ASME B18.18:2011 pdf download

ASME B18.18:2011 pdf download.Quality Assurance for Fasteners
1 GENERAL INFORMATION
1.1 Scope This quality focused Standard establishes in-process and final inspection requirements for fastener products as well as a receiving inspection plan for fastener pur- chasers. This Standard identifies four categories, recog- nizing that fastener users have widely varying requirements. The four categories covered are as follows: (a) Category 1 — A receiving inspection plan for purchasers (b) Categories 2 and 3 — Utilizes documented and verifiable in-process controls structured at the produc- er’s discretion (c) Category 4 — Includes all of the requirements of Category 2 plus 100% inspection for a specific feature or features In the preparation of this Standard, it was recognized that its function must enable it to be a part of the various regimens in use today that attain certain quality levels of products. This Standard was written to encompass frameworks that enable the users of this Standard to pinpoint which category they wish to use in meeting their own objectives.1.3 Measuring and Testing Equipment All inspection and testing equipment that is used for the acceptance of Category 2, 3, and 4 fasteners shall be calibrated by a laboratory that has been accredited to ISO/IEC 17025 by an accreditation body that operates in accordance with ISO/IEC 17011. Calibration shall be traceable to the National Institute of Standards and Technology (NIST) Standard or an equivalent national or international standard. 1.4 Terminology For definitions of terminology not specifically defined in this Standard, refer to ASME B18.12. 1.4.1 Lot. A lot is a quantity of product of one part number made from a single heat of raw material by the same production process and subsequently submitted for final inspection at one time. In the case of fastener assemblies, such as screw and washer assemblies, the manufacturer shall maintain lot traceability for all components. 1.5 Designation of Final Inspection Category Procurement documents should indicate which cate- gory (2, 3, or 4) of final inspection is required. Examples of designation are provided under the appropriate inspection category sections of this document.
2 BASIC PLAN REQUIREMENTS
2.1 Understanding the Basic Requirements The following information applies to all fasteners pro- duced to any applicable category contained within this document.This Standard places a Cp0 expectation on the sample plans shown herein. However it should be recognized that zero nonconformities (Cp0) in a sampling does not necessarily mean that the population is entirely free of defects. Statistical process control and other variation low- ering measures can significantly reduce the number of defects in the population that may be produced, but it should be noted that statistical indices only imply the quality level produced, and improperly applied statisti- cal treatments will imply the presence of defects that are not present, or miss some deficiencies altogether. The closest that one can approach zero defects in a population is through 100% part per part examination, but again caution must be exercised. The goal of zero here can be intractable. The complexity of resources required, the limitations of the available equipment for each verified characteristic, the stringency of controls required will only be able to demonstrate quality on a parts per million (PPM) basis, and not necessarily any assurance of zero deficiencies. 2.2 In-Process Inspection 2.2.1 Fabricating Operations. General inspection procedures shall be established on the basis of engi- neering and manufacturing experience with regard to the effort of setup, tooling, operator, machine setup, and operation on each characteristic at each processing station. The minimum in-process requirements at each machine or processing station shall be as follows: (a) Five pieces shall be visually examined for gross defects and surface discontinuities as required by the applicable standards. Three pieces shall be verified for part characteristics imparted to it by that machine or processing station in accordance with Table 1 at the following times: (1) at the start of each production run (2) at the start of each new shift (3) when a tool is changed or when an adjustment in machine setup is made (4) at the completion of each manufacturing operation