Generally, the purchasing department’s goals are similar to those of anyone who buys something: Get the best possible quality of all supplies, services and equipment at the lowest cost. Most often, the purchasing department is that part of the procurement section that handles the supply chain process. To ensure quality and to prevent unethical practices, purchasing is usually separate from receiving and accounts payable.
Purchasing departments have changed over time. Historically, they issued purchase orders for all supplies, services, equipment and raw materials, but to save costs they began to put in place "master" agreements for repetitive orders, and they streamlined other routine tasks. This led to a larger role for purchasing departments as strategic sourcing managers who are concerned with purchasing large capital equipment, bidding processes and negotiating with suppliers.
Today, purchasing departments often dominate supply chain management. Typically, they help other departments identify their needs, manage the requisition process and source competitive prices, and generally act as controllers to ensure adherence to budgets.