Editing Glass fiber (section)

==Manufacturing processes==

=== Melting ===
There are two main types of glass fiber manufacture and two main types of glass fiber product. First, fiber is made either from a direct melt process or a [[Marbles|marble]] remelt process. Both start with the raw materials in solid form. The materials are mixed together and melted in a [[Metallurgical furnace|furnace]]. Then, for the marble process, the molten material is [[Shear (fluid)|sheared]] and rolled into marbles which are cooled and packaged. The marbles are taken to the fiber manufacturing facility where they are inserted into a can and remelted. The molten glass is extruded to the [[Threaded bushing|bushing]] to be formed into fiber. In the direct melt process, the molten glass in the furnace goes directly to the bushing for formation.<ref name="Lubin" />

=== Formation ===
The bushing plate is the most important part of the machinery for making the fiber. This is a small metal furnace containing [[nozzle]]s for the fiber to be formed through. It is almost always made of [[platinum]] alloyed with [[rhodium]] for durability. Platinum is used because the glass melt has a natural affinity for [[wetting]] it. When bushings were first used they were pure platinum, and the glass wetted the bushing so easily that it ran under the plate after exiting the nozzle and accumulated on the underside. Also, due to its cost and the tendency to wear, the platinum was alloyed with rhodium. In the direct melt process, the bushing serves as a collector for the molten glass. It is heated slightly to keep the glass at the correct temperature for fiber formation. In the marble melt process, the bushing acts more like a furnace as it melts more of the material.<ref>{{cite book|last = Loewenstein|first = K.L.|year = 1973|title = The Manufacturing Technology of Continuous Glass Fibers|publisher = Elsevier Scientific|location = New York|page = 91|isbn =978-0-444-41109-9}}</ref>

Bushings are the major expense in fiber glass production. The nozzle design is also critical. The number of nozzles ranges from 200 to 4000 in multiples of 200. The important part of the nozzle in continuous filament manufacture is the thickness of its walls in the exit region. It was found that inserting a [[counterbore]] here reduced wetting. Today, the nozzles are designed to have a minimum thickness at the exit. As glass flows through the nozzle, it forms a drop which is suspended from the end. As it falls, it leaves a thread attached by the [[Meniscus (optics)|meniscus]] to the nozzle as long as the viscosity is in the correct range for fiber formation. The smaller the annular ring of the nozzle and the thinner the wall at exit, the faster the drop will form and fall away, and the lower its tendency to wet the vertical part of the nozzle.<ref>{{cite book|last = Loewenstein|first = K.L.|year = 1973|title = The Manufacturing Technology of Continuous Glass Fibers|publisher = Elsevier Scientific|location = New York|page=94|isbn =978-0-444-41109-9}}</ref> The surface tension of the glass is what influences the formation of the meniscus. For E-glass it should be around 400&nbsp;mN/m.<ref name="Volf" />

The attenuation (drawing) speed is important in the nozzle design. Although slowing this speed down can make coarser fiber, it is uneconomic to run at speeds for which the nozzles were not designed.<ref name="Lowenstein"/>

=== Continuous filament process ===
In the continuous filament process, after the fiber is drawn, a [[Sizing|size]] is applied. This size helps protect the fiber as it is wound onto a bobbin. The particular size applied relates to end-use. While some sizes are processing aids, others make the fiber have an affinity for a certain resin, if the fiber is to be used in a composite.<ref name="Lubin" /> Size is usually added at 0.5–2.0% by weight. Winding then takes place at around 1&nbsp;km/min.<ref name="Gupta" />

=== Staple fiber process ===
For staple fiber production, there are a number of ways to manufacture the fiber. The glass can be blown or blasted with heat or steam after exiting the formation machine. Usually these fibers are made into some sort of mat. The most common process used is the rotary process. Here, the glass enters a rotating spinner, and due to [[centrifugal force]] is thrown out horizontally. The air jets push it down vertically, and binder is applied. Then the mat is vacuumed to a screen and the binder is cured in the oven.<ref name = "Mohr 13">{{cite book  | last = Mohr  | first = J.G.  |author2=W.P. Rowe  | year = 1978  | title = Fiberglass  | publisher = Van Nostrand Reindhold  | location = Atlanta  | page = 13  | isbn =978-0-442-25447-6}}</ref>