External suppliers according to ISO 9001.

The supply chain of the product or service provided to the customer comprises different types of external suppliers: suppliers providing products and/or services to be incorporated into those provided by the organization, suppliers providing products and/or services directly to the customer on behalf of the organization (outsourcing), and suppliers providing a process or part of a process.
According to the standard, an organization must establish and apply criteria for selection, evaluation, performance monitoring and re-evaluation of external suppliers to ensure that processes, products, and services externally supplied comply with the requirements.
Therefore, it is necessary to define criteria and metrics for external suppliers’ evaluation taking into account their importance and impact on the quality of the product and/or service provided to the customer. Also, external suppliers should be evaluated from time to time to ensure compliance with the organization’s requirements and expectations.
It is also important to define a process for cases where the external supplier does not meet the acceptable criteria. The organization must have a strategy to replace a particular supplier that does not meet the established requirements, following the criteria outlined by the standard, and considering risk-based thinking.