Buying Materials: Small Quantities, Dry Fabrics and Tapes
Dateline: 04/14/97One of the most important things any composite manufacturer needs to know is where to buy materials. In this first "Buying Materials" column, I'll show you where to get small quantities of dry fabrics or tapes (unidirectional fibers). These are the materials most often used in small, home-built projects. In later columns, I'll address other types of materials and larger quantities.
Most material suppliers have fairly large minimum orders, especially when it comes to fabrics or fibers. Fortunately, several companies are now happy to sell you materials by the foot or yard instead of the roll. The premiums are not outrageous, but you will have less of a selection. For example, you will probably be limited to only a few weave styles and you may not get a choice of fiber type. A typical catalog description says something like "Carbon Fiber Cloth: Plain weave, 5.7 oz per sq yd, 42 in wide." But which of the more than 100 carbon fibers does that refer to?
The companies that sell these materials tend to target one of three markets: the general composites market; the aerospace market (especially home-built aircraft); and the marine market (small boats). However, they all sell the same materials. There are only a small number of weavers, and an even smaller number of fiber manufacturers. In most cases, therefore, it's safe to shop purely on price.
The following table gives a quick price comparison of the major home-built suppliers:
| Vendor | Glass | Kevlar | Graphite |
|---|---|---|---|
| ACP | 10.20 | 22.00 | 38.00 |
| CST | 6.00/7.70 | 24.67/26.64 | 44.64/48.21 |
| Fibre Glast | 5.45/11.25 | 25.74/33.85 | 30.00/41.80 |
| RAKA | 4.75 | 19.74 | 35.00 |
| Spruce | 5.15 | 24.47 | 33.57 |
| Wicks | 4.70 | 24.04 | 27.64 |
Notes on the table: The fiberglass cloth is an 8.5 oz E-glass plain weave except for Fibre Glast, which is a 10 oz E-glass. The Kevlar is a 5.0 oz plain weave, more commonly known as 285 style. The graphite is 5.7 oz plain weave (T-300 or AS4) except for RAKA, which is a 14 oz plain weave. All prices are in US dollars per linear yard, normalized to a 50 inch width. Some vendors sell by the linear foot, and may have 38 or 42 inch widths. Price ranges indicate discounts for larger volume purchases. Other widths, weaves, weights, and fibers may be available.
If all of these terms confuse you, don't worry: I'll be covering fabric terminology in a future column. In the meantime, the vendor catalogs usually do a good job of explaining the terms.