Warp Knitting | Calculation of Yarn run-in (mm/rack)

The relationships between fabric parameters and yarn run-in (yarn consumption) is an extremely important factor for production planning.This data allows the knitter to estimate his yarn requirements,predict  his production rate.
The values needed to determine the yarn run-in :
Lapping,Gauge  E (needles/inch) ,course per cm (CPC),needle thickness  (d).
Calculation :

Head of the loop = πd /2.2	d = needle thickness
Legs of the loop = 2 x S	S = 10 mm : course per cm (cpc)
a =  number of needle loops b =  number of needle gaps crossed by the sinker loop c =  number of sinker loops in the same wale	T = 25,4 mm : E (gauge)

Yarn run-in (mm/rack) *= 480 [a ( πd /2.2  + 2S) +bT + cT ]
notice : * The calculated values are as approximate values
Example 1 :

E = 28 CPC = 20

d = 0,5 mm Lapping =  1 0 / 1 2 //   | a = 1 | b = 1 | c = 0 (per course).

Yarn run-in (mm/rack) = 480 ( 0,7 mm + 1 mm +0,9 mm) = 1250 mm/rack

Example 2 :

• Yarn run-in (mm/rack) = 480 ( πd /2.2  + 3 S )  notice : * The calculated values are as approximate values
• Yarn run-in (mm/rack) = 480 (0,7 mm + 1,5 mm)
• Yarn run-in (mm/rack) = 1056 mm

Example 3 : 

• Yarn run-in (mm/rack) = 480 [2 ( πd /2.2  + 2S) +bT + cT ]  notice : * The calculated values are as approximate values
• Yarn run-in (mm/rack) = 480 [2 (1,7 mm + 0,9 mm + 0,45 mm) ]
• Yarn run-in (mm/rack) = 480 [ 2 (3,05 mm) ]
• Yarn run-in (mm/rack) = 2928 mm