Lean Manufacturing
Lean manufacturing is a systematic approach to identifying and eliminating wastes through continuous improvement by conveying the product at the pull of the customer in pursuit of production.
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.
- Analyzing 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:
Lean vs Traditional Manufacturing Process:
For years manufacturers have created products in anticipation of having a market for them. Operations have traditionally been driven by sales forecasts and firms tended to stockpile inventories in case they were needed. A key difference in Lean Manufacturing is that it is based on the concept that production can and should be driven by real customer demand.A lean organization can make twice as much product with twice the quality and half the time and space, at half the cost, with a fraction of the normal work-in-process inventory. Lean management is about operating the most efficient and effective organization possible, with least cost and zero waste
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)
- Pursuing perfection
- Reduce Time
- Reduce Total Costs
Cost Reduction by Elimination of Waste
It requires constant effort at cost reduction to maintain continuous profits in manufacturing. The prime way to reduce costs is to produce only those products determined by sales in a timely fashion, to restrain excessive manufacturing and to eliminate all waste in manufacturing methods. There are various ways to analyze and implement cost reduction, from the start of designing all the way through to manufacturing and sales. One of the goals of Lean Manufacturing is to locate waste pragmatically in each process and then eliminate it. It is possible to uncover a very large amount of waste by observing employees, equipment, materials and organization in the actual production line from the perspectives of the process itself and the actual work involved. Some types of waste are obvious, but others are hidden. Waste never improves value; it only increases cost. The thorough elimination of waste leads to greater employee self-respect and to major cost reductions by preventing unneeded losses.
Creating Conditions to Guarantee Product Quality
To produce a high-quality product is the first commandment of any manufacturing company. The high quality of any product, in which many component and parts do not fail and are trouble free, must be built into it at every process. Lean Manufacturing has developed various ways to support the commitment to “build the quality into the process.” This principle gives each operator the responsibility to check quality thoroughly at every stage of work within the process, and brings product inspection directly into the process so that good products flow to the following process and defects are extracted at that point. Each operator must be aware that “the following process is a customer” and must never send a defective product to downstream processes. If equipment is defective or operates abnormally, either the machine itself or some system must be able to detect the problem and stop operation. Foolproof devices are often used as simple means for this purpose. This also makes it easier to maintain quality. Lean Manufacturing has taken many measures and expended much effort to see that, if a defect in quality should occur, we can uncover the true cause and apply countermeasures to prevent its recurrence.
Creating a Work Site with Operators in Mind
If labor is expended on a product but does not contribute any additional value to it, that labor is of no value. On the other hand, if the labor expended on a product enhances the product’s value, then that labor is of great value because it is effective. This type of effective labor use translates into showing respect for human dignity, the dignity of the employee. In the Lean Manufacturing measures have been taken so that the labor or every employee will
enhance the value of our products. One of these measures is Standardized Work. This is a way to perform the most effective sequential production without waste by rationally concentrating the work around the Operators’ movement. Some companies use a system that stresses the performance of equipment and machines. In this case, the equipment is considered to be of prime importance and the employee mere expansion of the machine. Mutual support is indispensable if each employee, who plays the leading role for his particular task, is to perform the work and improve the efficiency of the whole production process. In Lean Manufacturing the implementation of mutual support between the preceding and succeeding processes has affected highly efficient work. If the Operator discovers some problem in the work for which he is responsible, he or she is permitted to stop the line depending on the gravity of the problem. This is only possible against
a backdrop of respect for the judgment and intelligence of the employees. A work site, where every employee can fully display his own ability, can be created with a system in which the work accomplishments of each individual are a matter of public knowledge, and anyone can propose kaizen for work problems.
Awareness of Waste
Cost Reduction versus Cost Plus
Lean Manufacturing improves productivity through the principle of Cost Reduction.
With the principle of cost reduction, the sales price of a product is determined by actual market
conditions. A profit cannot be secured, thus, without first reducing cost regardless of increases
or decreases in the production quantity. This type of cost philosophy requires an overall
company effort. Cost reduction is:
Profit = Sales price – Cost
In contrast to cost reduction, there is the cost-plus principle, in which product price is
determined by combining all the costs -- such as those of raw materials, labor and other
expenses needed for production -- with whatever company policy decides is needed as profit.
