The count of a yarn a numerical expression which defines its fineness.When a engineer requires the fineness of wire ,he consults a Table of standard wire gauge values.For instance in the imperial standard wire gauge values.For instant in the imperial standard wire Gauge table we find that a wire gauge number of 10 corresponded to diameter of 0.128 in.
Alternatively,by measurement of the wire diameter by a micrometer,the corresponding gauge number can be read from the table.Measurement of the diameter of yarn poses rather s different problem.Spun yarns are only roughly circular in -cross-section and irregularity in thickness is unavoidable.Filament yarns with only a small amount of twist in them are referred to as flat yarns possibly because they flatten so easily when in contact with other more solid bodies.Since most yarns are relatively soft and compressible,the use a micrometer for diameter measurement is ruled out.Optical methods can be used one method being described .A magnified silhouette of the yarn is projected on the screen which has a scal graduated in thousands of yarns inch.The object of this testis not a determined in thousand of yarn count inch.
Alternatively,by measurement of the wire diameter by a micrometer,the corresponding gauge number can be read from the table.Measurement of the diameter of yarn poses rather s different problem.Spun yarns are only roughly circular in -cross-section and irregularity in thickness is unavoidable.Filament yarns with only a small amount of twist in them are referred to as flat yarns possibly because they flatten so easily when in contact with other more solid bodies.Since most yarns are relatively soft and compressible,the use a micrometer for diameter measurement is ruled out.Optical methods can be used one method being described .A magnified silhouette of the yarn is projected on the screen which has a scal graduated in thousands of yarns inch.The object of this testis not a determined in thousand of yarn count inch. One special Section of the textile industry,The cordage and rope making trade,use a counting system related to the cross-section area of the yarn: The count of the yarn is the number of such yarns which are required to from one strand of a three-strand 3 in circumference rope.This is an unusual approach used for a particular job and is not met with in the normal run of thing.
Direct And Indirect System of yarn Numbering:
A definition of yarn above contain the phrases 'mass per unit length 'and 'length per unit mass' indicating that two basic principal are employed.
Direct System In a direct system yarn counting system the yarn number or count is the weight of a unit length of yarn.The units of weight and length very from trade to trade and district to district, a state of affairs which results in a multiplicity of counting systems.This will be looked into shortly but for the moment we will consider a general formula which applies to all direct systems.
Let N = The yarn Number or count.
W = The weight of the sample at the official regain in the units of the system.
L = The length of the sample ,and
l = The unit of length of the system.
Example.If asking of 100 m of filament viscose yarn weight 1.67g Calculate its denier.
In the denier system the weight unit is the gram and the 'Unit of length' is 9000m.The denier of yarn is the weight in gram of 9000 m.Thus W=1.67g, L=100m, and l=9000m.There fore
Indirect System:
In an indirect system the yarn number or count is the number of "Units of length" per "Unit of weight".Here again there are various units of length and weight and numerous systems.Generalizing:
Let N = The yarn Number or count.W = The weight of the sample at the official regain in the units of the system.
L = The length of the sample ,and
l = The unit of length of the system.
Example:A lea (120 yd) of cotton yarn weight 25 gr, calculate its count in the cotton system.
In this case the " unit of length is the hank ,840 yd, and the "unit of weight" is 1 lb there are 7000 gr.Hence L = 120 yd, l = 840 yd ,W = 25 / 7000 lb, and w = 1 lb
Counting System:
Table gives the value of the unit of length and weight used in some direct and in direct system of yarn numbering- a curious Table it look,too!.The name of of some will suggest to the reader that one of the reasons for this diversity is geographical.The textile industry grew up in different localities and each chose its own systems to suit local condition.Conversion from one system to another system is achieved by conversion factors and constant.Where a direct to a direct system,or an indirect to an indirect system is concerned, a multiplying conversion factors is used.
Direct System
| System | Unit Of Mass | Unit of length |
|---|---|---|
| Tex | Gram | Killometer |
| Denier | Gram | 9000 meters |
| Linen (dry-spun) ,Hemp,Jute, | Pound | 14,400 yards |
| Jute | Dram | 1000 meters |
| Woollen (Aberdeen) | Pound | 14,400 yards |
| Woollen (American grain) | Grain | 20 yards |
Indirect System
| System | Unit Of Length | Unit of Mass |
|---|---|---|
| Asbestoes ( American) | 100 yards (Cut) | Poun |
| Asbestoes ( British) | 50 yards | Pound |
| Cotton bump yarn | 840 yards | Ounce |
| Cotton (British) | 840 yards (Hank) | Pound |
| Cotton (American) | 1000 meters | 0.5 killograme |
| Cotton (Continental) | 100 yards | Pound |
| Glassb (U S A and U K) | 300 yards (Lea) | Pound |
| Linen (Wet- spun) | Killometer | Killograme |
| Metric | 840 yards (Hank) | Pound |
| Spun Silk | 11,520 yards(spyndle) | 24 Pound |
| Woollen (American cut) | 300 yards (cut) | Pound |
| Woollen (American run) | 100 yards | Ounce |
| Woollen (Dewsbury) | 100 yards | Ounce |
| Woollen (Galashiels) | 300 yards (cut) | 24 Ounce |
| Woollen (Hawick) | 300 yards (cut) | 26 Ounce |
| Woollen (West of England) | 300 yards (cut) | Pound |
| Woollen (Yorkshire) | 320 yards (snap) | Pound |
| Woollen (Yorkshire) | 326 yards (skein) | Dram |
| Worsted | 560 yard (Hank) | Pound |
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