Sample, SPC (SAP Library - Quality Planning)

Sample, SPC

This subsection describes how to implement sampling procedures, sampling schemes, dynamic modification rules, sample-drawing procedures and control charts.

Samples in the R/3 System

The sampling procedure is stored in the inspection plan for the inspection characteristic, or in the material for the inspection type. The sampling procedure determines the when an inspection lot is ready for processing.
The system takes the current quality level into consideration, together with a dynamic modification rule that has also been defined when it determines the sampling plan. The quality level determines the inspection stage or skip stage for subsequent inspections, based on the inspection history.
If the sample size is to be controlled based on the lot size, the sampling procedures reference sampling schemes and the inspection severities that form the basis of the sampling schemes are assigned to the inspection stages that have been defined in the dynamic modification rule.

In the R/3 System, the sampling procedure defines the sampling type and the valuation mode . If the sampling procedure is to be used to retrieve data for quality control charts , it also specifies the control chart type .

While the sampling procedure determines the size and the valuation of the sample , the sample-drawing procedure controls the type and number of the physical samples to be taken.

Standard Settings

Sampling Schemes

The standard system contains ready-to-use sampling schemes that conform to:

DIN ISO 2859-1 for qualitative inspections

DIN ISO 3951 for quantitative inspections

The data from the DIN standards has been reproduced with the permission of the German Institute of Standards). This data corresponds to the current version of the ISO-DIN standards.
(<Date of current release>, SAP AG)

You may copy the sampling schemes from client 000 into the current client and use them as a function of the R/3 System. SAP, however, accepts no liability for the validity of the data.

The R/3 System uses the following nomenclature for the 'A'B'C' description in the sampling schemes:

'A' (description of norm) : 1 = ISO 3951 / 2 = ISO 2859

'B' (description of method): 1 = s-method or single sample

'C' (description of level) : 1 / 2 / 3 / 4 = S-1 / 5 = S-2 / ...

Sampling Procedures

The standard system contains complete sampling procedures, which use the sampling schemes mentioned above.
The R/3 System uses the following nomenclature for the eight-digit description 'ABCDEFGH' for the sampling procedure:

'A' sample type : S = use sampling scheme

'B' valuation mode:
1 = Attribute inspection using the number of nonconforming units
2 = Attribute inspection using the number of defects
3 = Variable inspection according to the double-sided s method

4 = Variable inspection according to the single-sided s method

'CDE' sampling scheme

'F' number of samples: n = n-fold sample

'G' preferred inspection severity

'H' AQL: A = 0.01; B = 0.015; C = 0.025; D = 0.04; E = 0.065;
F = 0.1; G = 0.15; H = 0.25; I = 0.4; J = 0.67
K = 1.0; L = 1.5; M = 2.5; N = 4.0; O = 6.5
P = 10; Q = 15; R = 25; S = 40; T = 65;
U = 100; V = 150; W = 250; X = 400; Y = 650;
Z = 1000

Dynamic Modification Rules

The standard system contains the following dynamic modification rules that can be used in connnection with the sampling procedures mentioned above:

S01 dynamic modification of the inspection severity according to
ISO 2859-1, section 9.3 (no limiting values according to section 9.3.3b)

S02 dynamic modification with skip according to ISO 2859-3
(no limiting values according to table 1 and table 2, as well as
without cubing calculation according to appendix B)

Recommendation

Do not maintain the data until you have familiarized yourself with the terms used in the above text.

The standards may have changed since the date of the current release and errors may have occurred as a result of maintaining and importing the data. For this reason, make sure the data is valid before you use it productively!

In the chapter Basic Settings,

Setting up clients you are instructed how to transport the sampling data contained in the standard client 000 to the current clients.

