Introduction
Manufacturing firms which deal with products that are made-to-order, fall under the category of intermittent production systems.Intermittent production systems are geared to produce in batches or small lots.These systems may be of two types depending on the length of the manufacturing cycle time.These are short cycle job shops and long cycle job shops. The job shops have also been classified as machine limited shops and labour limited shops.These firms typically do not hold finished goods inventory. After the customer order is received, design and manufacturing activities will be started and the lead time required to complete the types of jobs is high. Typically made-to-order and engineered-to-order products fall in this category. These types of production environments are characterised by functional layout of the equipment, and high flexibility of the production facilities to cater for a wide range of products. Each product is unique in terms of design, manufacturing and technological requirement and precedence constraints. The processing times are highly uncertain. The high level of uncertainty, with respect to routeings and processing times and uncertainty of customer orders, makes the production planning and control problem a difficult one.Normally these types of organisations are capital intensive. Typically the long lead time manufacturing systems deal with heavy
engineering, make-to-order type and engineered-to-order type of products.In all the above cases it is very difficult to predict the customer requirements and specifications, so keeping inventory is not possible. All the above reasons make the management of long lead time manufacturing systems a more complicated problem.