Wednesday, 22 July 2009

Terry Towel Calculations-2



Continued from Terry Towel Calculations-1

How to Determine the Weight of Pile Warp in Terry Towel

Weight of Pile Warp = weight of pile warp in pile part + that in plain part + that in fringe

a. Weight of pile warp in pile part ( Pile ratio: 52:10)
=( Length of pile part x number of pile threads x pile length x yarn count in tex) / (100 x 1000)
= (102 x 576 x 52 x 30 x 2)/(100 x 1000)
= 183.31 g

b. Weight of Pile warp in Plain Part
=( Length of plain fabric x number of pile threads x crimp factor x yarn count)/ (100 x 1000)
= (4 x 576 x 1.08 x 30 x 2)/(100 x 1000)
= 1.49 g

c. Weight of Pile warp in fringe ( No crimp , no loop )
= (fringe length x number of pile threads x yarn count)/(100 x 1000)
= (2 x 576 x 30 x 2)/(100 x 1000)
= 0.69 g
Weight of pile warp = 183.31+ 1.49 + 0.69 = 185.49

How to Determine the Weight of Weft in Terry Towel

Weight of Weft Yarn

= (Total no of weft threads x reed width x yarn count)/(100 x 1000)
(Reed width is equal to the length of one weft yarn)
= (106 x 20 x 58.4 x 34)/(100 x 1000)
= 42.09 g

Tuesday, 21 July 2009

Terry Towel Calculations-1



Terry Towel Calculations – 1

Calculating the Weight of Ground Warp in a Terry Towel

A terry towel is different from an ordinary woven fabric because it has a looped surface. These loops are responsible for the towel’s softness, bulk, absorbency and characteristic hand feel. Unlike a simple plain woven cloth, a terry towel normally uses two warp systems and one weft system. These are the ground warp, pile warp and weft.

The ground warp forms the foundation of the towel. It gives strength and stability to the fabric. The pile warp forms the loops on the surface. The weft binds the warp systems together and helps create the final towel structure. In this article, we shall calculate only the weight of the ground warp used in one towel. The pile warp and weft calculations can be taken separately.

Table of Contents

  1. Understanding the Terry Towel Structure
  2. Given Data
  3. Understanding Tex
  4. Why Ground Warp Is Calculated in Two Parts
  5. Formula for Ground Warp in Grey Fabric
  6. Calculation of Ground Warp in Grey Fabric
  7. Why Warp Crimp Is Important
  8. Formula for Ground Warp in Fringe
  9. Calculation of Ground Warp in Fringe
  10. Total Ground Warp Weight
  11. Why the Ground Warp Weight May Look Small
  12. Practical Notes for Textile Calculations
  13. Key Learning
  14. Related Reading
  15. Sources
  16. General Disclaimer

1. Understanding the Terry Towel Structure

In a terry towel, the pile loops are not accidental. They are deliberately formed by controlling the movement and tension of the pile warp during weaving. The pile warp is usually kept under lower tension than the ground warp, so that it can be pulled forward and formed into loops. The ground warp remains more tightly controlled and works as the structural base of the towel.

This is why terry towel weight calculation is not done exactly like a simple flat fabric calculation. We have to treat each yarn system according to its function in the fabric. The ground warp, pile warp and weft do not consume yarn in the same way. Their yarn counts, lengths, crimp values and structural roles may be different.

Terry towel structure showing ground warp pile warp and weft
Visual 1: Basic terry towel structure showing ground warp, pile warp and weft.

2. Given Data

Let us assume the following construction details for the towel. These values are used to explain the method of calculation. In practical mill work, the values should be taken from actual fabric construction, loom settings, yarn count records and production data.

Parameter Value
Length of grey towel 106 cm
Number of ground warp ends 694
Ground warp count \(25 \text{ tex} \times 2\)
Warp crimp 8%
Warp crimp factor 1.08
Fringe length 2 cm

The ground warp count is given as \(25 \text{ tex} \times 2\). This means that the yarn is a two-ply yarn. Each ply is 25 tex, so the effective yarn count for calculation is:

\[ 25 \times 2 = 50 \text{ tex} \]

3. Understanding Tex

Tex is a direct yarn count system. It tells us how many grams are present in 1000 metres of yarn. In direct count systems, a higher tex value means a heavier or coarser yarn, while a lower tex value means a finer yarn.

\[ \text{Tex} = \frac{\text{Weight in grams}}{1000 \text{ metres}} \]

So, if a yarn is 50 tex, it means that 1000 metres of that yarn weighs 50 grams. This makes tex very useful for calculating yarn weight when the length of yarn is known.

