The traditional approach to determine material requirements is to monitor inventories constantly; whenever they fall to a predetermined level, a preset order is placed to replenish them. This traditional approach (involving re-order levels and economic order quantity calculations originates in the pre-computer era.

A manufacturing resource planning approach to the management of all the company’s manufacturing resources including inventory, labour and machine capacity.

It seeks to ensure that resources are available just before they are needed by the next stage of production or dispatch. It also seeks to ensure that resources are delivered only when required so that raw material inventory is kept to a minimum.

The technique will not enable managers to track orders through the manufacturing process and will not assist the purchasing and production control departments to move the right amount of material or sub-assemblies at the right time to the right place.

The correct inventory management system relies on the assumption that there is constant demand. An MRP system begins with the setting of a master production schedule specifying both the timing and quantity demanded of each of the finished goods items and then works backwards to determine the resource requirements at each stage of the production process.

It aims to generate an estimation of materials requirements after taking account of the number of employees quality and waste. The TQS model can be used within MRP provided that the major assumption in the TQS model of constant demand applies.