For license: pultrusion with insulating core.

A specialized pultrusion process developed to make thermally insulating window and door frames is now available for license from Owens-Corning Fiberglas Corp., Toledo. The company's Fibron technology has been used to make FRP windows commercially for three years now, and last year patio doors were added to the line. The products are made on a handful of lines at a plant in Hazelton, Pa., and an R&D/demonstration line operates at the company's Granville, Ohio, research center. Windows are assembled at Martinsville, Va.

Owens-Coming is willing to license Fibron technology for producing window lineals or other cored products. Licensing would involve transfer of "significant know-how" for the process, but no proprietary equipment is involved, says v.p. of technology and business development Dennis Barber. (Owens Coming now also offers lineals to other window fabricators.)

PROCESS OVERVIEW

Owens-Corning calls its process "CLM" or "continuous lineal molding." It's basically pultrusion over an insulating core of dense glass wool. The steps in the process are as follows:

* Pre-shaping the core. Owens-Corning manufactures glass-wool boards as a standard product, 4 ft wide x 8 ft long. These are shipped to the Hazelton plant and cut with a saw into rectangular blanks. These blanks are run through a wood-milling machine to impart an exact profile corresponding to the overall shape of the final lineal. The dense wool board is capable of being milled into quite intricate shapes, says a company engineer. Finally, the milled boards are glued together end to end, making a continuous core profile.

* Sealing the core. As the milled cores first enter the CLM process, glass rovings are placed longitudinally on the surface of the core to give it machine direction strength, and polyester surfacing veil is wrapped around the reinforced core. Addition of the machine-direction rovings enabled doubling the line speed (up to 7 ft/min, depending on the profile), since the glue holding the core sections together tended to break. (Owens-Corning continues to increase line speeds, Barber says.)

Next, the reinforced core passes through a resin-injection die, where the glass veil and rovings are impregnated with liquid polyester resin. This effectively seals the surface of the core.

* Applying the skin. In the following stage, continuous-strand mat and more surfacing veil are applied to the core to form the main surrounding structure of the profile. Owens-Corning has learned through trial and error how to fabricate polypropylene folding dies to fold the mat into tiny kerfs in the core profile and wrap it completely and tightly around the core. A second resin-injection die impregnates and cures the skin.

* Finishing. After curing, the profile is corona treated in-line to enhance adhesion of a weatherable coating. At present, a two-part urethane liquid paint from Sherwin-Williams Co.'s Chemical Coatings Div., Cleveland, is sprayed electrostatically off-line. But Owens-Corning is developing methods for in line finishing, the most likely near-term candidate being powder coating with an acrylic paint. This requires a preheat oven to warm the profile surface and then a curing oven to melt the powder coating.

For its Granville R&D line, Owens-Coming uses a Pulstar 2408 pultrusion machine from Pultrusion Technology, div. of MMFG, Twinsburg, Ohio. Barber says this would be an appropriate machine for production use.

The company's Fibron production lines run 24 hr, seven days a week. Multiple dies can be run side by side using a single puller and programmable indexing saw. Although Owens-Corning has not done so in production yet, Barber says running multiple dies would be a cost-effective way to increase capacity in the future. Even different profiles can be run side by side, though some puller modification would be required.