Yarn Count Calculation

Dr. Jimmy Lam Institute of Textiles & Clothing The Hong Kong Polytechnic University

Outlines

• What is yarn count?

• Direct system and indirect system • Single yarn and ply yarn calculation • Metric system, Tex system and Cotton system conversion • Examples

Formula

• Tex = mass (g)/ length (m) X 1000 • Conversion from Tex to other systems 1. Tex X Count =590.5 (Cotton System) 2. Tex X 9 = Denier (Filament System) 3. Tex X Metric Count =1000 (Knitwear system)

Yarn Count

• Two Systems, namely Indirect System and Direct System • In sweater calculation, we normally converted both into Metric system (Nm)

• • • • •

Indirect System

Normally uses for cotton yarn and most of cotton yarn) Symbol: NeC or ECC or ‘s Definition: Number of unit length per unit mass (variable length, constant weight) yarn.

yarn.

Indirect System

• Cotton Count (NeC) = Length (yd) x 840 /weight (pound) • Metric system (Nm)=Length (km) per weight (1 kg) • Conversion 1 Nm =NeC X 1.693

Indirect System Example

• A skein of 26,880 yards weight 1 pound, calculate its English count and Metric equivalent.

• Answer: • Cotton Count=26,880/840 =32NeC • Metric (Nm) =32 x 1.693 =54Nm

Direct System

• • • • Normally uses for continuous filament yarns such as viscose rayon, polyester, etc.

Definition: Number of mass per unit length (Variable weight and constant length) The higher the count number, the coarser the yarn.

The lower the count number, the finer the yarn.

Direct System

• • • • • • • 9000 Tex = weight (g) per length (m) x 1000 Conversion to Metric System (Nm) Nm=9000 /denier (Td) Nm=1000/Tex (Tt) Conversion between Tex and Denier Tex=Denier/9

Direct System Example

• A skein of 300 meters of filaments viscose rayon yarn weights 10 grams, calculate its denier and metric equivalent.

• Answer: • Denier = 10 /300 x 9000 = 300Td • Metric (Nm) = 9000/300 =30Nm

More Example

• • • • • Ex1: 20/2 NeC 55% acrylic, 45% cotton yarn Metric System = 2/(20 x 1.693) =2/34Nm =17 Nm Ex2: 11/2 NeC 55% ramie, 45% cotton yarn Metric System= 2/(11 x.1693) =2/18.6Nm

Resultant Count

– Yarn produced by the combination of two or more single yarns is used in many textile structures in order to achieve effects which may not be readily obtained by single yarn.

– In an indirect system, the resultant count is equal to the sum of the reciprocals of the component yarns.

– 1/N = 1/N 1 + 1/N 2 where N is resultant count and N 1 and N 2 are component yarns

Resultant Count

– Answer:

Example

– A two fold yarn (ie yarn made by twisting two single yarn together) is found to have one 300 Td 100% viscose rayon yarn and one 20/1 NeC 100% cotton yarn. Calculate the equivalent single count in metric system.

– Metric (Nm) for rayon =9000/300=30Nm – Metric (Nm) for cotton= 20 x 1.693 =33.87Nm

– Resultant Count 1/N = 1/30 + 1/33.87

– =1/15.9Nm

Yarn component calculation

– A sweater is knitted with two different yarns. One end is 32/2 NeC 100% cotton yarn and the other end is of plated 84 Denier (Td) 85% nylon, 15% lycra yarn. Calculate: – A) The resultant count of the component yarn; – B) The percentage by weight of various yarn used; – C) The fibre content of the sweater

Yarn component calculation Answer

– A) Resultant Count: • Cotton =32/2 x 1.693 =17 x 1.693=27Nm • • • Nylon and lycra=9000/84=107Nm Resultant Count 1/N =1/27 + 1/107 =1/21.6Nm

– B) Percentage by weight of two components in every km: • • • • • Cotton=1/27Nm =1/27kg =0.037kg

Nylon and lycra =1/107Nm =1/107kg =0.009kg

Total weight of two components:0.037+0.009 =0.046kg

Percentage of Cotton: 0.037/0.046x100% =80% Percentage of Nylon/lcyra =0.009/0.046x100%= 20%

Yarn component calculation Answer

– c) Fibre composition of the component yarns: • Cotton =80% x 100%= 80% • Nylon = 20% x 85% = 17% • Lycra =20% x 15% =3% • The fibre content of the sweater is: • 80% cotton, 17% nylon and 3% lycra