What is Lean Manufacturing?

Lean Manufacturing concepts

Lean Manufacturing is a type of manufacturing system that aims to eliminate waste in all of its forms. This waste includes activities that add no value to the over all production of a good or service. By eliminating these wastes the company benefits from having fewer expenses and losses of time due to a lack of productivity. The customer benefits from the lean manufacturing system by benefiting from the cost savings that the manufacturer can pass on to the consumer and also by receiving a product that is free from defect or fault, as is the objective of a waste free system.

Where there are other systems that focus on eliminating waste in certain steps of the manufacturing process, Lean Manufacturing is all about tackling the waste problem from a company-wide approach. The objective of the manufacturing company is to create what is called a "value stream." A value stream refers to the continuous flow of products and materials that is not burdened by the starts, stops and delays of dealing with waste. Remember that waste can include not only material overflow but also any activity, step, or process that does not ultimately end in providing the customer with value. Remember, if the customer is not willing to pay for something that you spend time on, then you want to eliminate that part of production in order to maximize your company's profitability.

Lean Manufacturing concepts are obviously appealing to most manufacturing companies however each company has different levels or degrees at which they commit to running a lean operation. Lean Manufacturing is also referred to by a variety of names including the most popular alternative name; the Toyota Production System (TPS). The TPS is all about the systematic elimination of waste and was originally developed by the founder of the Toyota Company.

The role of Henry Ford and Toyota in Lean Manufacturing

Henry Ford is perhaps most famous in the manufacturing world because of his development of the mass assembly manufacturing system. Henry Ford experienced success that was unparalleled in the country at that time. His successes and contributions to making Lean Manufacturing what it is today are attributed to his ability to see efficiency in a way that it had never been seen before. For example, Ford saw true efficiency as constant increase of quality, great increase of pay to the workers, repeated reduction in cost to the consumer. In Ford's autobiography (My Life and Work, 1922), he summarizes what would be known as Lean Manufacturing and wastes with the use of an example involving a farmer:

"I believe that the average farmer puts to a really useful purpose only about 5% of the energy he expends.... Not only is everything done by hand, but seldom is a thought given to a logical arrangement. A farmer doing his chores will walk up and down a rickety ladder a dozen times. He will carry water for years instead of putting in a few lengths of pipe. His whole idea, when there is extra work to do, is to hire extra men. He thinks of putting money into improvements as an expense.... It is waste motion- waste effort- that makes farm prices high and profits low."

It was Ford that first formally conceptualized that habitual actions and poor organization and arrangement in the manufacturing workplace are the sources from which wastes were born. Ford summarizes his whole Lean Manufacturing beliefs in a simple sentence when he says, "As we cut out useless parts and simplify necessary ones, we also cut down the cost of making."

The Toyota company is also credited with the development of many of the manufacturing ideas that later became known as "Lean." When Toyota transitioned from the business of textiles to the manufacturing of motor parts, their CEO saw that a lot of time and resources were wasted in the repairing of casts of poor quality. The pressure to create low cost items was great and overproduction was not an option as there were simply too few customers to market the surpluses to. Through solving these problems and creating schools of thought such as Kaizen, Autonomation, and Jidoka, the themes of the Toyota Company came together and are called the Toyota Production System (TPS).

Types of waste

Naturally in order to eliminate waste it is useful that there be a method for identifying such waste. Toyota assigned a name to non-value work that they call "muda." Muda is only discovered in a manufacturing process once the process has been set in place and put into action. Then it is dealt with until variation in output can no longer be seen. The inconsistencies that care found to be the cause of variation are then fed back into the Lean Manufacturing planning system and re-evaluated for a trial of the next project and corresponding system of production. The process of identifying waste or muda is constantly changing due to the fact that the demands placed on the manufacturing company are ever changing. Whenever demand is changed supply is then affected in order to balance out these effects, improvisation is needed. Naturally, this can lead to downtime and mistakes. However, the process of correction and re-standardizing manufacturing system movement can be relatively quick if wastes can quickly be identified and plans made for the elimination of such wastes.

The seven muda or "deadly wastes" are defined as follows:

1. Waste from overproduction - Overproduction occurs when the manufacturer produces more than what is required by the customer or marketplace. In overproducing a product, the level of production is exceeding the level of demand, thereby generating unnecessary inventory.

2. Waste from transportation - In this context, the term transporting refers to any movement that the product takes part in as part of the production process. Multiple handling or movement of products does not add any value to the product if those movements are not required by the production process.

3. Waste of motion - Waste of motion refers to the time that is wasted by workers, machines, and handling due to the fact that they are working or moving more than is necessary to perform their assigned step in the production line. An example would be searching for tools or parts due to the inappropriate location of these items. Time is wasted in the motion of looking for these tools, when instead the time of the worker should be completely devoted to accomplishing their assigned portion of the production process.

4. Waiting - Time is wasted whenever there is a period of waiting in between steps. For example, a worker waiting for a machine to finish a cycle or leaving their station in order to ask their supervisor a question, reflects an interruption to flow, a waiting period of sorts, and needs to be eliminated.

5. Processing - Tool and product design have a great deal to do with what type of time is necessary or unnecessary to the steps of processing. Combining steps or having workers or equipment perform multiple steps should be done in order to decrease processing time.

6. Inventory - Inventory items are also referred to as products that are still "works in process" or WIP. These inventory items include all components of the product (including the finished piece) that are not being immediately processed. The production of inventory increases the cycle and processing times in production.

7. Defects - Perhaps the most obvious and detrimental of all the forms of waste is the producing of defective products. Even if there is a system in place for the inspecting, scrapping, or repairing of these defective products, their creation is by definition pure waste according to Lean Manufacturing principles. These clear identifications or definition of work that adds no value to the production process are critical. After being identified, they are used to evaluate the current work process and naturally the next step is to make changes to the operating system as it is currently organized. Opportunities may lie dormant if the processing assumptions are left unchallenged. Just in Time manufacturing

The Just in Time manufacturing technique is probably the most recognized and widely used of all the Lean Manufacturing techniques. Just in Time manufacturing gets it name from the process of Lean Manufacturing that it employs in order to reduce wastes. In short, the Just in Time manufacturing technique is to have the "right part at the right place in the right amount at the right time" (this is according to the book "Running Today's Factory"). Just in Time manufacturing focuses on shortening the time it takes to produce on product (also known as the product cycle), decreasing the amount of carried inventory, and streamlining work flow.

Just in Time manufacturing is a very difficult concept for some manufacturers to implement simply because it forces them to cut back on production even if there are prospects for more sales. In the past, the volume of production that a company was able to achieve was a sign of efficiency. This is true only if the volume being produced directly correlates with the immediate demand that the consumer has for that product. Finding the balance between the demand of the customer and the supply that you manufacture is the big challenge, especially when positive occurrences, such as in increase in sales or interest in your company, mandate a change in the manufacturing technique to accommodate for the growing demand.