Network Capacity

Production Model

Manufacturing capacity is affected by the slowest rate of any piece of equipment in the manufacturing process. Many times, the same equipment is used for making multiple products. When this is the case, it is called block-operating and a series of products (a campaign) is made before the first product is made again.

All time spent cleaning and retooling the equipment for the next product to be made is called changeover time. The aggregate of all changeover time is lost capacity when no product is made. Therefore, the more products that are made on the same equipment, each additional product erodes the annual capacity of the entire production facility due to the additional changeovers. Different products can have different run rates. The campaign time is the aggregate time of all changeovers plus the time to make every product. The order in which the products are made is called the sequence. Cleanout and setup between individual products can vary in time depending on the nature of the equipment and the products themselves. Therefore, there is usually a preferred sequence to minimize the changeover time.

Some software attempts to explicitly model all above issues. Our software approximates the capacity impact. There is a tradeoff between model maintenance and model granularity. The point is to get to 80% of the solution with 30% of the effort. The approximation can be compensated for by adjusting the network safety stock.