Technical article
Supplier audits for preventive quality assurance
Munich – Manufacturing companies are constantly exposed to the risk that irregularities and failures on the part of their suppliers could disrupt their own production processes—leading to delays or even production stoppages—as well as quality defects. Against this backdrop, every manufacturing company should take preventive measures to ensure the quality and delivery reliability of its suppliers and to minimize risks. An important tool for this is the regular auditing of suppliers’ processes and products by the manufacturing company.
It all comes down to making the right choice
Supplier audits can be conducted either on-site at the supplier’s premises by the manufacturing company or, on behalf of the manufacturing company, through a self-assessment by the supplier. A supplier audit conducted on-site by an auditor is particularly time-consuming and resource-intensive. Given the resources required, significant emphasis is therefore placed on selecting the scope of the audit and deciding on the type of audit. The following questions must be answered in advance: How many audits are necessary? At what intervals should the audits take place? For which suppliers is an on-site visit appropriate, and where can a self-assessment by the supplier be conducted?
Various indicators can be used in this context. For example, suppliers of critical components should be evaluated during an on-site audit. Other indicators for an on-site visit may include, for example, previous quality defects in delivered parts, past delivery delays, or large order volumes. For less critical components, however, the supplier may conduct a self-assessment, which is verified as needed through random spot checks by the manufacturing company.
Conducting supplier audits
Every supplier should be contractually obligated to audit each component (or component family) at regular intervals. Whether this is conducted by an auditor or the supplier itself, the process always begins with a self-assessment by the supplier. In this context, the supplier evaluates various issues related to product requirements, production planning, measurement and validation, audits, objectives and control loops, sub-supplier management, the shop floor, maintenance, and test equipment.
If the supplier conducts a self-assessment, the manufacturing company may perform a random check to verify the plausibility of the results. For components that are subject to special scrutiny, the self-assessment is followed by an on-site visit by an auditor from the manufacturing company. During a one- to two-day audit, the issues are reviewed and validated once again together with the supplier.
Identification and Mitigation of Risks
The purpose of the audits is to identify potential risks. In the event of nonconformities, corrective actions are formulated and their implementation is agreed upon with the supplier. To ensure that the risk is eliminated on a long-term basis, the auditor verifies that the actions have been implemented. The effectiveness of these measures can then be measured using quality metrics, such as the number of defective parts or rework minutes.
The audit results can also be used as an index for evaluating suppliers and, for example, serve as a key metric in the supplier selection process.
