Glass fiber filaments are obtained by high-temperature melting of inorganic materials which are drawn through a platinum-rhodium bushing, and then rapidly cooled. Glass yarn is formed by combining more single filaments, between 4 to 13 microns depending on yarn count, in a continuous strand.
Different glass yarn types are obtained according to the materials used:
Glass Yarn Nomenclature
Each of the two most used systems (SI system and US system) has its own Yarn Nomenclature as follows:
Example: E C G 75 1/2 2.8 S
E = electrical glass
C = continuous filament
G = average filament diameter
75 = 7,500 yards/lb. nominal bare glass in basic strand
1/2 = one ply of 2-strand construction
2.8 = the number of turns per inch (TPI) in the twist of the final yarn
S = the direction of the twist
Example: E C 9 68 1×2 112 S
E = electrical glass
C = continuous filament
9 = 9 micrometers
68 = 68 grams per 1,000 meters of yarn
1×2 = one ply of 2-strand construction (total 2 basic strands)
112 = the number of turns per meter (TPM) in the twist of the final yarn
S = the direction of the twist