A material consisting of extremely fine glass fibers, used in making various products, such as yarns, fabrics, insulators, and structural objects or parts. Also called spun glass.
fiberglass
Dictionary:
fi·ber·glass (fī'bər-glăs')  |
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| How Products are Made: How is fiberglass made? |
Background
Fiberglass refers to a group of products made from individual glass fibers combined into a variety of forms. Glass fibers can be divided into two major groups according to their geometry: continuous fibers used in yarns and textiles, and the discontinuous (short) fibers used as batts, blankets, or boards for insulation and filtration. Fiberglass can be formed into yarn much like wool or cotton, and woven into fabric which is sometimes used for draperies. Fiberglass textiles are commonly used as a reinforcement material for molded and laminated plastics. Fiberglass wool, a thick, fluffy material made from discontinuous fibers, is used for thermal insulation and sound absorption. It is commonly found in ship and submarine bulkheads and hulls; automobile engine compartments and body panel liners; in furnaces and air conditioning units; acoustical wall and ceiling panels; and architectural partitions. Fiberglass can be tailored for specific applications such as Type E (electrical), used as electrical insulation tape, textiles and reinforcement; Type C (chemical), which has superior acid resistance, and Type T, for thermal insulation.
Though commercial use of glass fiber is relatively recent, artisans created glass strands for decorating goblets and vases during the Renaissance. A French physicist, Rene-Antoine Ferchault de Reaumur, produced textiles decorated with fine glass strands in 1713, and British inventors duplicated the feat in 1822. A British silk weaver made a glass fabric in 1842, and another inventor, Edward Libbey, exhibited a dress woven of glass at the 1893 Columbian Exposition in Chicago.
Glass wool, a fluffy mass of discontinuous fiber in random lengths, was first produced in Europe at the turn of the century, using a process that involved drawing fibers from rods horizontally to a revolving drum. Several decades later, a spinning process was developed and patented. Glass fiber insulating material was manufactured in Germany during World War I. Research and development aimed at the industrial production of glass fibers progressed in the United States in the 1930s, under the direction of two major companies, the Owens-Illinois Glass Company and Corning Glass Works. These companies developed a fine, pliable, low-cost glass fiber by drawing molten glass through very fine orifices. In 1938, these two companies merged to form Owens-Corning Fiberglas Corp. Now simply known as Owens-Corning, it has become a $3-billion-a-year company, and is a leader in the fiberglass market.
Raw Materials
The basic raw materials for fiberglass products are a variety of natural minerals and manufactured chemicals. The major ingredients are silica sand, limestone, and soda ash. Other ingredients may include calcined alumina, borax, feldspar, nepheline syenite, magnesite, and kaolin clay, among others. Silica sand is used as the glass former, and soda ash and limestone help primarily to lower the melting temperature. Other ingredients are used to improve certain properties, such as borax for chemical resistance. Waste glass, also called cullet, is also used as a raw material. The raw materials must be carefully weighed in exact quantities and thoroughly mixed together (called batching) before being melted into glass.
The Manufacturing
Process
Melting
- Once the batch is prepared, it is fed into a furnace for melting. The furnace may be heated by electricity, fossil fuel, or a combination of the two. Temperature must be precisely controlled to maintain a smooth, steady flow of glass. The molten glass must be kept at a higher temperature (about 2500°F [1371°C]) than other types of glass in order to be formed into fiber. Once the glass becomes molten, it is transferred to the forming equipment via a channel (forehearth) located at the end of the furnace.
Forming into fibers
- Several different processes are used to form fibers, depending on the type of fiber. Textile fibers may be formed from molten glass directly from the furnace, or the molten glass may be fed first to a machine that forms glass marbles of about 0.62 inch (1.6 cm) in diameter. These marbles allow the glass to be inspected visually for impurities. In both the direct melt and marble melt process, the glass or glass marbles are fed through electrically heated bushings (also called spinnerets). The bushing is made of platinum or metal alloy, with anywhere from 200 to 3,000 very fine orifices. The molten glass passes through the orifices and comes out as fine filaments.
