A manufacturer of extruded rubber seals for the automotive industry needed a curing system that:

  • Brings instant on/off heating capabilities.

  • Cures the coating in as little as 30 sec.

  • Is capable of completely surrounding the product, or be flexible enough to cure just one coated side, if that is all that is required.

A demanding application, but one that infrared can handle.

The rubber seals are used on doors, trunks and hatchbacks/lift gates to provide an airtight and watertight seal. The manufacturer applies a water based “low friction” coating to help reduce annoying rubbing noises and squeaks, and to prevent ice from accumulating that can cause the doors to freeze.

The seals are offered in many sizes and types to suit the range of vehicles on which they are used. The varying design characteristics of the seals means that they require various heat and power densities, as well as a range of line speeds (from 30 to 80 ft/min, typically), to adequately cure the coatings.

Testing performed at an IRED member's test laboratory enabled the seals manufacturer to experiment with various configurations, watt densities, infrared heat sources and line speeds. The most flexible system proved to be short-wave electric infrared using T3 quartz lamps. They require little heatup, quickly respond to process changes and can be de-energized instantly if needed. Cure times in as little as 30 sec were also achieved.

The oven configuration, which employs infrared on all four sides of the seal, allows the product to be completely surrounded by heat or, if the entire seal is not coated, allows the infrared to be focused on only the side or sides of the seal that have been coated. A clam-shell oven design with pneumatic cylinders was also employed to allow the system to open and close around the product, and allow for ease of maintenance.

Lastly, the systems were designed with multiple heat zones utilizing SCR power controllers. The output of each zone is infinitely variable from 0 percent to 100 percent, allowing the manufacturer to match the heat output to the requirements of the curing process.

IRED Spotlight Project

Product
Rubber seals used on doors, trunks and hatchback/lift gates to provide an air- and water-tight seal

Challenge
Wide range of sizes and types of seals, which requires various heat and power densities, demands flexible heating system

Solution
Clam-shell short-wave infrared oven

Benefits and Payback

  • Faster line speeds

  • Less maintenance

  • Fewer product defects or damage. The product will not overheat if the line stops because the T3 lamps are virtually instant-off.

  • Dependable results through precise control

  • Ability to focus the heat at the exact areas to be cured

  • Lower operating costs by heating just the areas that require a cure

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