Implementing ANSI Z1.4 C=0 Sampling with Quality Inspector

ANSI Z1.4 C=0 sampling is supported in Quality Inspector through the AQL sampling plan configuration.

In this context, “C” does not refer to the sample code letter used to determine sample sizes. Instead, it refers to the acceptance number in the ANSI Z1.4 acceptance formula:

Accept the lot if the number of defects ≤ C, and reject the lot if the number of defects > C.

When C = 0, no defective samples are allowed.

Any sample that fails causes the entire lot to be rejected.

To implement C=0 in Quality Inspector there are three fundamental requirements:

• Set the Acceptance Point to 0.
• Set the Rejection Point to 1.
• Set the Reject Grade.

The net effect is that any failed sample causes an AQL failure and applies the configured reject grade.

This approach is commonly used in industries that require stricter quality control and where no defective units are considered acceptable.

Configure the Sampling Plan

Quality Inspector determines the sampling requirements by combining:

• Inspection Level (I, II, III, S1-S4)
• AQL Level
• Lot Size

These values determine the sample code letter and recommended sample size.

On the Quality Inspector Sample Size Configuration, verify that the sample size code mappings exist. These records are normally installed by the Quality Inspector Setup Wizard.

On the Quality Inspector AQL Sampling Plan, configure the appropriate code letter and AQL combination so that:

• Acceptance (Ac) Point = 0
• Rejection (Re) Point = 1
• Reject Grade = FAIL (or your preferred failure grade)

A rejection point of 1 means that as soon as one sample fails, the lot fails.

When a “Reject Grade” is defined it will cause the line to immediately fail as soon as the failure criteria is reached (Rejection Point of 1).

Configure the Template

On the Quality Inspection Template, specify:

• The default Inspection Level
• The default AQL Level

These values determine which sampling plan will be used when a test is created.

Example

Suppose:

• Lot size = 2 to 8 pieces
• Inspection Level = II
• AQL = 0.07

The sample size configuration may produce code letter A, which in turn results in:

• Sample Size = 2
• Acceptance Point = 0
• Rejection Point = 1
• Reject Grade = FAIL

When the inspection is performed:

• If both samples pass, the lot passes.
• If either sample fails, the lot immediately fails.

Supporting All 16 ANSI Z1.4 AQL Levels

Quality Inspector allows you to define your own AQL values. The standard ANSI Z1.4 levels, such as:

0.04, 0.065, 0.10, 0.15, 0.25, 0.40, 0.65, 1.0, 1.5, 2.5, 4.0, 6.5, 10.0, and 15.0

can all be configured by modifying the AQL sampling plan records.

Practical Considerations Should You Configure AQL with C=0?

In some situations it is worth considering whether AQL is necessary at all to configure in the system, since C=0 means any failed sample causes the entire lot to fail, this can often be accomplished with a simpler process.

Using AQL with C=0 is most beneficial when one or more of the following are true:

• Sample size should still be automatically determined from lot size and inspection level.
• You need to support normal, tightened, or reduced inspection levels.
• You need to retain failed samples for auditing or regulatory compliance.
• You want operators to complete all samples even after the test has already failed.
• Individual sample values need to be analyzed historically over time.
• Individual measurements must be recorded for traceability or other business requirements.

If none of these requirements exist, it may be simpler to avoid AQL entirely and instead use the sample size directly, or configure fields to fail immediately by using the First Failed Value sample summary method.

Supporting Multiple Standards with AQL Grouping Code

The examples in this article assume that C=0 is being used throughout the entire Business Central company.

Quality Inspector supports multiple sampling standards in the same company by using AQL Grouping Code.

If only some templates or processes require C=0 while others use different AQL standards, create a separate AQL Grouping Code and configure the C=0 sampling plans under that grouping code.

To do this:

1. Show the AQL Grouping Code field on the AQL configuration pages.
2. Create a new grouping code for the C=0 standard.
3. Configure the sample size and AQL plan records under that grouping code.
4. Assign the grouping code to the appropriate templates.

Using different grouping codes allows multiple sampling standards to coexist within the same Business Central company, if there are different sampling standards required for different industries, different major customers, etc.

Important Notes

The Inspection Level (I, II, III, S1-S4) should not be confused with the Acceptance Quality Level (AQL) values.

C=0 does not mean the sample size is always one. It means that the acceptance number is zero and the rejection number is one. The actual sample size is still determined by the lot size, inspection level, and AQL level.

If you are not using AQL sampling, a similar effect can be achieved by configuring the Quality Inspection Field with a sample summary method of First Failed Value, which causes the inspection to fail immediately when the first failing sample is encountered.

Configuring C=0

Step 1: Open the AQL Sampling Plan

1. Navigate to Quality Inspector Setup.
2. Choose AQL Sample Plan Configurations.
3. Open the Quality Inspector AQL Sampling Plan page.

Step 2: Select the Configurations to Modify

Optionally filter to:

• Specific sample size code letters.
• Specific inspection levels.
• Specific AQL values.

If C=0 should apply to every scenario, do not apply filters.

Step 3: Configure the Acceptance and Rejection Limits

For each row:

• Set Acceptance Point = 0
• Set Rejection Point = 1
• Set Reject Grade

If using the default grades supplied with Quality Inspector, set Reject Grade = FAIL.

For example:

Code	Sample Size	Inspection Level	AQL	Acceptance Point	Rejection Point	Reject Grade
A	2	General Level II	0.065	0	1	FAIL
A	2	General Level II	0.10	0	1	FAIL
A	2	General Level II	0.15	0	1	FAIL
A	2	General Level II	0.25	0	1	FAIL
A	2	General Level II	0.40	0	1	FAIL
A	2	General Level II	0.65	0	1	FAIL
A	2	General Level II	1.0	0	1	FAIL
A	2	General Level II	1.5	0	1	FAIL
A	2	General Level II	2.5	0	1	FAIL
A	2	General Level II	4.0	0	1	FAIL
A	2	General Level II	6.5	0	1	FAIL
A	2	General Level II	10.0	0	1	FAIL
A	2	General Level II	15.0	0	1	FAIL

Example Usage

Assuming:

• The AQL configuration has already been completed.
• A Quality Inspection Template has been configured to use AQL.
• At least one field accepts multiple samples.

Create a test.

Notice that:

• The Acceptance Point is 0.
• The Rejection Point is 1.

Record sample values.

As soon as the first sample reaches a failing condition:

• The sample fails.
• The AQL line fails.
• The test receives the configured reject grade.

This occurs even if some samples remain incomplete.

How C=0 Works

The Rejection Point determines how many failed samples are required before the AQL result is considered a failure.

By setting:

• Acceptance Point = 0
• Rejection Point = 1

Quality Inspector is effectively configured so that:

• Zero failed samples are acceptable.
• One or more failed samples causes an AQL failure.

The configured Reject Grade is then applied to the test.

The actual sample size is still determined by the sample size configuration, inspection level, and AQL level. C=0 only changes the acceptance criteria; it does not mean the sample size is always one.