As a result of the advancement of modern technology in all branches of production, particularly in the textile industry, the control of materials is increasingly indispensable, from the reception of the raw material to the exit of the yarn or fabric as a final product.
|Quality control of geometric properties|
Quality control of mechanical properties
Quality control of retentive properties
Quality control of geometric properties:
The grammage or weight of the tissue is one of the most important parameters of the tissue. The weight is used to check the correct realization of the fabrics, as it determines the amount of material used in its manufacture. It is expressed in grams per square meter, it can also be transformed into weight per linear meter.
The test that determines the weight is very simple to perform with a balance and a cut prove. The probe is cut in a circular shape, corresponding to a square of dimensions 10 x10 centimeters…. Once the probe is cut, it is weighed directly on the balance. The data obtained must be multiplied by 100 to obtain the weight per square metre. According to norme UNE 12127.
2.- Density of the tissues
The measurement of the density of the fabrics refers to the threads and passes that the fabric has per centimetre. The measurement is made by observation and direct counting of threads and passes contained in a centimetre in the shed fabrics. The thread counter is the device used, which fulfills two missions, that of increasing the vision by its magnifying glass effect and delimiting a certain length.
The ligament is defined as the order of interweaving of the warp and weft yarns in the openwork fabrics. Checking the weave ligament is important to control the correct execution of the weaving process. It is checked by direct observation of the sample. The device used is the thread count as a magnifying glass. The standards norms are UNE 40017 and UNE 40161.
4.- Dimensional stability
In the case of fabrics and garments in which the dimensions must be stable, especially when washed, it is advisable to carry out a simple test run on a common washing machine.
This test can also be carried out in a more controlled way, by means of specific rules. The washing machine is tested according to the following standards is called Wascator.
a simple way it would be enough to mark a length, fifty centimetres, both in the warp or longitudinal direction and in the weft direction or transverse. Subsequently, a wash is carried out at 40ºC and a program of normal washing. The sample is then air dried after which remeasures the lengths of the marks made.
The result, expressed in percent, gives us a real idea of the dimensional stability of this fabric. (3% maximum)
5.- Tissue deformation and distortion
The UNE 40.079 standard describes the methods for determining the possible distortions between the two series of threads, warp and weft, which make up the tissue and which must form a right angle between them.
Such distortions, which may affect the presentation and appearance of the fabric, are considered definable in these possibilities:
- “Warp or weft arching”: When one or the other is not arranged in a rectilinear fashion.
- “Double arcing”: When the tissue is arcing by in such a way that the sense of the same is opposite between some zones. of the tissue and others.
- “Bias”: When the warp and weft are not arranged at right angles.
In these cases, on the sample or piece previously conditioned for at least 24 hours in the normal test atmosphere, is determined by means of a ruler and square graduated in centimetres and millimeters, the maximum amplitude of the deformation.
Figure 1 shows the operating procedure for measuring the arched warp as the greatest perpendicular distance between the straight line joining two points 250mm apart from the selvedge of the fabric.
Similarly, to measure the greatest perpendicular distance between the line joining the two extremities of an arched pass and the furthest point from it, the graduated ruler (Figure 2) is placed across the tissue, so that one of its edges cuts the selvedges together with the determined pass. Slide the square and check the maximum arrow of the mentioned pass in relation to the ruler.
Double arcing is measured as the smaller side of the capable rectangle. to contain the last Z, so that the other side of the rectangle is parallel to the line joining the two points at which the short pass the selvedges. Figure .3
Bias is measured as the distance between the end of a pass and the point on the same selvedge, intersected by a line from the other end of the pass and perpendicular to the warp (Figure 4) expressed as a percentage of the width of the fabric.
Quality control of mechanical properties:
1.- Tensile strength
Tensile strength is the resistance of the fabric to breakage and is of particular importance in determining the use of the that a tissue is destined. In the case of fabrics with applications the knowledge of this value is determinant in the use of the product. of the fabric.
Another of the parameters that is analyzed in the realization of this test is the increase in length when applying a tensile force, in the elongation of the tissue.
The resistance can be measured in the fabric, in the seam, in the case of confections, as well as in the tear.
The equipment used is the DYNAMETER, basically by a pair of clamps, one clamp is fixed and the other mobile, the latter being responsible for making the effort necessary to produce the breakage of the fabric.
2.- Resistance to wrinkling.
Wrinkles are small folds -more or less- that are more or less marked wich are randomly distributed on a textile surface, altering their smoothness.
They appear during the manipulation of the tissues and in the use of the cloths, and are caused by stress and flexion. In other times we may need a permanent wrinkle and therefore not will help to know the tissue that will behave best.
The analysis of the wrinkling serves to test the capacity of a to recover its original shape after undergoing a load.
The norm to follow is UNE-EN 22313:1993 Textile Textiles.
