ASME B18.18.1-2007 pdf free download.Inspection and Quality Assurance for General Purpose Fasteners.
1 GENERAL IN FORMATION
1.1 Basic Plan Structure
This Standard outlines a Quality Assurance Plan for internally and externally threaded fasteners and accessories or associated parts. Provisions are included for sampling plans, inspection frequencies, control procedures, and record keeping.
Included in this plan are fasteners for general purpose applications, such as those where hand assembly is employed and cost is probably of prime consideration. This plan relies on judicious manufacturing controls and inspections by the producer and, should a dispute arise, provides an inspection plan for lot compliance after shipment.
This Standard will be used in conjunction with other accepted standards for product, testing, gaging, and material; therefore, those provisions, as well as packaging, are not included herein.
1.2 Inspection Levels
The substantial difference in importance to the user of various characteristics and the dissimilar degrees of control in manufacture make impractical the subjecting of all characteristics to the same degree of inspection. Therefore, three inspection levels have been provided.
Any additional characteristics deemed applicable by the user that do not appear in the plan shall be explicitly designated by the user, preferably on engineering drawings and related specifications by the appropriate code letter at the time of ordering (see Nonmandatory Appendix B). To assist in arriving at the most appropriate inspection level, the Decision Table included in Non- mandatory Appendix A is recommended for guidance.
1.3 Lot Sizes
When the acceptance number for sampling by attributes is fixed, variation in sample size results in variation of acceptable quality. Therefore, to avoid this inconsistency, fixed sample sizes are applied for the greatest range of lot size. Sample sizes for lots up to 250,000 pieces are shown in Table 1; however, for lot sizes exceeding 250,000 pieces, Table 1, Note (2) shall apply.
1.4 Measuring and Testing Equipment
All inspection and testing equipment shall be calibrated and traceable to the National Institute of Standards and Technology (NIST) standard or an equivalent
national or international Standard. All calibration procedures shall comply with the requirements of ISO 1 7025, General Requirements for the Competence of Testing and Calibration Laboratories.
1.5 Basic Plan Outline
The basic plan outline as shown in Fig. 1 is included to enhance understanding and use.
1.6 References
The following is a list of publications referenced in this Standard.
ASME Bi .3M, Screw Thread Gaging Systems for Acceptability — Inch and Metric Screw Threads (UN, UNR, UNJ, M, and Mi)
Publisher: The American Society of Mechanical Engineers (ASME), Three Park Avenue, New York, NY 1001 6-5990; Order Department: 22 Law Drive, P.O. Box 2300, Fairfield, NJ 07007-2300
ISO 17025, General Requirements for the Competence of Testing and Calibration Laboratories
Publisher: International Organization for Standardization (ISO), 1 rue de Varembe’, Case Postale 56, CH-121 Gene’ve 20, Switzerland/Suisse
2 GENERAL PURPOSE FASTENERS
2.1 Scope
This Standard outlines the inspection plan to be employed when lot compliance after shipment of general purpose fasteners is questioned by the user. The producer is responsible for supplying a product of satisfactory quality through judicious manufacturing controls and inspection.
2.2 Applicable Characteristics
The general plan outlines the significant applicable characteristics that are described by related specifications and engineering drawings. Three levels of inspection — A, B, and C — are employed. Each characteristic is assigned an appropriate level. These characteristics and corresponding inspection levels are listed in Tables 1 through 3 for various types of products.