ASTM D2258/D2258M-16

5.2.1 If not specified by the purchaser, the manufacturer will define suitable production lots based on one or more of the following: supply lot, production shift/time segment, production equipment or production line, operator, designated shipment, production run, or a combination herein.

5.2.2 If not specified by the purchaser, the manufacturer will define sampling and testing frequency based on the following: process capability or capability analysis, historical trends, level of detection rate required, confidence level requirements, known variations or special causes, or both. Every attempt to ensure conforming product is being produced, identify potential nonconforming product or proper isolation and identification, will be carried out by the manufacturer.

5.2.3 Sampling count and number of specimens will be based on standard practice listed within the document. Increase or decrease in count or frequency might be applied based on typical standard deviation, precision and confidence level, Measurement System Analysis (MSA), gauge R&R study, or gauge linearity and bias study. Higher variations would indicate reason for an increase in count, while lower variations would indicate reason for decrease in count, while lower variations would indicate reason for decrease in count.

5.2.4 When selecting a suitable sample size, several considerations need to be made: (1) size of the lot being sampled, (5.2.5 Minimizing and reducing measurement error will improve product testing reliability, reduce overall variation of test data accuracy, and improve confidence level of the reported values.

5.4.1 Estimate the variance due to lot samples, the variance due to laboratory samples, and the variance due to testing specimens.

5.4.2 Calculate the total variance for average test results for several combinations of the number of lot samples, the number of laboratory samples per lot sample, and the number of specimens per laboratory sample.

5.4.3 Calculate the cost of performing each of the sampling schemes considered in 5.4.2.

5.4.4 Select the sampling scheme that (1.1 This practice describes a procedure for the division of shipments of yarn into test lots and the sampling of such lots for testing.

1.2 This practice is applicable to single, plied, or cabled yarns, and cords, made of any fiber or mixture of fibers, and supported on any form of package, including beams.

1.3 This practice also describes procedures for the sampling of yarn(s) removed from woven or knitted fabrics; however, when thus sampled, the yarns are usually not representative of entire shipments, as referred to in 1.1. Consequently, the resultant sampling can only be used to determine the characteristics of the yarn and is usually not used for acceptance testing. Moreover, it should be recognized that the characteristics of yarns from fabrics may be different than the characteristics of the same yarn(s), prior to being entered into the fabric manufacturing process.

1.4 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.

1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.