Practical point: Whenever tex is used, the length must ultimately be converted into metres. Since towel dimensions are often written in centimetres, the centimetre-to-metre conversion must be handled carefully.

4. Why Ground Warp Is Calculated in Two Parts

The ground warp is present in two places. It is present in the main grey fabric body of the towel, and it is also present in the fringe portion. These two portions are treated separately because the yarn behaviour is different in both areas.

In the grey fabric body, the ground warp interlaces with the weft. Because of this interlacement, the yarn does not remain perfectly straight. It follows a slightly wavy path. This extra length is called warp crimp or warp take-up.

In the fringe portion, the yarn is generally considered to be straight and loose. Therefore, warp crimp is usually not added to the fringe calculation in a basic estimate.

\[ \text{Total ground warp weight} = \text{Ground warp in grey fabric} + \text{Ground warp in fringe} \]

5. Formula for Ground Warp in Grey Fabric

The formula for calculating the ground warp weight in the grey fabric body is:

\[ \text{Ground warp weight in grey fabric} = \frac{ \text{Grey length} \times \text{Warp crimp factor} \times \text{Number of ground ends} \times \text{Yarn tex} }{ 100 \times 1000 } \]

The denominator \(100 \times 1000\) is used for unit conversion. The fabric length is given in centimetres, while tex is based on metres. Since \(100 \text{ cm} = 1 \text{ metre}\), and tex is based on \(1000 \text{ metres}\), the conversion factor becomes:

\[ 100 \times 1000 = 100000 \]

Ground warp calculation flow showing length crimp ends tex and unit conversion
Visual 2: Ground warp calculation flow from construction data to yarn weight.

6. Calculation of Ground Warp in Grey Fabric

Substituting the values:

\[ \text{Ground warp weight} = \frac{ 106 \times 1.08 \times 694 \times 25 \times 2 }{ 100 \times 1000 } \]

Since \(25 \times 2 = 50\), we can write:

\[ \text{Ground warp weight} = \frac{ 106 \times 1.08 \times 694 \times 50 }{ 100000 } \]

\[ = 39.72 \text{ grams approximately} \]

Therefore:

\[ \boxed{\text{Weight of ground warp in grey fabric} = 39.72 \text{ g}} \]

7. Why Warp Crimp Is Important

Warp crimp is the extra yarn length required because of interlacement. In a woven fabric, warp yarns pass over and under the weft yarns. This makes their actual path longer than the straight fabric length. Therefore, if we calculate warp consumption only from the straight fabric length, we may underestimate the yarn actually required.

If the fabric length is 100 cm and the warp crimp is 8%, the actual yarn length consumed is:

\[ 100 \times 1.08 = 108 \text{ cm} \]

So an 8% crimp means that for every 100 cm of fabric length, 108 cm of warp yarn is required. In this example, a crimp factor of 1.08 has been used:

\[ 1 + \frac{8}{100} = 1.08 \]

In actual production, warp crimp may vary depending on yarn tension, weave structure, reed setting, picks per cm, finishing shrinkage and loom conditions. Therefore, crimp should ideally be taken from mill records or measured from actual fabric samples.

8. Formula for Ground Warp in Fringe

The fringe length is calculated separately. The formula is:

\[ \text{Ground warp weight in fringe} = \frac{ \text{Fringe length} \times \text{Number of ground ends} \times \text{Yarn tex} }{ 100 \times 1000 } \]

In this basic calculation, crimp is not added to the fringe because the fringe yarn is not interlaced like the main fabric body. However, for a detailed production costing, fringe trimming, knotting, twisting and wastage may also have to be considered.

9. Calculation of Ground Warp in Fringe

Substituting the values:

\[ \text{Ground warp weight in fringe} = \frac{ 2 \times 694 \times 25 \times 2 }{ 100 \times 1000 } \]

Since \(25 \times 2 = 50\):

\[ \text{Ground warp weight in fringe} = \frac{ 2 \times 694 \times 50 }{ 100000 } \]

\[ = 0.69 \text{ grams approximately} \]

Therefore:

\[ \boxed{\text{Weight of ground warp in fringe} = 0.69 \text{ g}} \]

10. Total Ground Warp Weight

Now we add both parts:

\[ \text{Total ground warp weight} = \text{Ground warp in grey fabric} + \text{Ground warp in fringe} \]

\[ = 39.72 + 0.69 \]

\[ = 40.41 \text{ grams approximately} \]

Therefore:

\[ \boxed{\text{Total ground warp weight} = 40.41 \text{ g}} \]

11. Why the Ground Warp Weight May Look Small

At first glance, the ground warp weight may appear small. However, this is understandable in terry towel construction. A terry towel is not a flat fabric where the ground warp, weft and total fabric weight are closely balanced. In a terry towel, the pile warp contributes a major share of the final weight because the pile warp forms the loops.

