HVI parameters are used to measure the quality of cotton bales. These parameters are important for grading and sorting. The measurement process is divided into two different stages, which includes:
- First stage of HVI parameters measurement procedure involves taking an initial reading on a sample of raw material using a standardized method developed by HVI.
- Second stage involves repeating this measurement on each sampled bale in order to obtain a final value which represents the overall quality attributes of that particular batch at that point in time
1) Mic – Micronaire
Here are some of the interesting points about Micronaire:
- Micronaire is a measure of the fineness of cotton.
- It can be calculated using the following equation:
M = D/1000, where M is micronaire; D is diameter; and 1000 is an average value for each filament diameter in millimeters.
2) Length(MM) – Staple Length In MM
Length of staple is the length of individual fibers in a cotton bale. It is an indication of the quality of cotton. A long staple has more fiber length than a short one, which means it will be less likely to break when processed into bales or even into yarns.
Longer staples are generally considered better quality because they don’t break easily during processing and have more cotton luster (color). Longer staples also tend to have fewer impurities, so you can expect less shrinkage when you wash them at home with your machine set on a gentle setting as opposed to washing clothes using hot water alone—which can cause shrinkage due to shrinking caused by friction between different surfaces rubbing together while drying out after being washed.
3) STRENGTH(G/Tex) – STRENGTH PARAMETER
Strength is a parameter that measures the tensile strength of the fabric. Strength is measured in g/tex, which is equal to how many grams of force can be applied to a single tex of fabric before it breaks. When you look at your garment’s label, you may see this term and wonder what it means. The answer lies within the HVI and its myriad of parameters!
As seen above, strength = Gms per Tex (or Gm/T)
4) Elasticity % – Elasticity %
Elasticity is a measure of the amount of energy required to stretch a fabric. It is measured in percentage, and it has units of Joules per meter.
The elasticity is calculated using the equation:
- Original length (m) = Length after stretching (m) – Length before stretching (m).
- Extension (m) = Original length * Elasticity %/100%.
5) Unit Weight (G/M2)-Unit Weight
UNIT WEIGHT is the weight of the fabric per unit area. It is expressed in g/m2 and is used to calculate the price of the fabric.
6) Trash %- Trash %
Trash % is a measure of the foreign matter content in a bale. It is measured as a percentage of the weight of the bale, and can be determined by weighing or measuring it with a hydrometer or manometer. If you have access to both types of equipment (hydrometers are used for testing liquids while manometers are used for measuring gases), then you can determine how much trash your product has by using one type at certain intervals throughout its life cycle and comparing them against each other.
Trash % is also important because it determines how much money you lose when selling an HVI product because there’s no way around this rule: if your product has too much trash content, then you won’t get paid enough money on top of what it costs to produce those materials!
7) GPT – Grade Progressing Trend Measurement
GPT is a measure of the quality of cotton fibre. It is an important parameter for cotton quality and it can be defined as the ratio between weight and length.
GPT is a measure of the strength and elasticity of cotton fibres. It also expresses how much force it takes to break or rupture a given piece (i.e., breaking point). GPT values range from 0% (no strength) to 100%, which means that all fibres in your sample have been completely broken apart by one another during testing procedures
8) Color grade
This parameter is used to determine the color grade days. The value of this parameter can be used as a guide in determining the dyeing date. If you have more than one color material, then you can use this parameter for each material separately.
HVI Parameters Measure Final Quality Attributes Of Cotton Bale
HVI parameters are used to measure final quality attributes of cotton bale. These parameters include:
- Weight (W)
- Length (L)
- Width (W)
The HVI parameters are taken into consideration in order to evaluate the cotton bale’s final quality attributes. The HVI parameters are used by cotton manufacturers to determine which processing steps need to be undertaken, or whether they should improve the quality of the material further.
What is staple length in cotton? Complete definition.
Staple length is the major characteristic of cotton fiber on which cotton is traded and its price is determined. Staple length is the length of fiber. This parameter of cotton is so important that every consumer has to first decide what yarn he wants to produce and what staple length of cotton will be required to produce this yarn. In different origins staple length of fiber is spoken with different length scales like inches, MM milli meters and in USA mostly 32nds.
Here are a few staple lengths and their importance and definition also described for better understanding.
Staple length below 27 mm is considered short staple cotton and mostly used for yarn counts below 20/1 ring yarns or low quality or cheaper yarns like open end depending on the requirements of demands.
Major portion of global cotton consists of the staple length between the range of 27 to 30 mm fiber length. This sort of cotton is used to produce medium to good quality yarns. Count range mostly from 20/1 to 40/1 carded or combed for weaving or knitting.
Above this is long staple cotton with staple length 30mm to 33 mm. This cotton is used for producing fine quality yarns from 40/1 to 80/1 combed and compact yarns which are used for light weight fine quality fabrics.
Cotton with 33mm above is called ELS or Extra-long staple cotton used for very fine yarns, high strength or tenacity yarns.
What is Uniformity Index UNF in cotton testing?
Uniformity Index of UNFI is a ration of mean length with upper half mean length. it is calculated by HVI or Fibrogram cotton testing instruments.
We are giving the following details for the ideal or poor counts of Uniformity.
1. Uniformity Index of Unf below 77 is considered very low or poor uniformity.
2. Uniformity index between the range of 77 to 80 is called low uniformity.
3. Uniformity Index Unf from 80 to 84 is considered medium level. Mostly normal quality cotton contains this range.
4. Uniformity Index 85 to 87 is considered high level uniformity.
5. Uniformity Index above 87 is considered a very high level of uniformity.
What is (SFI) Short Fiber Index In cotton HVI report.
SFI Short fiber index is a very important parameter in cotton results as it determines the ratio of short fiber in cotton. SFI indicates the %age of fiber having less than half inch length. This ratio is counted on High Volume Instrument HVI, one of the latest and best cotton testing instruments being used in the textile sector. The higher SFI is usually considered bad in cotton results.
SFI below 6.00 is an indication that cotton has very little fiber which is good for cotton consumers. But this sort of cotton is rarely available.
Normally and mostly cotton contain SFI between the range of 6 to 9 and it’s acceptable for most cotton buyers.
SFI short fiber index from 10 to 13 is considered a little higher side ratio but to some extent acceptable for the cotton consumers.
SFI short fiber index above 14 is usually not acceptable for yarn manufacturers who want to make fine quality yarns and they avoid buying cotton with such high value of SFI.
What is Rd and +b in cotton and its definition?
Both Rd and +b are the color grade parameters for cotton. Rd describes the reflectance in cotton. Higher rd indicates the brightness in cotton while lower rd reflects the dullness or grey look in cotton. Cotton having higher rd is considered the better cotton and it also adds to its value and price.
While +b in cotton indicates the yellowness in cotton. Both these units are tested or measured on fiber testing machine HVI (High Volume Instrument) Earlier Fibro graph machine was used to test the cotton results but now a days majority of labs and mills use HVI machine with latest features.