The origin and application of MIL - std-105e sampling table

MIL - STD - 105 - e sampling plan is also called count gather sampling plan, purchasing munitions during world war ii U.S. military weapons and equipment, for all the supplier to the acceptance inspection, process inspection, product inspection, in the form of outgoing inspection and strict inspection to ensure the quality of weapons and equipment, but as a result of types of products and sharply increased, and the process is complicated, the previous inspection system cannot respond to this trend, and use audit inspection methods developed by the sampling plan.

The term and symbol of sampling inspection

1 sampling inspection, such as by a group of products or materials, scattered, random a certain number of samples, in accordance with the project inspection or test, the results and determine the benchmark, to determine the whole batch of qualified or not qualified the job.

LOT: a collection of products produced under same conditions.

Send inspection approval: send the approved batch.

LOT SIZE: the total number of individuals tested in the delivery inspection is usually represented by N.

SAMPLE: the product that extracts the job test object from the batch.

SAMPLING: SAMPLING from the batch.

SAMPLE SIZE: the number of samples is represented by n.

8. The number of qualified judgment: the sample contents may contain the highest number of defective products when the approval is qualified, which is expressed by Ac or c

.

The number of unqualified determination: the number of the least defective products contained in the sample is indicated by Re.

Sampling inspection plan: stipulates the sample size, the number of qualified judgment to decide whether to send the inspection to be qualified or unqualified, this combination is called the sampling inspection plan.For example, n = 50, c = 2 is the sampling inspection plan.

ACCEPTABLE QUALITY LEVEL AQL (ACCEPTABLE QUALITY LEVEL) is also known as ACCEPTABLE LEVEL, for approval

The quality satisfaction limit is expressed as Po when the batch is defective.The quality of the consignment has reached this level and the consumer is willing to accept it as much as possible.

2. Defect DEFFECT classification method

Any of the characteristics and specifications of the products shall be referred to as the defects in the design and the contract.It is usually divided into the following

At all levels.However, other classification methods may be adopted or subdivided into these grades.

2-1 serious DEFECT (CRITICAL DEFECT) :

Also known as dangerous faults, means the judgment or experience, think this drawback will be able to make the maker, equipping or user has injured or unsafe when possible, or cannot perform its final products or the disadvantages of the products should have the function of.

MAJOR defects:

Means no serious shortcomings, the use of performance products unit, cannot achieve the desired purpose, or significantly reduce use nature actually caused by the customer or users are not satisfied, and will be return.

2-3 MINOR defects:

The term refers to the use performance of the unit, may not be reduced, or although it is inconsistent with the specification, it has no effect on the use and operation of the utility.

3. ACCEPTABLE QUALITY LEVEL: (ACCEPTABLE QUALITY LEVEL, AQL)

AQL is the highest rate of failure that consumers consider satisfactory.Usually the same AQL sample size is higher than the sample hour.The order of AQL in the 105D table is from 0.01 to 0.10 with a level of 5, 0.10 to 1.0 has a level of 5, and 1.0 to 10.0 also has a level of 5, which is arranged in a geometric series of 5, 10, and the second AQL is 1.6 times that of the previous AQL.When the AQL value is below 10.0, the number of defective or hundred defects can be expressed in terms of more than 10.0.The sample size is also arranged in a series of 5 10 series.

4. Inspection standard:

General inspection level I, II, III level 3, unless there are special provisions, use the class II inspection level, but not too much understanding, can use grade I standard, need higher understanding level III level is used to test.Another special test level has s-1, s-2, s-3 and s-4.Is that I wish to small sample sizes, the use of special level when the batch is great, or inspection cost is very high, and allows a greater hazard rate, or destructive test, special standards can be used for sampling plan.

