The ideal product is one that meets or exceeds customer expectations, makes the best use of material, and can be manufactured with a minimum of waste. As well as satisfying the customer, the product’s design determines both the basic manufacturing processes that have to be used and the cost and quality of the product. The product should be designed so it can be made by the most productive process with the smallest number of operations, motions, and parts and included all of the features that are important to the customer.
Waste Caused in Manufacturing
The following seven important sources of waste in manufacturing have been identified. The first relate to the manufacturing system and the last three to the operation and management of the systems”
- The Process: The best process is the one that has the capability to consistently make the product with an absolute minimum of scrap, in the quantities needed, and with the least cost added. Waste, or cost, is added to the process if the wrong type or size or machine is used, if the process is not being operated correctly, or if the wrong tools and fixtures are used.
- Method: Waste is added it the methods of performing tasks by the operators cause wasted movements, time, or effort. Activities that do not add value to the product should be eliminated. Searching for tools, walking, or unnecessary motions are all examples of waste.
- Movement: Moving and storing components adds cost but not value. For example, goods received may be stored and then issued to production. This requires labor to put away, find, and deliver to production. Records must be kept in a storage system maintained. Poorly planned layouts may make it necessary to move products over long distances, thus increasing the movement cost and possibly storage and record-keeping costs.
- Product Defects: Defects interrupt the smooth flow of work. If the scrap is not identified, the next workstation receiving it will waste time trying to use the defective parts or waiting for good material. Schedules must be adjusted. If the next step is the customer, then the cost may be even higher. Sorting out or reworking defects are also waste.
- Waiting Time: There are two kinds of waiting time: that of the operator and that of material. If the operator has no productive work to do or there are delays in getting material or instructions, there will be waste. Ideally, material passes from one work center to the next and is processed without waiting in queue.
- Overproduction: Overproduction is producing products beyond those needed for immediate use. When this occurs, raw material and labor are consumed for parts not needed, resulting in unnecessary inventories. Considering the cost of carrying inventory, this can be very expensive. Overproduction causes extra handling of material, extra planning and control effort, and quality problems. Because of the extra inventory and work-in-progress, overproduction adds confusion, tends to bury problems in inventory, and often leads to producing components that are not needed instead of those that are. Overproduction in not necessary as long as market demand is met. Machines and operators do not always need to be fully utilized.
- Inventory: Inventory costs money to carry, and excess inventory adds extra costs to the product. However, there are other costs in carrying excess inventory.
To remain competitive, a manufacturing organization must produce better products at lower cost while responding quickly to the marketplace.
Courtsey: Inventory Management Book from Pearson press