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Out Of Control

Accurate measurement, reproducibility are a must for quality deliveries and repeat business.<b>By Gary N. Mock, Ph.D., Technical Editor</b>

By Gary N. Mock, Ph.D., Technical Editor Out Of Control Accurate measurement, reproducibility are a must for quality deliveries and repeat business. Quick response and just-in-time delivery watchwords in the recent past become increasingly important as textile suppliers and purchasers alike seek to shorten the supply-side pipeline. However, the new watchword may well be quality assurance, as textile and apparel suppliers seek global sourcing with some assurance that items sourced in one part of the world will match items sourced elsewhere.

James H. Heal's four-head Nu-Martindale pilling tester is an entry-model version ideal for use in small test laboratories. Quality considerations mandated by the International Organization for Standardization (ISO) have forced suppliers to further update testing methods, explore opportunities for more rapid testing and develop entirely new test-method means of evaluation. Organizations in the United States and abroad have worked with the ISO to develop methods to evaluate crock fastness, dimensional change and skewing. Crocking, Dimensional Change And SkewingIn a recent interview with a major U.S. retailers laboratory supervisor who must struggle with evaluating the results of universal sourcing, the biggest customer concerns noted were crocking, dimensional change and skewing. The ability to predict and identify these, as well as other changes, before the customer calls with a complaint is key to the success of both the textile producer and the retailer.Crocking, or color transfer by rubbing one of the oldest textile tests should be considered the first test done in a textile laboratory. When a textile fails a crock test, it will most likely fail other colorfastness, washfastness or lightfastness tests. A major cause of crocking is poor dye penetration, fixation, or wash-off. The amount of color transferred from a textile surface to other surfaces by rubbing can be determined quickly with the official American Association of Textile Colorists and Chemists (AATCC) Crockmeter, available from Atlas Material Testing Technology LLC in Chicago. Ten back-and-forth rubs of a finger with a standard pressure and motion assures reliable and repeatable results for both dry and wet crocking tests.Shrinkage is another major reason for fabric rejects or consumer returns. Traditional home washing and drying tests for shrinkage and skewing take between 12 and 24 hours to complete. The Quickwash Plus® system, developed by Charlotte-based Raitech Inc., a partner of Atlas, dramatically reduces shrinkage test times to about 15 minutes to wash, rinse and dry most fabrics. This reduction in testing time allows textile mills and laboratories to improve their overall quality and productivity. The Quickwash Plus also has been successful in testing the efficacy of enzymes or bleaches on fabric, as well as the durability of applied finishes. (See Textile Testing For Quick Response, ATI, November 2000). AATCC recently reaffirmed Test Method 187-2001 for the Quickwash. JCPenney, as well as United Kingdom-based MarksandSpencer and Tesco Stores Ltd., approved the Quickwash for shrinkage testing.Currently, dimensional changes of fabrics are determined manually using a template or marking device and a percent ruler for calculations a tedious and imprecise methodology. However, the QuickView from Raitech eliminates both marking and measurement errors and the need for double-checking of marks, measurements and calculations. It was developed specifically for the textile industry and provides a quick and accurate way to determine fabric shrinkage results using digital optics and computer imaging software to calculate fabric measurements before and after washing/drying procedures. Two systems are available: the basic system uses a digital scanner, while the QuickView Plus model uses a CCD camera with frame grabber to photograph the fabric specimen. Additionally, QuickView Plus is capable of averaging multiple marks on a specimen, as well as marks from multiple specimens to provide statistical data. FadingConsumers expect apparel to look good after multiple launderings and dry cleanings. To ensure this expectation, it is vital to minimize characteristics that detract from a garments appearance, such as fading and pilling. Accelerated laboratory lightfastness testing instrumentation was introduced in the 1950s. Since that time, understanding of the effects of radiation has increased along with advanced technology. Test conditions, including irradiance, temperature and humidity, are carefully controlled in an accelerated laboratory instrument, assuring tests that are repeatable and reproducible. To keep abreast with todays technology, a new model Fade-Ometer® was introduced in January by Atlas. The new Ci3000+ Xenon Fade-Ometer was designed for the textile industry and meets the exacting test requirements of AATCC Test Method 16E and ISO 105-B02.The Ci3000+ uses an LCD-based operator interface for simplified test setup, improved diagnostics, automatic calibration and easy programming of user-defined test cycles. The patented Smart Damper system keeps the test-chamber environment extremely stable and compensates for changes in the ambient laboratory conditions. With the touch-screen display, all test parameters are displayed in one location. Another improvement is the Smart Light Monitor that will not allow the operator to begin a test with incorrect monitoring filters installed. These standard features ensure accurate and repeatable tests. PillingAny surface degradation, such as the formation of fuzz and pills, will affect the value of a textile material. Therefore, pilling propensity is an essential criteria for garments, as well as for automotive and upholstery fabrics. Since pills form gradually during wear or use, it is important to predict the tendency to fuzzing and pilling by means of accelerated laboratory-testing procedures. The aim is to simulate and accelerate the surface changes as they will occur in end-use. The Atlas Random Tumble Pilling Tester, available in two- and four-chamber models, has proven successful for the determination of fuzzing and pilling. Both models feature digital timers; air injection systems; and ASTM, German or French version impellers that rotate at a constant speed of 1,200 revolutions per minute (rpm). James H. HealandCo. Ltd., United Kingdom, offers the Impulse, a single-unit random tumble-pilling tester. For convenience, up to four units can be linked together to a single power and compressed-air unit. The Impulse is designed to comply with Part 3 of ISO 12945. Incorporating the requirements of ASTM D3512, Part 3 of ISO 12945 follows the Pilling Box and modified Martindale method. A new abrasion and pilling tester by James H. Heal is the Nu-Martindale, the four-head derivative of the standard six-head Martindale. This instrument will appeal to smaller test laboratories and lower-volume users.  