3.- Resistance to the hooking of the fabrics
In order to check the resistance of the fabrics to the hooking, this test is performed, which is described in the ASTM standard. 3939.
Specially designed for knitwear. The textile article covers the cylinder, which is clearly seen in the photograph, and takes contact with the ball full of tips. The turning movement of the cylinder, each full turn is called a cycle, which has contact with the cylinder. the ball produces the couplings.
After the time described in the standard, the resistance is evaluated by direct observation and comparison with standard photography.
The score ranges from 1 to 5, with 5 being the strongest.
Quality control of the retentive properties:
Solidity to light: with this name we designate the resistance to modification of a tincture due to the effects of daylight. The most commonly used device is the Xenotest. The test is performed according to the norm UNE-EN-ISO 105 B02 2001, in which the performance, equipment and test conditions are indicated. The assessment will be performed visually by more than one person, who will compare the degradation of the dye and the degradation of the scale of blues. Rating from 1 to 8.
– Resistance to washing: with this test we designate the resistance to the modification of the colour of a material subjected to washing. The device used for this type of test is the Linitest which consists of a container with water to act as a bain-marie. The test follows the procedure described in standard UNE-EN-ISO 105 C06 1997. An ECE standard detergent is used.
– Solidity to rubbing: with this name we designate the resistance to the modification of a dye subjected to the effects of rubbing. The device used for this type of test is the Crockmeter. The test is determined by the UNE-EN-ISO X12 2003 standard.
– Solidity to rubbing with organic solvents: this test is performed in the same way that the solidity to the rub but wetting the witness with solvent.
– Solidity to the ironing: with this name we designate the resistance of the dyeing of textiles of any nature and in all its states of transformation to the current ironing or by treatments on hot cylinders. The test follows the standard applied UNE-EN ISO 105-X11:1997. The apparatus used for this type of test is the Fixotest.
– Water fastness: the solidity of the tinctures is valued to the immersion in water, in textiles of any nature and in any condition of transformation, by means of white witnesses. The test follows the standard UNE-EN-ISO 105 EO1 1996. The instrument used is the Pespirometter.
– Sweat fastness: the solidity of the tinctures is valued in the textiles to the action of sweat produced by the human body. For this test is used the Pespirometter. The test follows the UNE-EN ISO 105-E04:1996 standard.
– Solidity to bleaching with hypochlorite: the solidity of the dyes in textiles to the action of bleach. Standard used UNE-EN 20.105-N01:1996.
– Solidity to dry cleaning: the solidity of the dyes in the textiles is valued to the action of perchloroethylene. The test follows the standard UNE-EN-ISO 105 D01 1996. The sample is analysed in a bag made of standard cotton fabric.
The light box is the place where all solidity assessments must be made, placing the samples horizontally on a white or neutral background and with the required standard illuminant, the D65 daytime illuminant is normally used.
Abrasion resistance is based on two fundamental principles: the first corresponds to the number of cycles required to produce the yarn breakage and the second in the calculation of the average loss rate of tissue mass.
The methodology is mainly based on the determination of the number of of cycles necessary to break two threads in the event that it is a Fabric intended for decoration and three threads for fabrics intended for Upholstery.
To determine the abrasion resistance of the tissues is usually Use the UNE-ENISO-12,947 standard in which all the Parameters required for the performance of the test,
As well as the materials and equipment necessary to carry out the test.
In all the uses to which a tissue may be subjected, the resistance to abrasion
It’s usually much more important than its tensile strength. To This respect can be said that the ligament or texture plays a role Important.
The test conditions also influence the outcome, The type of abrasive surface is to be considered, the pressure on The fabric, the tension to which it is subjected etc.
The abrasion resistance determined in a laboratory is one of the factors that most
It contributes to the prediction of the behavior of a tissue in its later use.
Apparatus used for conducting tests:
The so-called pilling effect is a phenomenon that has been known for Time in the textile field. It is presented in textiles composed of Fibers, especially if these items contain synthetic fibers.
The pilling is manifested on the surface of the tissues in the form of small balls of varying dimensions produced as a result Of the physical-mechanical process to which the ready-made garments are submitted During use, especially as a result of the friction of the Certain areas of the fabric with itself and/or with other elements External. These masses of fibers are retained in the textile by Other anchor fibers, giving the fabric an unpleasant look that It constitutes the first symptom of ageing and wear of the garment.
Finishing and sizing operations that reduce the tendency to pilling:
- Thermosetting: This process fixes the position and torsion of the fibers, preventing them from protruding from the whole.
- By this operation, it is possible to remove the Ends of the fibers on the surface of the fabric. In the case of the Chemical fibers must be aware that their fused ends They absorb a greater amount of dye than the rest of the fiber and They dye, therefore with a more intense tone. Scorching operation It should usually be done after the dye, except for When using the litmus procedure.
