AQL Inspection Manual
AQL sampling inspection plans are designed to protect the supplier from having good lots or product rejected based on an inspection of a limited sample if the defects are within the specified limits. Since the inspection is based on sampling, there is some risk that good lots may be rejected. However, the supplier risk of rejection is low. This manual is designed to give the reader a basic understanding of AQL sampling inspection, its application and some feel for inspection levels and AQL's.
The AQL Inspector's Rule is a slide rule device for quickly finding AQL sampling plans. Its straightforward design makes it very easy to use. All the data is conveniently grouped so that the sampling plan can read off instantly. The rule covers a wide range of AQL's (.065 to 15), and Normal, Tightened and Reduced inspection levels for both single and double sampling plans.
Besides being a time-saving tool on the job, the AQL Inspector's Rule, combined with the Manual, makes a useful training aid.
AQL sampling inspection currently enjoys wide acceptance for inspection by attribute. The specifying of AQL plans by the Department of Defense has greatly increased the role of this method of sampling. Originally specified in MIL-STD-105E, the department of Defense discontinued this standard in February 1995 and users were referred to its commercial equivalent: ANSI/ASQC Z1.4-1993.
In December 2003 the ANSI/ASQC Z1.4-1993 was replaced by the ANSI/ASQ Z1.4-2003 standard.
The ANSI/ASQ Z1.4-2008 standard is a reaffirmation of ANSI/ASQ Z1.4-2003.
The ISO standard for the inspection by attributes was introduced in 1989 as the ISO 2859-1:1989 standard, matching the ANSI/ASQC Z1.4-1993 and MIL STD 105E standards. The ISO 2859-1 standard was modified, including changes to the sample plans, in a 1999 revision.
AQL sampling plans and procedures have also gained popularity for many non-defense and industrial applications. In addition, AQL has been adopted by Canada and Great Britain as an International Standard ABC-STD-105.
The complete ANSI/ASQ Z1.4-2003 standard is available from ASQ, item T004 or T004E, Customer Service Department, P. O. Box 3066, Milwaukee, WI 53201-3066. (414) 272-8575 or (800) 248-1946