I. Biermann of Schlafhorst AG, Germany, recently evaluated these test methods and pointed out some of the strengths and weaknesses. Samples can become lodged behind the rotor in the random tumble-pilling tester, but the test provides stresses similar to actual use. The Martindale tester, on the other hand, allows the sample to be firmly clamped and rubbed with a predetermined Lissajous pattern, which totally covers the fabric surface. Test results for both are evaluated by comparing the specimen with a set of five photographs. The assessment is subjective. Clearly, an automated scan with counting software would lead to a more reproducible assessment.  Yarn TestingDynamic or continuous yarn testing has been available for a number of years and is the cornerstone for reliably testing the quality of yarn. The new Dynafil ME from Textechno Herbert Stein GmbHandCo. KG, Germany, was developed to offer yarn friction, tension, and evenness measurements. With the use of a 1-meter-long heater zone, thermo-mechanical tests such as shrinkage (force) or draw-force (draw-tension) are possible. The Dynafil ME allows precision testing at speeds up to 1,000 meters per minute (m/min). With speeds of half the maximum, statistical analysis of a yarn package can be concluded in 10 to 20 seconds. The draw-force testing of POY, crimp testing, as well as shrinkage testing, are possible with all yarns.  Laboratory OvensLaboratory ovens have been used for a number of applications, from simple drying of lab dips to the attempted development of continuous-range chemical formulations in which time/temperature profiles and air balance are critical to the outcome. Many textile companies have expressed frustration because lab trials have not corresponded well to in-plant trials. SimTek Inc., Greensboro, N.C., entered the textile service industry by offering to upgrade the performance of existing tenter frame dryers using mathematical modeling. It did not take long for the company to realize existing lab ovens did not effectively reproduce the typical production environment. The new SimTek Laboratory Oven features a calibrated airflow system and a built-in, fully functional computer with touch screen. Now the operator can enter oven temperature set point and fan rpm, as well as set critical temperatures and dwell time. By duplicating a production environment on a laboratory scale, then integrating modern data collection systems, SimTek has set a new standard for lab oven accuracy and usability. Production Testing
A key element in successful quick response is to replicate production conditions in a short amount of time. To this end, SDL America Inc. of Charlotte has developed its Quickspin/Quicknit testing machinery. The system enables the conversion of 5 grams of fiber to 1 meter of blended sliver to 200 meters of yarn to a knitted fabric in 15 to 20 minutes. The SDL MDTA-Rotoring produces a 1-meter ring of sliver up to 5 grams in weight from a single fiber type or blends. Blending is achieved on the machines conveyer by hand-tufting. A high-speed opening roller and rotor system also removes trash and dust, which can be determined at the same time. Test time for a double passage is five minutes.The resulting sliver is processed into yarn using the Quickspin single-position rotor-spinning machine, using a standard Rieter R20 spinning unit with each element individually driven and controlled via a microprocessor. This control allows spinning of yarn that replicates production yarns from rotor or ring-spinning systems. Interchangeable rotors, faceplates and navels allow spinning of a wide range of fiber types, counts and twist ranges at speeds up to 120,000 rpm. Test duration is three to six minutes, depending on yarn count.While the Quickspin yarn can be assessed for appearance, hairiness, evenness and strength, there is often a need to process it into fabric for color matching of blends or for further processing such as dyeing or finishing. The Quicknit system rapidly converts the yarn into a tubular sock format ideal for fabric testing, processing or color matching. The Quicknit is designed around production hosiery machine components and drives for ease of operation without requiring specific knitting knowledge or training. Tensile Testing
Zwick USA, the North American subsidiary of the Zwick Roell Group of Germany, provides the zwicki to test tensile properties of filament-type products such as yarns, twisted threads and cords or of flat, structured items such as fleece knitwear and fabrics. The zwicki is a high-quality, simple-to-use, low-cost and space-saving universal testing machine. It is suitable for production control, control of goods received and reliable quality assurance testing. Zwicks roots in the textile industry go back to the 1980s, when Zwick CRE testing systems began replacing manual machines in the testing of wide and narrow elastic fabrics. Since then, more than 100 Zwick systems have been installed in North America for a wide range of applications across the textile industry. The bottom line for all the products and processes detailed in this report is that, whatever a companys needs may be in meeting todays quality requirements, measurement and reproducibility are essential to meeting customers needs. Repeat business follows quality deliveries. April 2002



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