Continuous-filament process
- A long, continuous fiber can be produced through the continuous-filament process. After the glass flows through the holes in the bushing, multiple strands are caught up on a high-speed winder. The winder revolves at about 2 miles (3 km) a minute, much faster than the rate of flow from the bushings. The tension pulls out the filaments while still molten, forming strands a fraction of the diameter of the openings in the bushing. A chemical binder is applied, which helps keep the fiber from breaking during later processing. The filament is then wound onto tubes. It can now be twisted and plied into yarn.
Staple-fiber process
- An alternative method is the staplefiber process. As the molten glass flows through the bushings, jets of air rapidly cool the filaments. The turbulent bursts of air also break the filaments into lengths of 8-15 inches (20-38 cm). These filaments fall through a spray of lubricant onto a revolving drum, where they form a thin web. The web is drawn from the drum and pulled into a continuous strand of loosely assembled fibers. This strand can be processed into yarn by the same processes used for wool and cotton.
Chopped fiber
- Instead of being formed into yarn, the continuous or long-staple strand may be chopped into short lengths. The strand is mounted on a set of bobbins, called a creel, and pulled through a machine which chops it into short pieces. The chopped fiber is formed into mats to which a binder is added. After curing in an oven, the mat is rolled up. Various weights and thicknesses give products for shingles, built-up roofing, or decorative mats.
Glass wool
- The rotary or spinner process is used to make glass wool. In this process, molten glass from the furnace flows into a cylindrical container having small holes. As the container spins rapidly, horizontal streams of glass flow out of the holes. The molten glass streams are converted into fibers by a downward blast of air, hot gas, or both. The fibers fall onto a conveyor belt, where they interlace with each other in a fleecy mass. This can be used for insulation, or the wool can be sprayed with a binder, compressed into the desired thickness, and cured in an oven. The heat sets the binder, and the resulting product may be a rigid or semi-rigid board, or a flexible batt.
Protective coatings
- In addition to binders, other coatings are required for fiberglass products. Lubricants are used to reduce fiber abrasion and are either directly sprayed on the fiber or added into the binder. An anti-static composition is also sometimes sprayed onto the surface of fiberglass insulation mats during the cooling step. Cooling air drawn through the mat causes the anti-static agent to penetrate the entire thickness of the mat. The anti-static agent consists of two ingredients—a material that minimizes the generation of static electricity, and a material that serves as a corrosion inhibitor and stabilizer.
Sizing is any coating applied to textile fibers in the forming operation, and may contain one or more components (lubricants, binders, or coupling agents). Coupling agents are used on strands that will be used for reinforcing plastics, to strengthen the bond to the reinforced material.
Sometimes a finishing operation is required to remove these coatings, or to add another coating. For plastic reinforcements, sizings may be removed with heat or chemicals and a coupling agent applied. For decorative applications, fabrics must be heat treated to remove sizings and to set the weave. Dye base coatings are then applied before dying or printing.
Forming into shapes
- Fiberglass products come in a wide variety of shapes, made using several processes. For example, fiberglass pipe insulation is wound onto rod-like forms called mandrels directly from the forming units, prior to curing. The mold forms, in lengths of 3 feet (91 cm) or less, are then cured in an oven. The cured lengths are then de-molded lengthwise, and sawn into specified dimensions. Facings are applied if required, and the product is packaged for shipment.
Quality Control
During the production of fiberglass insulation, material is sampled at a number of locations in the process to maintain quality. These locations include: the mixed batch being fed to the electric melter; molten glass from the bushing which feeds the fiberizer; glass fiber coming out of the fiberizer machine; and final cured product emerging from the end of the production line. The bulk glass and fiber samples are analyzed for chemical composition and the presence of flaws using sophisticated chemical analyzers and microscopes. Particle size distribution of the batch material is obtained by passing the material through a number of different sized sieves. The final product is measured for thickness after packaging according to specifications. A change in thickness indicates that glass quality is below the standard.
Fiberglass insulation manufacturers also use a variety of standardized test procedures to measure, adjust, and optimize product acoustical resistance, sound absorption, and sound barrier performance. The acoustical properties can be controlled by adjusting such production variables as fiber diameter, bulk density, thickness, and binder content. A similar approach is used to control thermal properties.
