Industry has traditionally maintained organizational structures that have resulted in limited cross-functional interaction and cross-boundary communication. During the 1990s, the need for closer relationships between functions became clear. Purchasing must communicate closely with other functional groups, which are purchasing’s internal customers. These are sometimes called stakeholders, in that they have a significant stake in the effectiveness of purchasing performance!
If a supplier’s components are defective and causing problems for manufacturing, then purchasing must work closely with the supplier to improve its quality. Similarly, marketing may spend a great deal on advertising and promotion, so purchasing must ensure that the pricing is competitive and that service-level agreements are being met. In order to achieve this objective, purchasing must develop positive relation ships and interact closely with other functional groups, including marketing, manufacturing, engineering, technology, and finance.
Source: Purchasing and Supply Chain Management. (Monczka, Handfield, Giunipero, Patterson)