HRN ISO , Larson nomogram, operating characteristic curve of the acceptance plan, statistical quality control attribute acceptance plans, sampling. Fortunately, Larson has determined a nomograph (a graphical calculating Larson’s nomograph can be used as follows: the vertical line on the left-hand side is. From the Larson nomogram, the binomial plan satisfying these specifications is n1⁄, c1⁄ Using the Lieberman and Owen () tables for D1 1⁄(20).

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Latson curve represents the acceptance number c for the plan. A periodic audit to verify that conditions have not changed is a recommended practice when products are not checked on a routine basis.

Larson Nomogram

The left or vertical side of the L coincides with the probability of acceptance on the Thorndike chart. The letter e represents the value of the base of the natural logarithm system.

By using this site, you agree to the Terms of Use and Privacy Policy. There are some minor differences. The random check is used to verify that the process is in control and to report the product quality level. Draw a line from the AQL. The hypergeometric takes into consideration that each sample taken affects the probability associated with the next sample.

This is because they are easier to administer and implement than the other plans and they are very effective.

If the process has been controlled satisfactorily, the product would be accepted and passed on to the next organization or customer. The inside horizontal scale on the L must be lined up with b and a is to coincide with 1 – a on the vertical larsln. The nomograph is used for fraction defective sampling plans. The most common values to use for a and b are. The acceptance number is the maximum allowable defects or defective parts in a sample for the lot to be accepted.


If the number of defects or defectives in the sample exceed the acceptance nonogramm c or ANthe entire lot nomogram, rejected.

The lot will either be accepted rejected or another sample will be taken. In addition, one hundred percent checking cannot be used when a destructive test is made.

They will be provided separately if you have the computer based version of QReview. One hundred percent checking is a sorting operation to separate good product from defective product. Public domain Public domain false false.

An OC curve is developed by determining the probability of acceptance for several values of incoming quality. For products grouped into lots, the entire lot is accepted or rejected. The letter p is the incoming quality level AIQ and P a is the probability of acceptance. Two parameters are specified in a continuous sampling plan. It is a nomograph of the cumulative Poisson probability distribution. The sampling risks are not known, so this method will not guarantee that the outgoing quality will be at an acceptable level.

The AOQL is approximately. The required quality levels determine the acceptance, rejection, and continue sampling regions on the chart.

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The first is the frequency of checking f and the second is the clearing number i. Accepted and screened rejected lots are sent to their destination.

Accepted lots and screened rejected lots are sent to their destination. The L is moved across the chart until one of the acceptance number curves goes through both the a value on the inside vertical scale and the R value on the inside horizontal scale.

Each sampling plan has a unique OC curve. The inspection accuracy is not achieved for small lots and too much time and effort may be spent on large lots. Selecting product for appraising quality characteristics can be done by a number of different methods. This file is ineligible for copyright and therefore in the public domain because it consists entirely of information that is common property and contains no original authorship.


The binomial is used extensively in the construction of sampling plans. Summary [ edit ] Description Larson. Sampling plans are hypothesis tests regarding product that has been submitted for an appraisal and subsequent acceptance or rejection.

The Thorndike chart, which will be discussed later, is a valuable aid in the construction of sampling plans using the Poisson distribution. A quality report is issued and the manufacturing organization nomogrxmm determine what action is to be taken if the material is not acceptable. An easy way to find the sample size and acceptance number is to use a the binomial nomograph or the cumulative Poisson nomograph called the Thorndike chart.

If the number of defects or defectives in the sample do not exceed the acceptance number, the entire lot is accepted. If the process or quality controls laraon broken down, the sampling procedures will prevent defective products from going any farther. A first sample of size n 1 is taken.

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At this time, one out of X shall be inspected. If the number of defects or defectives in the first sample are more than c 1 but less than or equal to c 2a second sample n 2 is selected and inspected.

The chart shows the inspector what decision to make after each sample is inspected. If the sample size is of sufficient size to determine the quality level and a decision can be reached as to accept or reject the lot, then further sampling would not be warranted. Acceptance sampling based on probability is the most widely used sampling technique throughout industry. The no,ogramm of this type nomogramm sampling plan is that a decision could be made based on a relatively small sample.