The current push towards lean manufacturing originates from the Toyota Production System which is often referred to as Just In Time (JIT) Production. The Toyota Company became successful after World War 2 when Japanese factory owners adopted a number of American production and quality techniques. The manufacturing techniques of Henry Ford and the Statistical Quality Control ideas of Edwards Deming became the foundation of Toyota’s production process.
Unlike the American automotive industry Toyota encouraged employees to be a part of the production process. The company introduced quality circles which was a group of workers who meet to discuss workplace improvement. Quality circle members make presentations to management with regarding the quality of production.
Toyota developed a set of procedures that reduced the time required for setup and changeovers. Unlike Ford’s production, Toyota developed manufacturing in smaller batches and this required a set of processes that reduced setup and changeover times. The resulting procedure was Single Minute Exchange of Die (SMED). There are seven steps used in the SMED method for changeover, including streamlining the external and internal activities.
The developments made by Toyota were adopted by other Japanese manufacturers but none were as successful. In the 1980’s American companies began to adopt some of the processes developed by Toyota and gave these names such as Continuous Flow Manufacturing (CFM), World Class Manufacturing (WCM) and Stockless Production.
Principles of Lean Manufacturing
The ultimate goal for a company that adopts lean manufacturing processes is to reduce waste. An average company will waste a significant amount of resources. In cases where the manufacturing process is outdated the level of waste can be close to 90%. By adopting lean manufacturing processes the waste can be reduced to around 25-35%. Lean Manufacturing processes can improve -
- Material Handling
- Customer Satisfaction
The benefits in material handling when lean manufacturing procedures are deployed include fewer moves of material, shorter travel distances in the warehouse and simpler picking routes in the warehouse. These also contribute to savings in inventory and improvements in quality.
By using smaller lots, the inbound and outbound queues are smaller. This reduces the inventory required to be in the queue and therefore the inventory level overall.
Smaller lots mean that any quality issues that arise can be dealt with at the time of manufacture. In manufacturing processes with larger lot sizes, quality issues may not be identified until late into the process and can be costly to correct, both in time and resources.
Improvements in material handling, inventory and quality all lead to a more successful manufacturing operation. If items are produced on time and delivered to a customer by the delivery due date, customer satisfaction will increase. The same is true if the items sent to the customer are of a higher quality standard. This will reduce the incidence of repairs, returns and customer complaints.