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Friday, September 10, 2010

Fibre Forms and Architecture

a. strand - a compactly associated bundle of filaments. Strands are rarely
seen commercially and are usually twisted together to give yarns.

b. yarns - a closely associated bundle of twisted filaments or strands with
the same filament diameter each between 4-13 mm.
Yarns have varying weights described by their ‘tex’ (weight in grammes
of 1000 linear metres) or denier (weight in lbs of 10,000 yards).
Typical tex range usually being between 5 and 400.

c. rovings - a loosely associated bundle of untwisted filaments or strands.
The same each filament diameter in a roving, usually between 13-24mm.
Have varying weights, i.e. tex range is usually between 300 and 4800.
Two basic types of roving:
Direct roving - filaments are gathered together directly after melting.
Assembled roving - several strands be brought together separately after
manufacture, and usually have smaller filament diameters for better
wet-out and mechanical properties.

d. Chopped strands – continous strands which are chopped into into
various lengths, i.e. 3, 6, 9, 12, 25, 50 mm.
Commonly used in moulding compounds (BMC/DMC) or reinforcing
sharp radii, etc.

e. Chopped strand mat (CSM) - a principal form of glass fibres for fibreglass.
Chopped filament strands of 50 mm length, bonded by suitable binder
which are then pressed to form a mat and wound into rolls.
Typical CSM densities between 225 to 900 gram/m2.
Due to random orientation, common glass to resin ratio range between
1:2 to 1:2.5 by weight.

f. Continous filament mat (CFM) - a continuous glass strand of swirl mat.
Designed for press moulding (cold/hot) and RTM.
Random orientation of continuous multi-filament with low binder content
Allows exceptional wetting compared to CSM, considerable stretch,
and minimises tailoring.

g. Woven roving (WR) – glass roving which are woven to form cloth type
with densities range between 150 to 900 gram/m2.
Glass to resin ratio for WR is usually taken as 1:1, i.e. higher fibre content.
Disadvantages: difficult to cut, difficult to handle (when cut), and more
difficult to mould than CSM.
Typical construction would be WR and CSM laid-up alternately.

h. Woven fabric (cloth) – a woven product of textile yarns with various
weaving styles (plain, twill, harness satin, etc.) and densities range
between 90 to 300 gram/m2.
More expensive and use for high performance applications such as
aircrafts and electrical.
i. Surfacing mat (tissue) – use for backing gelcoat and final decorative layer.
Designed for press moulding (cold/hot) and RTM.

j. Special products/hybrids – combination of various types and forms of
glass to meet individual needs, processes and end-product performance.