This text is from the second edition of ISO 9001, The Standard Companion. It is based on the now obsolete 1987 version of the ISO 9001 Standard. The third edition, based on the current 1994 standard, is available from Simply Quality.

4.6 Purchasing

4.6.1 General

Request Exactly What is Needed from Your Suppliers

Make sure that materials or services you order from suppliers are what you specify and need.


The Standard recognizes that a chain is only as strong as its weakest link. Most products are assembled from materials obtained from outside suppliers. To ensure that the materials or services you purchase are suitable, this section extends your Quality System to include the selection of suppliers and the material or services purchased from them.

4.6.2 Assessment of Sub-Contractors

Manage Your Suppliers

Choose suppliers based on their ability to provide products that meet your specification. Establish and use approved suppliers lists based on product quality requirements, as well as a history of the supplier to consistently fulfill these needs. This performance history will give an indication as to whether or not quality management regarding your suppliers is effective. Maintain a written record of your approved suppliers.

The degree of control that you exercise over selection of your suppliers depends on the type of product purchased and the suppliers' previous history of performance.


An effective way to comply with these purchasing requirements is to have your suppliers obtain registration with the applicable ISO 9000 series standard. To evaluate the effectiveness of a supplier, it is useful to consult information that evaluates the quality of your product. Institute procedures for taking corrective action with suppliers when they provide defective material or services. Be prepared, with written procedures, to remove a supplier from your approved list, if he does not comply with the requested corrective actions. Products or services obtained by divisions within your company that are outside your Quality System are treated as if they are provided by an outside supplier and must comply with this provision.

4.6.3 Purchasing Data

Write Clear and Specific Purchase Orders

Clearly describe on purchase orders the product or service being ordered. Include a precise identification of the product; identify or set forth detailed specifications for the product being ordered (these may include requirements for inspection or approval); point out the particular Quality System Standard (e.g., ISO 9001) that your supplier must satisfy for this product.

Review and approve purchase orders based on the above criteria before sending them out.


Where one exists, make reference to a contract or product specification on the purchase order. Require effective review and approval of purchase orders. Consider including the following information: quantity and price, delivery date and location, identification of detailed specifications of type, class, style and grade of product including the specification issue number, performance characteristics, packaging and labeling requirements, product quality data such as inspection certification or control charts, pre-shipment sample requirements, point of ownership transfer, and transportation requirements.

If the supplier is required to comply with the requirements of ISO 9001 in fulfilling the order, say so in the purchase order.

4.6.4 Verification of Purchased Product

Let Your Customer Inspect Materials You Buy

With your prior permission, your customer may verify, either at your supplier's location or at your receiving area, material or services you have purchased conform to specification. And even if your customer carries out such verification, you are still accountable for controlling the quality of material from your supplier and providing an acceptable end product to your customer


There is no way around it. If you buy something to include in your product or service, you are responsible for its quality!

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