The Future
The fiberglass industry faces some major challenges over the rest of the 1990s and beyond. The number of producers of fiberglass insulation has increased due to American subsidiaries of foreign companies and improvements in productivity by U.S. manufacturers. This has resulted in excess capacity, which the current and perhaps future market cannot accommodate.
In addition to excess capacity, other insulation materials will compete. Rock wool has become widely used because of recent process and product improvements. Foam insulation is another alternative to fiberglass in residential walls and commercial roofs. Another competing material is cellulose, which is used in attic insulation.
Because of the low demand for insulation due to a soft housing market, consumers are demanding lower prices. This demand is also a result of the continued trend in consolidation of retailers and contractors. In response, the fiberglass insulation industry will have to continue to cut costs in two major areas: energy and environment. More efficient furnaces will have to be used that do not rely on only one source of energy.
With landfills reaching maximum capacity, fiberglass manufacturers will have to achieve nearly zero output on solid waste without increasing costs. This will require improving manufacturing processes to reduce waste (for liquid and gas waste as well) and reusing waste wherever possible.
Such waste may require reprocessing and remelting before reusing as a raw material. Several manufacturers are already addressing these issues.
Where To Learn More
Books
Aubourg, P.F., C. Crall, J. Hadley, R.D. Kaverman, and D.M. Miller. "Glass Fibers, Ceramics and Glasses," in Engineered Materials Handbook, Vol. 4. ASM International, 1991, pp. 1027-31.
McLellan, G.W. and E.B. Shand. Glass Engineering Handbook. McGraw-Hill, 1984.
Pfaender, H.G. Schott Guide To Glass. Van Nostrand Reinhold Company, 1983.
Tooley, F.V. "Fiberglass, Ceramics and Glasses," in Engineered Materials Handbook, Vol. 4. ASM International, 1991, pp. 402-08.
Periodicals
Hnat, J.G. "Recycling of Insulation Fiberglass Waste." Glass Production Technology International, Sterling Publications Ltd., pp. 81-84.
Webb, R.O. "Major Forces Impacting the Fiberglass Insulation Industry in the 1990s." Ceramic Engineering and Science Proceedings, 1991, pp. 426-31.
[Article by: Laurel M. Sheppard]
| Columbia Encyclopedia: fiberglass |
fiberglass, thread made from glass. It is made by forcing molten glass through a kind of sieve, thereby spinning it into threads. Fiberglass is strong, durable, and impervious to many caustics and to extreme temperatures. For those qualities, fabrics woven from the glass threads are widely used for industrial purposes. Fiberglass fabrics can also be made to resemble silks and cotton and are used for curtains and drapery. A wide variety of materials are made by combining fiberglass with plastic. These materials, which are rust proof, are molded into the shape required or pressed into flat sheets. Boat hulls, automobile bodies, and roofing and ceiling compositions are some of the uses to which such material is put.
| Boating Encyclopedia: Fiberglass |
Laminating layers of glass and resin to make a boat hull
The most popular boatbuilding material is a mixture of fine glass strands and cured polyester resin known as fiberglass, glass-reinforced plastic (GRP), or fiber-reinforced
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| Wikipedia: Fiberglass |
Fiberglass, (also called fibreglass and glass fibre), is material made from extremely fine fibers of glass. It is used as a reinforcing agent for many polymer products; the resulting composite material, properly known as fiber-reinforced polymer (FRP) or glass-reinforced plastic (GRP), is called "fiberglass" in popular usage. Glassmakers throughout history have experimented with glass fibers, but mass manufacture of fiberglass was only made possible with the invention of finer machine tooling. In 1893, Edward Drummond Libbey exhibited a dress at the World's Columbian Exposition incorporating glass fibers with the diameter and texture of silk fibers. This was first worn by the popular stage actress of the time Georgia Cayvan.
What is commonly known as "fiberglass" today, however, was invented in 1938 by Russell Games Slayter of Owens-Corning as a material to be used as insulation. It is marketed under the trade name Fiberglas, which has become a genericized trademark. A somewhat similar, but more expensive technology used for applications requiring very high strength and low weight is the use of carbon fiber.
