PULTRUSION: Preheater Speeds Up Production Rates

Preheater speeds up pultrusion of thick shapes by three to five times.

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Radio Frequency Co.’s, Millis, Mass., new Macrowave Radio Frequency (RF) Pultrusion Preheater warms thermoset pultruded shapes to 150 to 170°F, allowing pultrusion speeds of thick shapes at rates three to five times faster then achievable without RF preheating.


The Macrowave RF Preheater works by creating an alternating electric field between two electrodes. The material to be heated is conveyed between these electrodes, where that alternating electric field reverses its polarity 90 million times/second and causes the polar molecules in the thermoset resin to continuously reorient to face opposite electrodes. Friction resulting from this molecular movement causes the material to rapidly heat throughout its entire mass.


Heating occurs instantly and uniformly throughout the mass of a homogeneous material, and the supplier says no temperature differential is required to force heat via conduction from the surface to the center as in convection, contact or infrared heating processes


Radio Frequency Co. adds that the Macrowave RF Preheater automatically responds to changes in pultrusion speed, preventing pre-gelling of the pultrusion resin.