Pultrusion Method

Creating a More Durable All-FRP Product

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The pultrusion process is similar to extrusion with a few key differences. With
extrusion, a homogeneous raw material is forced through a profile die to produce
the end product. With pultrusion, different raw materials (in this case glass fiber
reinforcements and resin) are drawn into a profile die where they are combined
and cured, with a mechanical pulling force applied to the finished product to
draw more raw materials into the die.

This automated process has been used to make FRP profiles since the early 1950's. Universal Pultrusions produces a wide variety of pultruded profiles for architectural and marine applications, and was the first to use the process to produce door panels beginning in 1986. We are still the only manufacturer in the world to make pultruded doors.

Pultrusion produces a door with excellent physical and thermal insulating properties, immunity to corrosion, and easy-cleaning surfaces making them perfectly suited for corrosive and sanitary industrial applications.

Our Door Pultrusion Process
Our exclusive door panel manufacturing process begins with a high-density, closed-cell polyurethane foam core panel. This core reduces the weight of the door without diminishing its strength, and provides excellent thermal performance.

Multiple layers of glass fiber reinforcing fabrics envelop both sides of the core panel as it moves through the process—a woven layer for impact resistance, two layers of random continuous filament for flexural strength, and fine veil top layer to provide a smooth surface finish. These glass reinforcements wrap around the panel edges from both sides to greatly improve structural properties.

An FDA- and USDA-compliant resin fully saturates the glass fiber fabrics before the door panel enters a profile die, where the reinforcements are compressed around the core panel. The resin fully cures around the core as the panel passes through the heated portion of the die. A constant pulling force draws the door panel through the process, and pulls in more materials behind it, in an automated, continuous process.

This process produces a hermetically sealed, incredibly tough door panel free of voids. The FRP has a 65% glass content and completely encapsulates the core to a thickness of 1/8" at the door faces, providing excellent impact resistance, and 9/16" at the stile edges, for secure screw hold.

After cutting the door panel to length, full-width top and bottom rails (also manufactured using the pultrusion process) are bonded to the panel structure to create a completely sealed assembly. The resulting door is light in weight but absolutely heavy-duty, having a monolithic structure that's immune to moisture and corrosive gases or liquids, with the rigidity necessary for industrial-size openings.