The ground warp is mainly a foundation system. Its purpose is to hold the fabric together and provide dimensional stability. It is not expected to contribute the largest portion of the towel weight. The pile warp, because of its loop formation and pile ratio, normally consumes much more yarn than the ground warp.

Comparison of yarn weight contribution in terry towel ground warp pile warp and weft
Visual 3: Conceptual comparison of ground warp, pile warp and weft contribution in a terry towel.

12. Practical Notes for Textile Calculations

This calculation is a basic yarn consumption estimate. It is useful for understanding how ground warp weight is calculated, but actual mill calculations may require additional allowances. In production, theoretical yarn consumption and practical yarn requirement are not always the same.

Factor Why it matters
Actual warp crimp Changes the real yarn length consumed in the fabric body.
Loom waste Extra yarn is required during weaving, tying, starting and ending.
Beam gaiting waste Warp preparation and loom setting may consume additional yarn.
Fringe trimming The final towel may lose some yarn during trimming or finishing.
Sizing material Sizing may increase grey fabric weight before desizing or washing.
Moisture regain Measured yarn and fabric weight may vary with atmospheric moisture.
Yarn count variation Actual yarn may differ slightly from the nominal tex value.
Finishing shrinkage Final dimensions and GSM may change after washing and finishing.

Therefore, for production costing, this theoretical value should be adjusted using mill experience and actual fabric measurements. The formula gives the logic, but the mill data gives the practical correction.

13. Key Learning

The ground warp weight of a terry towel depends on four main things: the length of the towel, the number of ground warp ends, the yarn count in tex and the warp crimp or take-up. The basic logic is simple:

\[ \text{Yarn weight} = \frac{ \text{Yarn length} \times \text{Number of yarns} \times \text{Tex} }{ 100 \times 1000 } \]

The most important point is to handle the units carefully. Since tex is based on grams per 1000 metres and towel length is often given in centimetres, the conversion factor must be applied properly. A calculation may look simple, but a small unit error can produce a very large difference in yarn consumption and costing.

For a textile student, merchandiser or production planner, this calculation gives a useful foundation for understanding towel costing and yarn consumption. The ground warp is only one part of the towel. To calculate the complete towel weight, one must also calculate the pile warp and weft weights separately.

\[ \text{Total towel weight} = \text{Ground warp weight} + \text{Pile warp weight} + \text{Weft weight} \]

In the next part, we can calculate the pile warp weight, which is usually the most important contributor to the weight, feel, absorbency and bulk of a terry towel.

Sources

  1. Hutex. Terry Towel: Terry Weaving. Available at: https://hutex.co.kr/wp-content/uploads/2023/06/Terry_Towel.pdf
  2. ScienceDirect Topics. Pile Warp - An Overview. Available at: https://www.sciencedirect.com/topics/engineering/pile-warp
  3. Textile School. Terry Towels: Fabrics That Can Absorb Large Amounts of Water. Available at: https://www.textileschool.com/3211/terry-towels-fabrics-that-can-absorb-large-amounts-of-water/
  4. Resil Chemicals. Technical Tuesday: Terry Towel. Available at: https://resiltextiles.com/wp-content/uploads/simple-file-list/Technical-Tuesday/2014/TT-Terry-Towel.pdf
  5. ResearchGate. An Investigation into the Parameters of Terry Fabrics Regarding the Production. Available at: https://www.researchgate.net/publication/293131432_An_investigation_into_the_parameters_of_terry_fabrics_regarding_the_production

General Disclaimer

This article is intended for educational understanding of terry towel yarn consumption calculations. The numerical values used here are illustrative and should not be treated as universal production standards. Actual mill calculations may vary depending on yarn count variation, loom settings, pile ratio, warp and weft crimp, sizing, wastage, finishing shrinkage, moisture regain and the specific construction of the towel.

For commercial costing, production planning or quality control, the calculation should be verified with actual fabric samples, mill records and approved technical specifications.

Loom Temples



Temples

The warp sheet normally contracts from 2 to 15 percent in width from reed to the cloth. This contraction is due to interlacement of warp and weft.

This contraction need to be avoided temporarily because otherwise:

1. There is a possiblity of damage to the warp ends near the selvedge due to abrasion with reed dents.

2. There is a possibility of reed dents getting themselves distorted.

3. There will always be a tension in the beat-up zone.

The temples are used to hold fast the width of the woven cloth as equal to as possible to the width of the warp.

