What is Lean Manufacuring?
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 manufacturing is a generic process management philosophy developed mostly by Toyota.
Lean manufacturing is a variation on the theme of efficiency based on optimizing flow; it is an instance of the recurring theme toward increasing efficiency, decreasing waste, and using empirical methods to decide what matters, rather than uncritically accepting pre-existing ideas.
For many, Lean is the set of "tools" that assist in the identification and steady elimination of waste. As waste is eliminated quality improves while manufacturing production time and cost are reduced. Examples of such "tools" are Value Stream Mapping, Five S (work place cleanliness), Kanban, (pull systems), and poka-yoke (error-proofing). The Value Stream Mapping tool has the greatest potential for applications in office areas for document flows and in IT application development. While in production areas Value Stream Mapping is used for inventory flows along with Five S, Kanban and poka-yoke.
5S is the name of a workplace organization methodology that uses a list of five Japanese words which, transliterated and translated into English, start with the letter S. This list is a mnemonic for a methodology that is often incorrectly characterized as "standardized cleanup", however it is much more than cleanup. 5S is a philosophy and a way of organizing and managing the workspace and work flow with the intent to improve efficiency by eliminating waste, improving flow and reducing process unevenness.
Kanban is a signaling system to trigger action. As its name suggests, kanban historically uses cards to signal the need for an item. However, other devices such as plastic markers (kanban squares) or balls (often golf balls) or an empty part-transport trolley or floor location can also be used to trigger the movement, production, or supply of a unit in a factory. kanban is a means through which JIT is achieved. It was out of a need to maintain the level of improvements that the kanban system was devised by Toyota. Kanban became an effective tool to support the running of the production system as a whole. In addition, it proved to be an excellent way for promoting improvements because reducing the number of kanban in circulation highlighted problem areas.
Poka-yoke is used by Toyota as a method for error proofing a production set of processes or inventory flows.
Toyota uses Value Stream Mapping primarily to study in-process inventory the flow of automotive parts through the various manufacturing processes in its factories. All automotive parts become more and more valuable as labor is expended on the parts going through the processes. The parts in this case, in-process inventory, just sitting around waiting between processes represents a loss in investment and warrants a Lean team study. The object is to identify all delays and to eliminate them if possible thus shorting the flow time and reducing inventory costs.
The Value Stream Mapping technique is used in office areas to analyze the flow of documents and or materials currently required to bring a product or service to a consumer.
Implementation of Value Stream Mapping
1. Identify the target product, product family, or service that is in need of reform.
2. Draw a current state value stream map, which shows the current steps, delays, and information flows required to deliver the target product or service. This may be a production flow (raw materials to consumer) or a design flow (concept to launch). There are 'standard' symbols for representing supply chain entities. This is time dependent mapping showing the time for all processes and losses due to delays.
3. Assess the current state value stream map in terms of creating flow by eliminating waste.
4. Draw a future state value stream map.
5. Implement the future map.
Where is it used?
Value stream mapping is commonly used in Lean environments to identify opportunities for improvement in lead time. Although value stream mapping is often associated with manufacturing, it is also used in logistics, supply chain, service related industries, healthcare, software development, product development and other functions.
Examples of how Lean is applied?
On the TV show "Extreme Makeover: Home Edition," the team constructs a house in only seven days, as opposed to the nine to 12 months it typically takes to build a new home. How does the team do it? By focusing on all time-wasters and eliminating them. The team doesn't cut corners — the family still gets a roof. But the "Makeover" crew finds a way to work on specific zones of the house while at the same time others are installing the plumbing.
That TV show is a perfect illustration of the opportunities in streamlining a set of processes. For almost any set of process, the actual labor accounts for less than 5 percent of the total time the processes take to complete a function. So in a nine-month permitting process, there may be about two weeks of actual hard labor. A hiring process may involve three days of work stretched out over three to four months. Where does all that time go? Batching, bottlenecks, backlog, checking, re-checking and CYA. A Lean approach works to eradicate the lost time by eliminating these barriers. When the system runs faster, we can get more done with the same resources.
An industry example of a continuous use of Lean
Lean has been used for years by the Boeing Company in its final assembly line to obtain efficiency in production of aircraft using Operation Sequence Charts. Each station in the assembly line has its own OSC which lists each operator by skill and the flow of his work assignment. The flow documents each process and when it is performed by the operator such that he is not working in the same zone as another operator. The OSC is design for a specific production rate and must be rebalanced if the product rate increases shortening the time allowed for the work station.
How Value Stream Mapping is done
The standard form suggests that the value-adding steps be drawn across the center of the map (a long paper) and the non-value-adding steps be represented in vertical lines at right angles to the value stream. Thus the activities become easily separated into the value stream which is the focus of one type of attention and the 'waste' steps another type. This is called the value stream the set of processes and the non-value streams the operations (usually waiting periods). The thinking here is that the non-value-adding steps are often preparatory or tidying up to the value-adding step and are closely associated with the person or machine/workstation that executes that value-adding step. Therefore each vertical line is the 'story' of a person or workstation whilst the horizontal line represents the 'story' of the product being created.
Hand drawn Value Stream Mapping versus using tools
The goal is to create a map, with minimum delay, while observing the target process in situation. Thus, value stream maps are usually drawn by hand in pencil to keep the mapping process simple and allow for simple correction. However, software tools are emerging as an alternative. A variety are available either as stand alone products or stencils/add-ons to products such as Microsoft Visio, allCLEAR and iGrafx FlowCharter.
Lawrence Rosier’s Comments on Getting the Most Out of Lean
I support the use of the lean method in every company and in government. Having said that, there are some issues I have identified, especially with the Lean reformers not going far enough.
In the state of Iowa the Lean hot teams reduced turnaround time for air-quality permits from 62 days to six days, and for wastewater discharge permits from 28 months to four-and-a-half months. This is great news for customers and for the state bureaucracy. Bureaucracies seek out anything that makes them look good to the public because it increases the possibility that their budgets will be increased.
Now let’s take a close look at how this was done. The question is? Were state employees just sitting around waiting for something to fall into their In-Baskets and the lean team organized them to jump in and get the job done. Could the new Lean document processing method be an antidote to the old In-Basket bureaucratic management method where “if your In-Basket is empty you don’t have anything to do” So employees let their In-Baskets build up a good sized backlog. After all it doesn’t cost the state anything only the customer has to wait months.
Clearly something is amiss because if the employees doing the processing of these documents could increase the turn around time by as much indicated in Iowa then there may be too many employees or there is an in balance in staffing. The staffing level could be set for processing the largest volume of documents rather than the average number of documents. I suspect the bureaucracy doesn’t even have clue as to what the staffing level should be. The Lean team ended their study by reducing document turnaround times. But this where the Lean team needs to continue their study to determine not only the best processes but also how to balance the staffing base to achieve the savings not only in the reduction of process time but also in reduced employee labor.
The determination of the proper staffing can be easily done because the Lean team knows the time to do the processes and it now must determine the number of times that the process is done over the budgeted time. If the work load proves to vary significantly such as seasonally the Lean team must find the best way to balance this work load. The best way to do this is to find other functions to work on in the off times. Then group these functions into sets of similar processes matched to the skills of employees and use work planning on a daily or weekly basis to balance the work load.