- Hot calendering: Produces a compacted crushing and Smoothing of the surface of the fabric as well as an effect of Fixation of the fibers, diminishing their migration to the surface of the Tissue.
- Tundido: There are several treatments,
- Resins that imprison the fibers, avoiding their migration to the surface of the fabric
- Silicones that reduce the abrasion of the surface of the fabric, delaying the formation of pellets.
Essays: The most used is the UNE-EN-ISO 12945-2.
It is carried out with the abrasion tester Martindale.
The evaluation table when determining the degree of pilling of The tissues, will be common for all regulations, whatever the Test method to be used:
5 – NO VISUAL CHANGE
4 – SUPERFICIAL VILLI AND OCCASIONAL PIL
3 – MODERATE PILLING TRAINING
2 – VISIBLE AND ABUNDANT PILLING
1 – PILLING VERY INTENSE ON ALL SURFACE
AIR AND WATER IMPERMEABILITY
The air-tightness measurement is carried out in the air Permeabilímetro according to The standard une-en 9237. This unit measures the amount of air that is capable of traversing the fabric.
The water-tightness measurement follows the process of the standard une-EN 20811 The test apparatus, Permeabilímetro to the water.
Measure the amount of water that the fabric supports Until the appearance of the third drop, the result is expressed in mm.
WATER REPELLENCY OF TISSUES
The determination of the capacity to repel the water that has a tissue is measured with the Sprau-test, according to Norm une-EN 24920 and the result is expressed by comparison with standard.
The behavior of certain tissues preventing the passage of water and Allowing the passing of our perspiration, in the form of steam, is a Desirable effect for certain tissues. This feature increases the feeling of comfort. The ability of impermeability/breathability Take advantage of the difference in the size of the water in its different states of liquid and vapor.
THE water vapor resistance test is based on the resistance That offers the tissue to the passage of the water vapor that is produced in the Plate of the team. The test is carried out according to UNE en 31092 Equivalent to ISO 11092
MEASUREMENT OF THERMAL INSULATION CAPACITY
Due to market demands, new trials are emerging In order to predict in a way as objective as possible the Product behavior in the face of real situations. This is the objective of that essay.
EFFECTIVENESS OF OLEOFUGOS AND HIDROFUGOS
In this essay we want to know the behavior of the tissue Against liquid, possible sources of spotting. Many tissues have the property to repel Water (repellence) or repel different Oleófugos agents (Oleorepelencia) However other tissues that do not Initially present, they can acquire it with different processes of of the tissues. It is a product application Fluorocarbon that delay the penetration of water and fat to the Tissue.
- Repellence determination. 3M Test II method. The value of Water repellency of the tissue, is the test fluid of more than Something, which does not wet the tissue is a period of 10 seconds, (the Used test fluids are water and alcohol mixed in different proportions), obtaining a high number indicates a repellency el intendente la intendenta.
- Oleorepelencia determination. Standard: AATCC 118:1984 the AATCC value of repellency to the oil of the tissue, is the test liquid of number Which does not wet the fabric in a period of 30 seconds (the Used test fluids are hydrocarbons of different weight Molecular).
By ISO 20743:2007 This international standard specifies Quantitative test methods to determine the activity Antibacterial in finished textiles including Nonwovens, Arranged in a nutritious medium inoculated with the microorganism selected, to the growth of the selected microorganisms.
MEASUREMENT OF THE RESISTANCE OF LAMINATES AND BENDING
Through Dynamometry you can examine the cohesion of a material Susceptible to laminate, under well-defined conditions. Is Studies the strength of adhesion between the different layers of tissue or Between the fabric and the different layers of other materials such as foam foamizada.
RESISTANCE TO UV RAYS
There are different standards that determine the degree of protection of textiles against UV rays.
The most complete and also offers protection results After having subjected the textile article to a useful life (washing, Dry cleaning, abrasion, light…) Is: UV-Standard 801-1998. UV label.
Current fire-reaction trials focus on reproducing The most faithful way possible the actual conditions of use and evaluate the The most critical parameters of the product in question to ensure Highest possible safety in case of fire.
You can distinguish the following parameters to be measured:
- FLAMMABILITY OR EASE OF IGNITION
- FLAME PROPAGATION
- DROPLET OR PARTICLE SHEDDING
- HEAT EMISSION
- SMOKE PRODUCTION
AGEING IN CLIMATIC CHAMBERS
The behavior of the articles is studied (stability Dimensional, color changes, brightness…) When subjected to different Temperature and humidity cycles in specific chambers, following the Regulations of the builders.
The Kawabata evaluation System, KES is a system that allows to detect Quantitatively and objectively the touch of a tissue from the Analysis of a set of physical variables.
The following mechanical properties can be measured:
- Tension and Shearing
- Bending or bending