Activities

1. Develop a sampling concept
Decide on a basic approach; do you want to retain the procedures used in your company or do you want to re-evaluate the objectives of the sampling procedures and possibly redefine them? You can implement most of the common sampling procedures in the R/3 QM component. With the support provided by the R/3 QM component, however, you have additional options, especially for dynamic modification. If you want to re-evaluate your philosophy with respect to the sampling procedures, ask yourself the following questions:

a) What purpose should the sampling inspection serve?

b) Which sampling procedure (sampling type and valuation mode) is best for this purpose?

c) Are the sampling procedures currently being used supported by sampling schemes?

d) Can the inspection scope be optimized through dynamic modification?

e) Are control charts to be displayed or used for valuation purposes?

f) Is the drawing of physical samples to be defined?

2. Maintain the settings and master data in the proper sequence:

a) Set the sampling types .

b) Set the valuation modes .

c) Maintain the sampling schemes (create master records).
Provided you want to use sampling schemes in the sampling procedures that do not already exist in the standard system.
If you want to use
inspection severities other than the ones set in the standard system, you must first define them.

a) Define the dynamic modification rules (create master records).

b) Maintain the sampling procedures (create master records).

c) Maintain the allowed combinations of sampling procedures and dynamic modification rules.
When you maintain the sampling procedures and dynamic modification rules, the system will prompt you to maintain these combinations. You can ignore this initially. If you only need a few dynamic modification rules, but many sampling procedures, it may be convenient to maintain the dynamic modification rules first and then assign these rules immediately when you maintain the sampling procedures.

d) Maintain Sample-Drawing Procedures
If the number of samples is to be calculated dependent on the lot container, you need corresponding

units of measure for the container.
Settings for

sample management are contained in the Quality Inspection section.

Additional Information

You can implement the most common, internationally standardized sampling systems (sampling types, valuation modes, dynamic modification rules) in the QM component without having to make any modifications. For example, this applies to:

ISO 3951, s-method

ISO 2859, part 1; valuation according to number of defects or number of nonconforming units, but without multiple samples or limiting values.

ISO 2859, part 3; skip lot with inspection frequencies that can be predefined

The QM component handles the input parameters for the sampling procedures ( inspection level, inspection severity and AQL) in a special way:

In the QM component, inspection levels are neither stored in the sampling schemes nor in the sampling procedures. This means if you want to work with several inspection levels, you must store separate master records for the sampling scheme and sampling procedure for each level.

In the QM component, the inspection stage and AQL are input parameters for the sampling scheme. This means that you can maintain the sampling plans for several inspection severities and AQLs in one sampling scheme master record.

With the help of the two input parameters inspection severity and AQL, the sampling procedure selects the appropriate sampling plan from the sampling scheme based on the lot size. Depending on whether or not dynamic modification is specified, the sampling procedure proceeds differently:

If no dynamic modification of the inspection severity takes place, the inspection severity and AQL are taken from the sampling procedure. This means there is one sampling procedure master record for each inspection severity and AQL.

If dynamic modification of the inspection severity takes place, only the AQL is taken from the sampling procedure. The sampling procedure takes the inspection severity specified in the current quality level. You must maintain a sampling procedure master record for each AQL.

The sampling procedure and the dynamic modification rule are both contained in the inspection plan. To make sure the inspection severities in the sampling scheme (which supports the sampling procedure) fit the inspection severities in the dynamic modification rule, you must define the allowed combinations of sampling procedures and dynamic modification rules.
You must decide which combinations of sampling procedures and dynamic modification rules are compatible with each other and can be used together in an inspection plan. This applies only to sampling procedures with sampling schemes; sampling procedures without sampling schemes can be combined with any dynamic modification rules in the inspection plan.
The system allows you to assign a dynamic modification rule only if all of the inspection severities in the sampling scheme (associated with the sampling procedure) have been maintained, which have been assigned an inspection stage in the dynamic modification rule. This means: for the AQL defined in the sampling procedure, the sampling scheme contains sampling plans for all inspection stages supported by the dynamic modification rule. Skip stages are not assigned an inspection severity.