About Lean Manufacturing and Continuous Improvement
Lean manufacturing or lean production, which is often known simply as "Lean", is a production practice that considers the expenditure of resources for any goal other than the creation of value for the end customer to be wasteful, and thus a target for elimination. Working from the perspective of the customer who consumes a product or service, "value" is defined as any action or process that a customer would be willing to pay for. Basically, lean is centered around creating more value with less work.
Lean principles come from the Japanese manufacturing industry. For many, Lean is the set of "tools" that assist in the identification and steady elimination of waste (muda). As waste is eliminated quality improves while production time and cost are reduced.
There is a second approach to Lean Manufacturing called Toyota Production System(TPS), in which the focus is upon improving the "flow" or smoothness of work, thereby steadily eliminating mura ("unevenness") through the system and not upon 'waste reduction' per se. The difference between these two approaches is not the goal itself, but rather the prime approach to achieving it. The implementation of smooth flow exposes quality problems that already existed, and thus waste reduction naturally happens as a consequence. The advantage claimed for this approach is that it naturally takes a system-wide perspective, whereas a waste focus sometimes wrongly assumes this perspective.
Both Lean and TPS can be seen as a loosely connected set of potentially competing principles whose goal is cost reduction by the elimination of waste. These principles include: Pull Processing, Perfect First-time Quality, waste minimization, continuous improvement, flexibility, building and maintaining a long term relationship with suppliers, Autonomation (employs automatic and semi-automatic processes to reduce physical and mental load on the workers), load leveling, production flow and visual control. The disconnected nature of some of these principles perhaps springs from the fact that the TPS has grown pragmatically since 1948 as it responded to the problems it saw within its own production facilities. Thus what one sees today is the result of a 'need' driven learning to improve where each step has built on previous ideas and not something based upon a theoretical framework.
Toyota's view is that the main method of Lean is not the tools, but the reduction of three types of waste: muda ("non-value-adding work"), muri ("overburden"), and mura ("unevenness"), to expose problems systematically and to use the tools where the ideal cannot be achieved. From this perspective, the tools are workarounds adapted to different situations, which explains any apparent incoherence of the principles above.
The four goals of Lean manufacturing systems are to:
Improve quality: 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:
1).Overproduction (occurs when production should have stopped)
2).Waiting (periods of inactivity)
3).Transport (unnecessary movement of materials)
4).Extra Processing (rework and reprocessing)
5).Inventory (excess inventory not directly required for current orders)
6).Motion (extra steps taken by employees because of inefficient layout)
7).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 because of storage needs.
Steps to achieve lean systems
The following steps should be implemented to create the ideal lean manufacturing system:
1.Design a simple manufacturing system
2.Recognize that there is always room for improvement
3.Continuously improve the lean manufacturing system design
Design a 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
•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”. 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.
A set of performance metrics which is considered to fit well in a Lean environment is overall equipment effectiveness, or OEE.