A systematic approach to identifying and eliminating waste through continuous improvement by flowing the product at the demand of the customer”.
Lean Manufacturing is a systematic approach for achieving the shortest possible cycle time by eliminating the process waste through continuous improvement. Thus making the operation very efficient and only consisting of value adding steps from start to finish. In simple words lean is manufacturing without waste.
Below are the few steps which are required to implement lean manufacturing
• Identifying the fact that there are wastes to be removed.
• Analysing the wastes and finding the root causes for these wastes.
• Finding the solution for these root causes.
• Application of these solutions and achieving the objective.
HISTORY OF LEAN MANUFACTURING:
Henry Ford was the first person to truly integrate an entire production process. In 1913, he integrated consistently interchangeable parts with standard work and moving conveyance to create what he called flow production.
Ford lined up fabrication steps in process order wherever possible. This was a revolutionary break from shop practices of the American system, that usually consisted of general-purpose machines grouped by process. Ford’s problem is that he could not provide the variety needed.
As Kiichiro Toyoda, Taiichi Ohno, and others at Toyota looked at this situation in the 1930s, and more intensely just after World War II, it occurred to them that a series of simple innovations might make it more possible to provide both continuity in process flow and a wide variety in product offerings. They therefore revisited Ford’s original thinking, and invented the Toyota Production System.
This system in essence shifted the focus of the manufacturing engineer from individual machines and their utilization, to the flow of the product through the total process. Toyota concluded that by right-sizing machines for the actual volume needed, introducing self-monitoring machines to ensure quality, lining the machines up in process sequence, pioneering quick setups so each machine could make small volumes of many part numbers, and having each process step notify the previous step of its current needs for materials, it would be possible to obtain low cost, high variety, high quality, and very rapid throughput times to respond to changing customer desires. Also, information management could be made much simpler and more accurate.
The though process of lean is described in 1990 in the book “The Machine That Changed the World,” by James P. Womack and Daniel T. Jones. In a later book, “Lean Thinking,” in 1996, Womack and Jones stressed five principles in lean:
· Specify the value required by the customer.
· Identify the Value Stream for each product.
· Make the product flow continuously through the remaining value-added steps.
· Introduce a ‘pull system’ where possible
· Manage towards perfection, so that the number of steps and the amount of time and information needed to serve the customer is continually reduced.
The term "lean" is used because Japanese business methods used less human effort, capital investment, floor space, materials, and time in all aspects of operations. The resulting competition among U.S. and Japanese automakers over the last 25 years has lead to the adoption of these principles within all U.S. manufacturing businesses.
THE BASIC LEAN MANUFACTURING PRINCIPLES:
The five-step thought process for guiding the implementation of lean techniques is easy to remember, but not always easy to achieve:
Specify value from the standpoint of the end customer by product family.
2. Value stream mapping
Identify all the steps in the value stream for each product family, eliminating whenever possible those steps that do not create value.
Make the value-creating steps occur in tight sequence so the product will flow smoothly toward the customer.
As flow is introduced, let customers pull value from the next upstream activity.
As value is specified, value streams are identified, wasted steps are removed, and flow and pull are introduced, begin the process again and continue it until a state of perfection is reached in which perfect value is created with no waste.
THE TRADITIONAL PRODUCTION VS LEAN MANUFACTURING.
In traditional manufacturing, costing is a vital process for charting production expenses; costing is the act of assigning costs to particular production activities and steps. The goal is to assign costs to the parts of production that actually produce related value, known as the matching principle. In this situation, costs are typically categorized by department or stage, with one cost being assigned for all resources, all labor and so forth.
In lean manufacturing, the traditional methods of costing create problems. Lean manufacturing tends to use techniques like work cells in order to easily adapt to new product needs and rapidly shifting production amounts. With a variety of different work cells, each often requiring its own types of labor, resources and machines, broad costing procedures do not work as well to represent production expenses. Accountants need to find more accurate ways of representing costs.
THE LEAN PRODUCTION GOALS:
The principal goal of lean manufacturing is to create a continuous flow of Product from raw material to finished goods and on to the customer – no stoppages, no delays, no Interruptions because of inventory scrap or yield issues, downtime or the other problems that occur in a typical manufacturing operation.
