What are the uses of glass fiber?
Untwisted Roving
The untwisted roving we encounter in daily life has a simple structure, consisting of bundles of parallel monofilaments. Untwisted roving can be divided into alkali-free and medium-alkali types, mainly distinguished by the glass composition. To produce qualified glass roving, the glass fiber diameter must be between 12 and 23 μm. Due to its properties, it can be directly used in the molding of some composite materials, with wide applications in winding and pultrusion processes. It can also be woven into untwisted roving fabrics, primarily due to its highly uniform tension. Furthermore, the applications of chopped untwisted roving are also very extensive.
Untwisted Roving for Spraying
Untwisted roving in fiberglass spraying processes must possess the following properties:
1. Due to the need for continuous cutting during production, it must ensure minimal static electricity generated during cutting, requiring good cuttable properties.
2. After cutting, it should maximize the production of filaments, thus ensuring high filamentation efficiency. Untwisted roving has a high efficiency in dispersing into filaments after cutting. 3. After chopped length, the filament must have excellent coating properties to ensure complete coverage of the mold.
4. To facilitate easy rolling and air bubble removal, rapid resin impregnation is required.
5. Due to the different spray gun models, the filament thickness must be appropriate for each spray gun.
SMC Untwisted Roving
SMC, also known as sheet molding compound, is widely used in everyday life, such as in automotive parts, bathtubs, and various seats. In production, there are many requirements for SMC untwisted roving, including good chopped length, good antistatic properties, and minimal fuzz to ensure the quality of the resulting SMC sheets. For colored SMC, the requirements for untwisted roving are different; it must easily impregnate in resins with high pigment content. Commonly used SMC untwisted roving is 2400 tex, although 4800 tex is also used in some cases.
Untwisted Roving for Winding
The winding method was developed to produce fiberglass pipes and tanks of varying thicknesses. Untwisted roving for winding must possess the following characteristics:
1. It must be easy to form into a strip, typically ensuring a flat strip shape.
2. Since untwisted roving is prone to unwinding when unwinding from the bobbin, its unwinding properties must be excellent, and the resulting filaments should not be messy like a bird's nest.
3. Tension should not fluctuate significantly, and sag should be avoided.
4. The linear density of the untwisted roving must be uniform and less than a specified value.
5. To ensure easy wetting when passing through the resin bath, the untwisted roving must have good impregnation properties.
Untwisted Roving for Pultrusion
Pultrusion is widely used in manufacturing various profiles with consistent cross-sections. Untwisted roving for pultrusion must ensure a high glass fiber content and unidirectional strength. Pultrusion rovings used in production are made by combining multiple strands of raw yarn; some may also be direct rovings, both are acceptable. Their other performance requirements are similar to those of wound rovings.
Weaving Rovings
In daily life, we see woven fabrics of varying thicknesses or rovings in the same direction, which demonstrate another important use of rovings: weaving. The rovings used are called weaving rovings. These fabrics are primarily used in hand lay-up fiberglass molding. For weaving rovings, the following requirements must be met:
1. Relatively abrasion resistant.
2. Easy to form into ribbons.
3. Because it is mainly used for weaving, a drying step is necessary before weaving.
4. Tension must be uniform and not fluctuate wildly. Certain conditions must be met regarding drape.
5. Good unwinding properties.
6. Ensure easy resin wetting when passing through the resin tank; therefore, good impregnation is essential.
Preform Roving
The preform process, simply put, involves pre-forming the material and then proceeding through appropriate steps to obtain the finished product. In production, we first chopped the untwisted roving and sprayed it onto a mesh of a predetermined shape. Then, resin was sprayed on and used for setting. Finally, the set product was placed in a mold, resin was injected, and it was hot-pressed to obtain the finished product. The performance requirements for preform roving are similar to those for spray-applied roving.
Fiberglass Untwisted Roving Fabric
There are many types of untwisted roving fabrics, with woven fabric being one of them. In hand lay-up fiberglass processes, woven fabric is widely used as the most important substrate. To enhance the strength of the woven fabric, the warp and weft directions must be changed, making it a unidirectional woven fabric. To ensure the quality of the woven fabric, the following characteristics must be guaranteed.
1. For fabrics, the overall surface must be flat, without any bumps, and the edges and corners must be straight, with no stains whatsoever.
2. The length, width, weight, density, etc., of the fabric must meet certain standards.
3. The fiberglass filaments must be neatly wound.
4. The fabric must be able to be quickly impregnated with resin.
5. The dryness and moisture content of the various products woven from the fabric must meet certain requirements.