How to Calculate Maximum EPI and PPI for a Fabric with Given Count

A Reader has asked me this question:

“ I want to know how to calculate max EPI and PPI of the given count. For Example, if we take 50s pv warp X 150 D  100% polyester weft, what will the max EPI and PPI if we weave it for plain, 2/2 twill,and satin.”

Here Mr. Ashenhurst can rescue us. The following method is based on his book “Textile Calculation and Structure of Fabrics”. Here the assumption is there is only one count of thread in both warp and weft. If there are two different counts of warp and wefts, threads per inch should be found out for both of them and then suitably adjusted.

The General formula to calculate Maximum EPI and PPI for a Given count of Warp and Weft

Now in a plain weave in a repeat there are 2 threads and 2 intersections. For 2/2 Twill in one repeat of 4 threads there will be 4 threads and 2 intersections.

Also as a rule please remember that 40s count yarn diameter is 1/165 of an inch.

To convert it to the yarn diameter of 50s warp we use the following formula

Which means for 50s PV Warp the diameter will be

Thus the Maximum Threads per inch for a plain weave will be 184 as this will be the diameter of the Yarn.

For 2/2 Twill be they will be ( From the Formula above)

Which means x will be equal to 122 threads per inch

Similarly for Satin weave one can find out the maximum ends and picks per inch

Please remember however that this is theoretical construct. Actual threads per inch are generally less than that.

To Calculate the Cotton Equivalent of 150 D, We use the formulaà count= 5315/denier, Which means it is equal to 35.43 or 35 count.

The Diameter for 35 count yarn will be ( Using the formula above) = 154.34 th of an inch

Then you can use the same equation to calculate the Maximum EPI and PPI

In these examples there is no allowance for bending, shrinkage or compression, the threads should be reduced or increased proportionately in case the fabric is subjected to bending, shrinkage or compression.

Indian Traditional Textiles- The document

traditionaltextiles.pdf

Sindhi Taropa Style of Kathiawar

The Sindhi Taropa denotes the interlacing stich embroidery-- the basic structure which is first built up with the use of long thread stitches into the surface and entire structure being built up thereafter by looping these threads, the overall effect produced is geometrical; floral patterns or figures, whatever is worked out through this type of stitch become-somewhat stylized. Practically the stitch is used as a means of achieving only an impression of the figure or motif which is aimed at.

How to calculate the weight of Fabric

How to Calculate Warp and Weft Yarn Required for a Standard 100m of Fabric

Here is one Query:

"I run a small business of supplying 100% cotton fabric to exporters . As you are aware the cotton yarn prices are on the rise on a daily basis, and the rates that I get from vendors is totally disproportionate to the rise in price. In this regard I request you to kindly teach me a formula to calculate the wrap and weft yarn required for a standard 100 meters of fabric in required widths of 47" and 60". Please suggest the formula in cotton counts."

We need a few things to start Calculating the weight

1.      Yarn count of Warp and Weft

2.      Ends per inch ( Reed) and Picks per inch ( Picks) of the fabric

3.      Width of the Fabric

I am assuming the following ( If you don’t understand, please don’t bother about this, you will be able to calculate the weight of the yarn with certain accuracy) :

1.      Warp Crimp 10%

2.      Weft Crimp 3%

Weight of one meter of Fabric in Grams =((Ends per Inch x Width in Inch x 1.10)/(Warp Count x 840) + (Picks per Inch x Width in Inch x 1.03)/(Weft Count x 840)) x (1.09x 1000/2.2)

Take Ends/Inch and Multiply by Width in inches and 1.10. Divide this quantity by Warp count multiplied by 840. This will give you weight of Warp in pounds of one yard (a). To find the weight of the warp in one meter of fabric in grams multiply (a) by 1.09 and 1000 and divide by 2.2.

Take Picks per inch Multiply by width in inches and 1.03. Divide this quantity by Weft Count multiplied by 840. This will give you Weight of weft in one yard of fabric (b). To find the weight of the weft in one meter of fabric in grams multiply (b) by 1.09 and 1000 and divide by 2.2

Now Add (a) and (b) to get the total weight of warp and weft in one yard of fabric. Let us say this value is (c). Now Multiply (c) by 1.09 and 1000 and divide it by 2.2 to get the weight of one meter of fabric in grams.  Multiply it by 100 to get the weight of 100 meters of fabric in Grams. 

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