Types of Temples

1. Ring Temples


In ring temples the rings are usually at an angle of 12 deg to 21 deg and the angle reduces in steps of 3 deg towards the centre of the cloth.

As a thumb rule the lenght of the pints should be about one and a half times to two times the cloth thickness. The pins exert their pull on the warp.


Also the greater the tube diameter the greater the wrap of the cloth on the temple tube.

The length of the temple tube depends upon the cloth width. A rule of thumb is one ring for 10 cm fabric.

For delicate cloth, pinned rings are used only in the cloth selvedge zone. The inner rings are substituted by textured surface rubber, plastic or bras rings.


2. Roller Temples


The roller temples usually have two rollers supported at both ends which guide the fabric in the warp directions by means of raised points. The rollers are usually of steel and are covered with rubber or plastics.


Ring and roller temples hold the fabric in the selvedge zones only and stretches the fabric outwards.

These temples have the disadvantage that the pressure of the beat-up of the reed against the fabric is transmitted to the next guiding point of the fabric, which is the breast beam. This point is several inches from the fell of the cloth and therefore extensive tension is required for the beat-up. The tension causes breakages of the warp yarns.

Another disadvantage of this group of temples is the presence of different lengths of the fabric from the fell of the cloth to the breast beam, caused by the looping of the fabric around the temple cylinders. This causes a deformation of the straightness of the weft and therefore of the design. In extreme cases it creates waviness of the selvedges.

3. Full Width Temples

The other group consists of full-width temples.


The full width temples hold the fabric across its full width under uniform tension. The advantages of using full width temples are that weaving can be done at lower warp tension. One more advantage is less stress for the ends, resulting in less ends breakage.There are no temple ring marks. A higher weft density is possible. There is a straight weft insertion over the whole width. Also less maintenance is required.

However the full-width temples cannot avoid a contraction of the fabrics weft wise. By reason of this contraction, the warp ends in the selvedges do not pass at straight angle through the weaving reed. This causes extensive friction between yarn and reed and can lead yarn breakages.

Saturday, 18 July 2009

Denim Silk- Challenges in Production and Marketing



Silk denim, developed in India by CSTRI seems to have a lot of potential. With the market of denim in India growing by leaps and bounds, denim silk will give that niche in the minds of customer that can make a company profitable.

There are however lots of challenges that denim jeans made of silk will face in the market. First there is a problem/question of its production viability. Then there will be a question of its wearing performace.

Then of course care of this fabric will be a major challange. Even if this is overcome, cost will be a deciding factor in this recession hit economy. And of course, there will be always a challenge to fight from the spurious fabrics.

Lets talk about parameters. The warp in silk is made from 20/22 denier 6 and 12 ply organzine twisted(Organzine is a thread made by giving the raw-silk thread a preliminary twist in one direction and then twisting many of these threads together in the opposite direction at the rate of about 4 turns/cm ) mulberry silk fiber or eri silk of 2/60s, 2/80s and 2/120s is used. In weft 6 and 12 ply tram twisted (Tram is made by twisting in only one direction two or more raw-silk threads, with 8 to 12 turns/cm). Mulberry silk and eri silk of 2/60s, 2/80s and 2/12s greige yarn is used. All this is OK, the only concern is the avaliability of these fibers. It is then made on rapier looms with 44" width and 3/1 twill weighing 100-300 gsm. The only questions are the production challenges while handling such delicate fibers.

Functionally, twill weaves in silk are prone to slippage of yarn, particulary if two different fibers are used in warp and weft.which might affect the tear strength and seam slippage.

Also the faded look of denim comes from Indigo dye, which is a vat dye, and which is faded differentially as the denim is washed. In Silk Denim, Indigo colored acid dyes are used, which dont fade at all. This will maintain the consistency of shade for years, but surely will take away the joy of fading that is obtained with cotton denim.

Then of course there are issues for the care and maintainenace of these fabrics. These must be dry cleaned and taken care of properly. Also eri silk denim will behave like wool and more suitable in winter.

The biggest issue of all is the cost. Due to limited supply, the quality silk denim would be much much costlier than the normal indigo cotton denim.

Thus all the discussion above will point out to the a very specific market for silk denims. Target audience would be upper class young females in the age group of 25-40. It would be better if the bottoms were to sold with the matching printed or plain silk tops. It would be further beneficial for a marketer if the word 'denim' is taken out of this fabric, as customer will erroneously compare the properties of indigo denim with this fabric. Some surface emballishments can be done like printing or embroidery on these garments.

http://www.galenfrysinger.com/shanghai_china_silk.htm
http://www.fibre2fashion.com/industry-article/11/1014/silk-denim1.asp

And then have a look at this.

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