Contents |
Fiber formation
Glass fiber is formed when thin strands of silica-based or other formulation glass is extruded into many fibers with small diameters suitable for textile processing. The technique of heating and drawing glass into fine fibers has been known for millennia; however, the use of these fibers for textile applications is more recent. Until this time all fiberglass had been manufactured as staple. When the two companies joined to produce and promote fiberglass, they introduced continuous filament glass fibers.[1] Owens-Corning is still the major fiberglass producer in the market today. The first commercial production of fiberglass was in 1936. In 1938 Owens-Illinois Glass Company and Corning Glass Works joined to form the Owens-Corning Fiberglas Corporation. Two types of fiberglass most commonly used are S-glass and E-glass. E-glass has good insulation properties and it will maintain its properties up to 1500° F (816° C). S-glass has a high tensile strength and is stiffer than E-glass.
Chemistry
The basis of textile-grade glass fibers is silica, SiO2. In its pure form it exists as a polymer, (SiO2)n. It has no true melting point but softens at 2000°C, where it starts to degrade. At 1713°C, most of the molecules can move about freely. If the glass is then cooled quickly, they will be unable to form an ordered structure.[2] In the polymer, it forms SiO4 groups which are configured as a tetrahedron with the silicon atom at the center and four oxygen atoms at the corners. These atoms then form a network bonded at the corners by sharing the oxygen atoms.
The vitreous and crystalline states of silica (glass and quartz) have similar energy levels on a molecular basis, also implying that the glassy form is extremely stable. In order to induce crystallization, it must be heated to temperatures above 1200°C for long periods of time.[1]
Although pure silica is a perfectly viable glass and glass fiber, it must be worked with at very high temperatures, which is a drawback unless its specific chemical properties are needed. It is usual to introduce impurities into the glass in the form of other materials to lower its working temperature. These materials also impart various other properties to the glass which may be beneficial in different applications. The first type of glass used for fiber was soda lime glass or A glass. It was not very resistant to alkali. A new type, E-glass was formed that is alkali free (< 2%) and is an alumino-borosilicate glass.[3] This was the first glass formulation used for continuous filament formation. E-glass still makes up most of the fiberglass production in the world. Its particular components may differ slightly in percentage, but must fall within a specific range. The letter E is used because it was originally for electrical applications. S-glass is a high-strength formulation for use when tensile strength is the most important property. C-glass was developed to resist attack from chemicals, mostly acids which destroy E-glass.[3] T-glass is a North American variant of C-glass. A-glass is an industry term for cullet glass, often bottles, made into fiber. AR-glass is alkali-resistant glass. Most glass fibers have limited solubility in water but are very dependent on pH. Chloride ions will also attack and dissolve E-glass surfaces. A recent trend in the industry is to reduce or eliminate the boron content in the glass fibers.
Since E-glass does not really melt, but soften, the softening point is defined as "the temperature at which a 0.55–0.77 mm diameter fiber 235 mm long, elongates under its own weight at 1 mm/min when suspended vertically and heated at the rate of 5°C per minute".[4] The strain point is reached when the glass has a viscosity of 1014.5 poise. The annealing point, which is the temperature where the internal stresses are reduced to an acceptable commercial limit in 15 minutes, is marked by a viscosity of 1013 poise.[4]
Properties
Glass fibers are useful because of their high ratio of surface area to weight. However, the increased surface area makes them much more susceptible to chemical attack. By trapping air within them, blocks of glass fiber make good thermal insulation, with a thermal conductivity of the order of 0.05 W/(mK).[5]
The strength of glass is usually tested and reported for "virgin" or pristine fibers—those which have just been manufactured. The freshest, thinnest fibers are the strongest because the thinner fibers are more ductile. The more the surface is scratched, the less the resulting tenacity.[3] Because glass has an amorphous structure, its properties are the same along the fiber and across the fiber.[2] Humidity is an important factor in the tensile strength. Moisture is easily adsorbed, and can worsen microscopic cracks and surface defects, and lessen tenacity.
In contrast to carbon fiber, glass can undergo more elongation before it breaks.[2] There is a correlation between bending diameter of the filament and the filament diameter.[6] The viscosity of the molten glass is very important for manufacturing success. During drawing (pulling of the glass to reduce fiber circumference), the viscosity should be relatively low. If it is too high, the fiber will break during drawing. However, if it is too low, the glass will form droplets rather than drawing out into fiber.