Cost policy:
Sales price = Cost + Profit
The two formulas above are the same mathematically, but there is a great difference in the
emphasis each one places on the variables. In other words, cost-plus considers that the cost is
fixed. While cost reduction considers, that the cost can be effectively changed by
manufacturing methods.
Main Kinds of Wastes
Seven main types of wastes were identified as a part of the Toyota Production System. However, this list has been modified and expanded by various practitioners of lean manufacturing and generally includes the following:
Overproduction
It is unnecessary to produce more than the customer demands, or producing it too early before it is needed. This increases the risk of obsolescence and the risk of producing the wrong thing. It tends to lead to excessive lead and storage times. In addition, it leads to excessive work-in-process stocks which result in the physical dislocation of operations with consequent poorer communication
Defects
In addition to physical defects which directly add to the costs of goods sold, this may include errors in paperwork, late delivery, production according to incorrect specifications, use of too much raw materials or generation of unnecessary scrap. When defect occurs, rework may be required; otherwise the product will be scrapped. Generation of defects will not only waste material and labor resources, but it will also create material shortages, hinder meeting schedules, create idle time at subsequent workstations and extend the manufacturing lead time.
Inventory
It means having unnecessarily high levels of raw materials, works-in-process and finished products. Extra inventory leads to higher inventory financing costs, higher storage costs and higher defect rates. It tends to increase lead time, prevents rapid identification of problems and increase space requirements. In order to conduct effective purchasing, it is especially necessary to eliminate inventory due to incorrect lead times.
Transportation
It includes any movement of materials that does not add any value to the product, such as moving materials between workstations. Transportation between processing stages results in prolonging production cycle times, the inefficient use of labor and space. Any movement in the
firms could be viewed as waste. Double handling and excessive movements are likely to cause damage and deterioration with the distance of communication between
processes.
Waiting
It is idle time for workers or machines due to bottlenecks or inefficient production flow on the factory floor. It includes small delays between processing of units.When time is being used ineffectively, then the waste of waiting occurs. This waste occurs whenever goods are not moving or being worked on. This waste affects both goods and workers, each spending time waiting. Waiting time for workers may be used for training or maintenance activities and should not result in overproduction
Motion
It includes any unnecessary physical motions or walking by workers which divert them from actual processing work. This might include walking around the factory floor to look for a tool, or even unnecessary or difficult physical movements, due to poorly designed ergonomics, which slow down the workers. It involves poor ergonomics of production, where operators have to stretch, bend and pick up when such actions could be avoided.
Over-processing
It is unintentionally doing more processing work than the customer requires in terms of product quality or features such as polishing or applying finishing in some areas of product that will not be seen by the customer . Over-processing occurs in situations where overly complex
solutions are found to simple procedures. The over-complexity discourages ownership and encourages employees to overproduce to recover the large investment in the complex machines.
The Eighth Waste – Skills
Sometimes in focusing on the elimination of the seven wastes, companies forget about the aspect of Lean that is inherent in the philosophy as it was originally developed in Japan – respect for people. In other words, the recognition that a company’s most important assets are its employees. To that end, Lean practitioners sometimes add an eighth waste to the list – skills. This waste occurs when company does not fully leverage the gifts and talents of its associates. In fact, employees may even decide to leave a company for the simple reason that they do not feel as though they are being listened to or valued, and, as such, they feel like a number in a sea of numbers.
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:
1. Value
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.
3. Flow
Make the value-creating steps occur in tight sequence so the product will flow smoothly toward the customer.
4. Pull
As flow is introduced, let customers pull value from the next upstream activity.
5. Perfection
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.
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
• EPEI
• Leveling (Heijunka)
• Pull Systems
• Setup Reduction
• Pokayoke (Mistake Proofing)
• 5S
• Seven QC Tools
• JIT
• Kanban
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
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
demand.
EPEI
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 (Heijunka)
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.
Pull Systems
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 changeovers 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.
5S
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
- Histogram
- Pareto chart
- Cause and effect diagram
- Process flow chart
- Control chart
- Scatter diagram
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 TOOLING:
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
- Withdrawal kanban
- Production kanban
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.
- Faster Development.
- Greater Customer Satisfaction.
- Improved employee morale and involvement.
- Improved Supplier Relations.
- HIGHER PROFITS!
- INCREASED BUSINESS
