An initial sample is usually subject to complete testing in order to prevent defects already from the beginning of series production and/or to check whether the limit values and tolerances agreed by the purchaser and the manufacturer have been complied with.
The procedure for initial sample testing is specified in the quality assurance agreement together with the supplier. If there already is a standardized report form, the supplier enters the target and actual values with the deviations of the parts tested. The inspector can then request or carry out further testing. For the inspector, initial sample testing is the first opportunity to inspect the quality of the castings.
According to another common definition, initial samples are those products completely manufactured by means of the equipment, resources and processes used for series production under series production conditions. Sampling by means of initial samples is then referred to as initial sample testing. The sampling carried out for the purpose of production process and product approval has to use and be based on initial samples.
A positive evaluation of the initial sample (incl. all the required, comprehensive documentation) by the customer usually results in the approval of the supplier’s series production processes.
Essential characteristics of initial sampling:
An essential characteristic of initial sample testing included in both definitions is the first-time production of the goods to be sampled under realistic series production conditions. However, both definitions do not expressly specify whether the production process itself needs to be subject to a process capability test or is to be inspected by means of any other test method.
The second essential characteristic of initial sample testing also included in both definitions is the subsequent testing of the produced initial sample with respect to the casting properties requested by and agreed with the purchaser. Here, too, the definition is unspecific as to the test method.
Differences in the interpretation of both definitions:
The first definition is based on the assumption that the initial sample testing is solely carried out on the basis of a quality assurance agreement which is not necessarily the case in practice. In fact, the obligation to perform initial sample testing can also be the subject of another contractual agreement (e.g. a purchase contract, delivery contract, master supply agreement or non-disclosure agreement).
The second definition contains two additional essential characteristics of initial sample testing, namely the requirement to provide documentation and approval of the supplier by the customer upon successful initial sample testing.
(For further information, see, e.g., “Initial sampling in the automotive industry” under Sampling.)