Glass-reinforced plastic
Glass-reinforced plastic (GRP) is a composite material or fiber-reinforced plastic made of a plastic reinforced by fine glass fibers. Like graphite-reinforced plastic, the composite material is commonly referred to by the name of its reinforcing fibers (fiberglass). Chemosetting plastics are normally used for GRP production—most often polyester (using butanone as a catalyst), but vinylester or epoxy are also used. The glass can be in the form of a chopped strand mat (CSM) or a woven fabric.
As with many other composite materials (such as reinforced concrete), the two materials act together, each overcoming the deficits of the other. Whereas the plastic resins are strong in compressive loading and relatively weak in tensile strength, the glass fibers are very strong in tension but have no strength against compression. By combining the two materials, GRP becomes a material that resists both compressive and tensile forces well. The two materials may be used uniformly or the glass may be specifically placed in those portions of the structure that will experience tensile loads.
Uses
Uses for regular fiberglass include mats, thermal insulation, electrical insulation, reinforcement of various materials, tent poles, sound absorption, heat- and corrosion-resistant fabrics, high-strength fabrics, pole vault poles, arrows, bows and crossbows, translucent roofing panels, automobile bodies and boat hulls. It has been used for medical purposes in casts. Fibreglass is extensively used for making FRP tanks and vessels.
See also
 |
Look up fiberglass in Wiktionary, the free dictionary. |
- Glass microsphere
- Building insulation
- Fiberglass molding
- Composite materials
- Physics of glass
- Glass transition
- Filament tape
- Optical fiber
- Basalt fiber
- Carbon fiber
- Glass wool
- Gelcoat
- BS4994
Notes and references
- ^ a b Loewenstein, K.L. (1973). The Manufacturing Technology of Continuous Glass Fibers. New York: Elsevier Scientific. pp. 2–94. ISBN 0-444-41109-7.
- ^ a b c Gupta, V.B.; V.K. Kothari (1997). Manufactured Fibre Technology. London: Chapman and Hall. pp. 544–546. ISBN 0-412-54030-4.
- ^ a b c Volf, Milos B. (1990). Technical Approach to Glass. New York: Elsevier. ISBN 0-444-98805-X.
- ^ a b Lubin, George (Ed.) (1975). Handbook of Fiberglass and Advanced Plastic Composites. Huntingdon NY: Robert E. Krieger.
- ^ Frank P. Incropera; David P. De Witt (1990). Fundamentals of Heat and Mass Transfer (3rd ed.). John Wiley & Sons. pp. A11. ISBN 0-471-51729-1.
- ^ KH Hillermeier, Melliand Textilberichte 1/1969, Dortmund-Mengede, page 26–28, "Glass fiber—its properties related to the filament fiber diameter".
External links
- Fiberglass wiki
- Fibreglass Flat Roof
- Fiberglass and health
- Fiberglass Wall Reinforcement Mesh
- International Geosynthetics Society, information on geotextiles and geosynthetics in general.
- Glassfiber Mat for Roofing System
This entry is from Wikipedia, the leading user-contributed encyclopedia. It may not have been reviewed by professional editors (see full disclaimer)
| Translations: Fibreglass |
Français (French)
n. - fibre de verre
Deutsch (German)
n. - Glasfaser
Ελληνική (Greek)
n. - φάιμπεργκλας, υαλοβάμβακας
Italiano (Italian)
fibra di vetro
Português (Portuguese)
n. - fibra (f) de vidro
Русский (Russian)
фиберглас, стеклопластик
Español (Spanish)
n. - fibra de vidrio
Svenska (Swedish)
n. - glasfiber
中文（简体）(Chinese (Simplified))
玻璃纤维, 玻璃棉
中文（繁體）(Chinese (Traditional))
n. - 玻璃纖維, 玻璃棉
עברית (Hebrew)
n. - לוח עשוי מסיבי זכוכית שזורים, סיבי זכוכית, פיברגלס, פלסטיק מחוזק ע"י סיבי זכוכית
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 | Dictionary. The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2007. Published by Houghton Mifflin Company. All rights reserved. Read more |
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