Meaning
This specific part of the international standard defines an attribute sampling system indexed by the acceptance quality limit for the inspection of discrete lots. When iso 2859-1 sampling is employed, the primary objective is to maintain a high probability that the majority of lots accepted will meet the specified quality level. It provides the tables and procedures for determining sample sizes and acceptance criteria based on the quantity of units in a batch.
This part focuses on the protection of the consumer by limiting the risk of accepting poor quality shipments. It is the most widely used component of the sampling system for battery cell procurement and incoming quality control. The standard applies when the units of product are inspected for compliance with a set of requirements.
Attribute Protocol
The inspection focuses on binary characteristics where each unit is classified as either conforming or nonconforming based on specific criteria. During iso 2859-1 sampling, technicians look for defects such as electrolyte leaks, incorrect dimensions or failed electrical tests. Each defect is categorized by its severity, ranging from minor issues to critical safety failures.
The standard provides different acceptance levels for each category to ensure that safety critical components are held to a higher standard. This method does not measure the degree of variation in a cell but rather whether it falls within the allowed tolerance. Such a pass or fail approach simplifies the inspection process for large volumes of product.
It allows for rapid decision making on the factory floor without the need for complex data analysis.
Acceptance Logic
The system uses a set of master tables to link the lot size to a code letter which then dictates the required sample size. When iso 2859-1 sampling is performed, the technician finds the intersection of the code letter and the chosen acceptance quality limit to find the pass number. If the number of defects found in the sample is less than or equal to this value, the lot is accepted.
If the count is higher, the lot is rejected and must be returned to the supplier or fully screened. This logic provides a clear and objective threshold for quality that both the buyer and seller can agree upon. It eliminates the ambiguity often associated with manual inspections and subjective quality assessments.
These protocols are foundational to the legal and technical agreements between cell manufacturers and automotive companies.
The Switching Rule
A unique feature of this system is the set of procedures for changing the severity of the inspection based on the recent quality history. If iso 2859-1 sampling shows a consistent run of high quality batches, the inspection level may be reduced to lower the testing burden. This transition reduces the number of samples required while maintaining a statistically valid oversight.
However, if a lot is rejected or the quality begins to fluctuate, the system mandates a move to tightened inspection. This increased scrutiny requires more samples and has stricter acceptance criteria to ensure that the supplier regains control of the process. If a supplier fails to improve under tightened inspection, the standard recommends a total halt to the acceptance of lots.
This mechanism provides a powerful incentive for manufacturers to maintain high standards throughout the production lifecycle.