"maximizing value (give the customer what they exactly need)”
“Minimizing waste (eliminate anything not needed for delivering value)”
LEAN MANUFACTURING TOOLS & TECHNIQUES:
Here are some of the most important tools of lean, ones that a typical lean practitioner must be proficient it and capable of applying:
· Value Stream Mapping
· Takt Time
· Leveling (Heijunka)
· Pull Systems
· Setup Reduction
· Pokayoke (Mistake Proofing)
· Seven QC Tools
Value Stream Mapping
Value stream mapping is the identification of all the specific activities (material and information flow) as well as the resulting lead times occurring along the value stream for a particular product or product family, usually represented pictorially in a value stream map.
Takt time is the rate at which product must be turned out to satisfy market demand. It is determined by dividing the available production time by the rate of customer demand. It is a calculated number, not a reflection of your capability. It sets the pace of production to match the rate of customer
A measure of how frequently a process can produce all the items assigned to it. For example, if a machine is able to change over and produce the required quantity of all the high-running part types dedicated to it within three days, then the production batch size for each individual part type is about three days worth of parts. Thus this machine is making every part every three days.
Leveling is the sequencing of orders in a repetitive pattern, and the smoothing of day-to-day variations in total orders to correspond to longer-term demand.
A pull system is a system of production and delivery instructions in which nothing is produced by the upstream supplier until the downstream customer signals a need. Pull can operate with single units or small batches. It enables production without preset schedules.
checklists, worksheets, diagrams, area maps, etc., and may pertain to equipment use, operations,processes, metrics, storage, safety, quality, movement in an area, or general use of the environment.
Setup Reduction (Single Minute Exchange of Dies or SMED)
SMED is a series of operator techniques pioneered by Shigeo Shingo that result in change overs of production machinery in less than ten minutes. The long-term objective is always zero setup, in which changeovers are instantaneous and do not interfere in any way with one-piece flow.
Poka-yoke (Mistake Proofing)
Japanese term used by Shigeo Shingo to mean "innocent mistake-proofing," it is an improvement technology that uses a device or procedure to prevent defects or equipment malfunction during order-taking or manufacture. Mistake proofing devices are important to the production line in several ways:
(1) enforce correct operations by eliminating choices that lead to incorrect actions,
(2) signal or stop a process if an error is made or a defect created
(3) prevent machine and product damage.
Five S (5S) an improvement process, originally summarized by five Japanese words beginning with S, to create a workplace that will meet the criteria of visual control and lean production. Seiri (sort) means to separate needed tools, parts, and instructions from the unneeded and to remove the latter. Seiton (set in order) means to neatly arrange and identify parts and tools for ease of use.
Seiso (shine) means to clean and inspect. Seiketsu (standardize) means to require as the norm that everyone sort, set in order, and shine at frequent (daily) intervals to keep the workplace in perfect condition, and also to make use of visual control systems. Shitsuke (sustain) means to maintain the five S gains by training and encouraging workers to form the habit of always following the first four Ss.
SEVEN QC TOOLS:
Check sheet or tally sheet
Cause and effect diagram
Process flow chart
JIT (JUST IN TIME):
Just in time (JIT) is a production strategy that strives to improve a business return on investment by reducing in-process inventory and associated carrying costs. To meet JIT objectives, the process relies on signals or Kanban between different points in the process, which tell production when to make the next part. Kanban are usually 'tickets' but can be simple visual signals, such as the presence or absence of a part on a shelf. Implemented correctly, JIT focuses on continuous improvement and can improve a manufacturing organization's return on investment, quality, and efficiency. To achieve continuous improvement key areas of focus could be flow, employee involvement and quality.
Kanban is one of most popular tools in lean manufacturing. This is a simple concept, but very effective. Kanban mainly focus on the reduction of overproduction. There are mainly two types of kanbans. They are
BENEFITS OF LEAN MANUFACTURING
The implementation of lean manufacturing through trying to make value flow at the pull of the customer (Just In Time) prevents and eliminates waste in your processes. Waste being categorized as part of the seven wastes: Transport, Inventory, Motion, Waiting, Over-processing, Overproduction, and Defects.
Many studies have shown that we only add value for around 5% of the time within our operations, the remaining 95% is waste! Imagine if you could remove that 95% wasted time and effort; what would it do for your operations?
Typically Lean will improve
Quality performance, fewer defects and rework (in house and at customer).
Fewer Machine and Process Breakdowns.
Lower levels of Inventory.
Greater levels of Stock Turnover.
Less Space Required.
Higher efficiencies, more output per man hour.
Improved delivery performance.
Greater Customer Satisfaction.
Improved employee morale and involvement.
Improved Supplier Relations.
Are these not good enough reasons to implement Lean?