5. Determination of acceptance and rejection:

5-1 sampling time, if the bad product in the sample is d:

D. The Ac is acceptable

D. The negative number is rejected by Re

(normal or strict check Rc = Ac + 1)

If the first sampling d1 bad product is first sampled, if the first sampling d1 is not good, then the second sampling is of d2 defective products:

The first sampling of defective products has d1

D1 acceptance

2

In the first sampling of Ac1 < d1 < Re1, the second sampling is done, with d2

The (d1 + d2) is acceptable

(d1 + d2) Re2 rejected

(normal or strict check Re2 = Ac2 + 1)

5-3 times of sampling, the number of defective items in di table I sampling is:

Σ di Aci ≦ acceptable

Σ di Re1 ≧ rejected

Aci < Σ di "Rei sampling again (I = 1, 2,... 7, and normal or tightened inspection Re7 = Ac7 + 1)

6. Brief history of AQL:

The AQL was originally proposed by the Ordnance Department of U.S. Army.By Bell Telephone Laboratories (Bell Telephone Laboratories) engineers mainly set up by The group, published in 1942, The Ordnance Tables. After some correction and expand and develop into The Army Service Forces Tables, table contains a single and double sampling plan, and applications, with double sampling plan is preferred.

The Statistical sampling table of SRG's navy was developed by the Statistical Research Group of Columbia University in 1945. This table is similar to the Army Service Forces tables, with some differences except for multiple sampling plans.

In 1949, JAN - std-105 was developed by the integrated land and navy individual sampling table, and the jan-std-105 table was replaced by the MIL -std-105a table in 1950. The form of the MIL -std-105a table was similar to the standard table mentioned above, and there were some modifications.In 1958, the MIL - std-105b was changed to MIL - std-105b, which was changed to MIL - std-105c in 1961.

From 1960 to 1962, by the United States, Britain and Canada and other countries of the military representatives committee said ABC work group, make joint count value of the three general sampling table, the table is originates from the AQL system, and published in 1963 for the MIL - STD - 105 - d table, but to honor its international, is named as ABC - STD - 105.

The use of the sampling table of the two - MIL - std-105d (or abc-std-105)

1. Specified delivery test batch N.

2. Determine acceptable quality level AQL.

3. Decides to adopt single, double or multiple sampling methods.

4. Select the quality of inspection, unless specifically specified, generally using level II.

5. Sample representative in table (6-1) by batch N and inspection standard.

6. Depending on the severity of sampling methods and inspection (start selects the normal inspection), respectively, using the "normal", "strict", or "decrement inspection table", by the generation of words and the AQL value Chad sampling plan.

7. Use the intersecting column of each table and the AQL value to obtain the sample size n.

Example:

A. BATCH SIZE: 1000PCS.

B. MAJOR DEFECTIVS AQL = 1.5 acceptance criteria.

C. Secondary weaknesses (MINOR DEFECTIVS AQL = 4.0) acceptance criteria.

D. SAMPLING by SINGLE SAMPLING PLAN.

E. adopt LEVEL II INSPECTION LEVEL (INSPECTION LEVEL II).

F. The conditions of a-e are identified by the sample table (6-1) as "J", and then the table (6-2) single normal inspection table:

Sample size (i.e. the number of products to be tested) : 80PCS

The number of cases must be at least the square root value of the total number of boxes, for example: the total number of boxes is 200 cases and the number of cases shall be at least 15 cases.

MAJOR DEFETIVES:

While AOL = 1.5 acceptance level, the acceptable number of defective products is 3PCS = Ac.

The rejected defective number is 4PCS = Re.

MINOR DEFECTIVES:

While AQL = 4.0 acceptable level, the acceptable number of defective products is 7PCS = Ac.

8PCS of defective products are rejected.

By Syria's condition and check the data, that the goods are doing this for you to follow the sampling inspection standard, then you can be in accordance with the actual standard of bad play and number of consistent or difference as the judgment of this shipment is acceptable or rejected.

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Single Sampling plan for Normal Inspection is generally tested

If the sampling number is equal to or greater than the number of batches, the test will be 100%.

Arrow = use arrows to move up the first sampling plan.

Ac = allowed, Re = rejected.