Lean manufacturing systems are aimed towards attaining the shortest cycle time by eliminating waste. Instead of allotting resources that would be required for future production, lean manufacturing systems focus on decreasing system response time so that the production system is able to immediately change and adapt to market demands. Lean systems are customer
driven, as products are produced only for a specific customer instead of being added to inventory
. This is done using One Piece Flow
In One Piece Flow, a part is put through the first process and immediately handed off to the second process. The second process is completed on the part and it is given to the third process, which is then completed and so on. The goal of this type of process is that there is no batch
or build-up of parts at any given stage in the process.
The four goals of Lean manufacturing systems are to:
- Improve quality: In order to stay competitive in today’s marketplace, a company must understand its customers' wants and needs and design processes to meet their expectations and requirements.
- Eliminate waste: Waste is any activity that consumes time, resources, or space but does not add any value to the product or service. There are seven types of waste:
- Overproduction (occurs when production should have stopped)
- Waiting (periods of inactivity)
- Transport (unnecessary movement of materials)
- Extra Processing (rework and reprocessing)
- Inventory (excess inventory not directly required for current orders)
- Motion (extra steps taken by employees due to inefficient layout)
- Defects (do not conform to specifications or expectations)
- Reduce time: Reducing the time it takes to finish an activity from start to finish is one of the most effective ways to eliminate waste and lower costs.
- Reduce total costs: To minimize cost, a company must produce only to customer demand. Overproduction increases a company’s inventory costs due to storage needs.
Steps to Achieve Lean Systems
The following steps should be implemented in order to create the ideal lean manufacturing
- Design a simple manufacturing system
- Recognize there is always room for improvements
- Continuously improve the lean manufacturing system design
Design Simple Manufacturing System
A fundamental principle of lean manufacturing is demand-based flow manufacturing. In this type of production setting, inventory is only pulled through each production center when it is needed to meet a customer’s order. The benefits of this goal include: :
- decreased cycle time
- less inventory
- increased productivity
- increased capital equipment utilization
There is Always Room for Improvement
The core of lean is founded on the concept of continuous product and process improvement and the elimination of non-value added activities. “The Value adding activities are simply only those things the customer is willing to pay for, everything else is waste, and should be eliminated, simplified, reduced, or integrated”(Rizzardo, 2003). Improving the flow of material through new ideal system layouts at the customer's required rate would reduce waste in material movement and inventory.
A continuous improvement mindset is essential to reach a company's goals. The term "continuous improvement" means incremental improvement of products, processes, or services over time, with the goal of reducing waste to improve workplace functionality, customer service, or product performance (Suzaki, 1987).
A set of performance metrics which is considered to fit well in a Lean environment is Overall Equipment Effectiveness
, or OEE.
Books on Lean Manufacturing
MacInnes, Richard L. (2002) The Lean Enterprise Memory Jogger