COFAB© KNITTED FABRICS
COFAB© fabrics are the only true knitted fabrics in the FRP industry. When the original company was started in the 1970's, all of the knitting machines developed by Rockwell International were delivered to this facility. Other manufacturers advertise knitted products, but in actuality, they are a stitched or sewn fabric which do not have the characteristics found in COFAB©. The fabrics are manufactured by knitting a jersey stitch with a fine denier polyester yarn and simultaneously inserting glass warp and weft rovings into the knit yarn matrix. The fabric is knitted in a 150" circumference tube and then split down into desired roll widths.
Fabrics are available in four (4) types of construction groups: BIAXIAL, WARP UNIDIRECTIONAL, WEFT UNIDIRECTIONAL and POLYMER CONCRETE. The first three (3) are conventional type fabrics. However, the polymer concrete group is very open which allows the large aggregate to freely flow through the fabric.
As previously mentioned, COFAB© is the only true knitted fabric in the FRP industry. The polyester stitch yarn holds the glass matrix in place while at the same time allowing the strands to move without gaping. This feature is what makes COFAB© conform so well into both inside and outside corners and tight angles. When the fabric is molded on uneven objects, it conforms to mold the shape exceptionally well. Also when formed around sharp external corners, you get no gapping of the fabric.
With COFAB© fabrics you do not get the fall out of small fibers that you do with those that are stitched. Stitched fabrics are basically sewn fabrics, and the needles fracture some of the glass filaments which then fall out. This is especially troublesome in pultrusion operations because these loose fibers tend to clog up the die. Not only does this tend to clog up pultrusion dies or other equipment, it also lowers the strength of the composite.
With COFAB© fabrics you get superior wet-out. The open channel between both the warp and weft ends create natural canals for the resin to flow in (see photograph on MAIN PAGE). This, in addition to the small openings from the front to back, in conjunction with the physical characteristics of the glass we use, is what gives COFAB© its superior wet-out.
COFAB© fabrics are efficiently compatible with all resin systems.
The fabrics are used in all types of applications. However, the natural channels for the resin to flow through and the excellent conformability makes the fabrics especially beneficial in PULTRUSION and RESIN TRANSFER MOLDING (RTM) applications.