ASTM D5866-12(R2020) pdf free download

ASTM D5866-12(R2020) pdf free download.Standard Test Method for Neps in Cotton Fibers
5. Significance and Use
5.1 Entangled cotton fibers that form neps have two sources: those that occur naturally as the cotton fiber develops on the plant into lint that is ready to be harvested and those that occur from mechanical action in harvesting, ginning, cleaning, card- ing or from a combination of mechanical action. 5.2 This test method does not identify whether the neps counted and measured are a result ofseed variety, environmen- tal influences, type of harvesting, or a result of mechanical processing. However, this information can be obtained from studies where samples are taken from plants in the field before harvesting and ginning, before and after cleaning, and carding before spinning. 5.3 The measurement of nep size and quantity going into, and coming out of, a fiber processing stage are commonly used to make adjustments in the processing machinery to reduce or eliminate the generation of mechanical neps. Neps that remain in spun yarns have a direct influence on neps in fabrics. For almost all types of yarn or fabric, neps are considered defects. 5.4 This test method provides a consistent and repeatable measurement offiber nep count and size. Check cotton samples supplied by the manufacturer are used to verify consistent measurement levels and laboratory-to-laboratory precision. 5.5 This test method is considered satisfactory for accep- tance testing when the levels of the laboratories are controlled by the use of the same reference standard cotton samples because the current estimates of between-laboratory precision are acceptable under these conditions. If there are differences of practical significance between reported test results for two laboratories or more, comparative tests should be performed to determine if there is a statistical bias between them using competent statistical assistance. At a minimum, ensure the test samples to be used are as homogeneous as possible, are drawn from the material from which the disparate test results were obtained, and are randomly assigned in equal numbers to each laboratory for testing. The test from the two laboratories should be compared using a statistical test for unpaired data, at a probability level chosen prior to the testing series. If a bias is found, either its cause must be found and corrected, or future test results for that material must be adjusted in consideration of the known bias.
7. Sampling
7.1 Lot Sample—For acceptance testing, take lot samples in the applicable material specifications or, in the absence of such a document, as directed in Practice D1441. N OTE 1—An adequate specification or other agreement between the buyer and seller requires taking into account the variability between sampling units, between laboratory samples within a sampling unit, and between test specimens within a laboratory sample to provide a sampling plan with a meaningful producer’s risk, acceptable quality level, and limiting quality level. 7.2 Laboratory Samples—For ginned cotton testing, take the recommended amount of cotton fiber as indicated by the manufacturer from each sampling unit in the lot sample or subsamples from the lot samples. 7.3 For processing evaluations, take laboratory samples from processing stages while opening and cleaning lines are operating at normal production flow rates or from carding machines while they are operating at specific processing speeds. 7.3.1 Laboratory samples from opening and cleaning pro- cessing stages will be in loose fiber form and will require special handling to prepare test specimens. Please refer to the manufacturer’s specific instructions for the proper preparation and handling for testing. 7.3.2 Laboratory samples from carding process will be in sliver form ready for specimen preparation. The sliver labora- tory should contain a complete cross section of the entire card or comber web.