014

Be Gone, Heater Bands!

Processing molten plastics (such as in extrusion or injection molding) is not for the impatient. If you want to do something fast with polymers, look into UV curing or solvent coating or something else where you aren't working with just a bulk, molten polymer. High polymers possess both a high heat capacity and low heat conductivity so that getting the pellets to melt in the first place and then reach a (more or less) uniform temperature throughout the equipment takes a lot of time. Working with (relatively) large machinery doesn't help either, as even though metal has a low heat capacity and high conductivity, melt processing equipment is still made from large pieces of metal that take time to initially heat up. The end result is this: anytime I've ever had to work with the production extruders, it was always a great time to make a huge dent on that stack of papers I've been wanting to read and never had the chance.

Most people do not have such a stack so for them, anything that can be done to speed along heating can be a tremendous boon. Plastemart is reporting that Nordson XALOY has developed a new heating system that is appears to be a faster and more effective alternative to the band heaters traditionally used.
"The ... system consists of two layers of plasma-sprayed metallized ceramic with a nichrome wire wrap sandwiched in between, plus a thermal insulation cover. Because the heat from the wires is conducted throughout the ceramic material, the system raises the temperature of a machine component to target levels more quickly than with band heaters, maintains it more uniformly, and uses less energy. The tightly strapped thermal insulation wrap over the ceramic coating virtually eliminates heat losses to the workplace, saving on air conditioning costs and reducing the risk of operator injury."
While this is limited to barrels and pipes (you're still on your own with dies), any gain in efficiency will be helpful. You just need to recognize that when this heater fails, you are looking at a replacing the whole part (only after disassembling much of the equipment to access the piece) rather than just slapping on another external heating band. But given all the bad experiences I've had with heater bands conking out at the worst possible moment (Thank you, Mr. Murphy!), I'd be seriously interested in seeing how this heating system performs.

Previous Years
March 11, 2013 - What's Wrong with this Picture?

March 11, 2010 - Qualitative Science

March 11, 2009 - The "Most Admired" Chemical Company

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