Lean is a philosophy of manufacturing that emphasizes the minimization of the amount of all resources (including time) used in operations of the company. Operations processes are considered to be Lean when they are very efficient and have few wasted resources. The elimination of WASTE is actually the defining principle of Lean. By eliminating waste of all sorts in the system, the lean approach lowers labour, materials, and energy costs of production. Lean also emphasizes building exactly the products customers want, exactly when they need them. When lean capabilities are introduced in a firm, it can produce smaller quantities, and it can change outputs more quickly in response to changes in customer demand. The primary objectives of Lean systems are to:
1. Produce only the products that customers want.
2. Produce products only as quickly as customers want them.
3. Produce products with perfect quality.
4. Produce in the minimum possible lead-times.
5. Produce products with features that customers want, and no others.
6. Produce with no waste of labour, materials or equipment.
7. Produce with methods that reinforce the occupational development of works. Eliminate Waste
Waste is anything that does not add value from the customer point of view. Storage, inspection, delay, waiting in queues, and defective products do not add value and are 100% waste. Seven Wastes: Overproduction, Queues, Transportation, Inventory, Motion, Over-processing and Defective products. Other resources such as energy, water, and air are often wasted. Efficient, sustainable production minimizes inputs, reduces waste. Traditional “housekeeping” has been expanded to the 7 Ss. Sort – when in doubt, throw it out. Simplify– methods analysis tools. Shine/sweep – clean daily. Standardize – remove variations from processes. Sustain – review work and recognize progress. Safety – build in good practices. Support/maintenance – reduce variability and unplanned downtime.
There are four building blocks that contribute to the building of a lean system. When these elements are focused in the areas of cost, quality and delivery, this forms the basis for a lean production system. They are:
1. Product design
2. Process design
3. Personnel/organizational elements
4. Manufacturing planning and control
Product design : Each process is crucial and contributes to an effective lean system. Product design consists of standard parts (workers have fewer parts to deal with), modular design (an extension of standard parts, they are separate parts clustered together and treated as one unit), highly capable production systems with quality built in ( JIT requires highly capable production systems), and concurrent engineering (keeping engineering practices shouldn’t change to avoid disruptions).The fact that customers have unique needs makes it necessary for the producer in the manufacturing sector or the service sector to create products and services that contributes uniquely to the final customer’s requirements. All design activities have performance objectives that are important to all designs. These objectives are: A design should be of high quality; it should be produced quickly, on a dependent basis, flexibility and at a low cost.
The three broad design categories, 1) the feasibility of the design, 2) the acceptability of the design, and 3) the vulnerability of each design option. Concurrent engineering-describes the process of collective product design by all affected functions in the organisation. Quality function deployment – is a planning tool used to fulfil customer expectations through a disciplined approach to product design engineering and production. Process Design: consists of small lot sizes (optimal one unit), setup time reductions, and manufacturing cells (specialized and efficient production centres, quality improvement, production flexibility, a balanced system (distributing workload evenly among the workstations), little inventory storage, and fail safe methods (incorporate ways to reduce or eliminate the potential for errors during the process). Lean systems have an extremely effective production method. Schedules must be communicated inside and outside the organization and Better scheduling improves performance and also Increases flexibility.
Personnel/organizational: elements includes workers as assets ( A JIT philosophy), Cross-trained workers (perform several parts of the process and operate several machines), cost accounting, and leadership/project management( a two-way communication process between managers and workers). Manufacturing planning and control: The last building block is manufacturing planning and control. It includes level loading,(achieving stable, level daily mix schedules) pull systems (work moves on in response to demand from the next stage in the process), visual systems (A kanban card used as authorization to move or work on parts), limited work-in-process, close vendor relationships, reduced transaction processing(logistical, balancing, quality, or change transactions), preventive maintenance and housekeeping(keeping the workplace clean and free of unneeded material. Improve employee communication. Identifying problems and driving out waste reduces costs and variability and improves throughput. Lean systems require managers to reduce variability caused by both internal and external factors. By pulling material in small lots, inventory cushions are removed; exposing problems and emphasizing continual improvement.
Lean operations began as lean manufacturing which was developed by the automobile manufacturer, Toyota. Toyota was sensitive to waste and inefficiency issues. The goal was to eliminate all waste from the process. Waste was identified by them as anything that interfered with the process or simply did not add value. Companies began adopting the lean approach and to do so realized that they had to do major changes in their organization and with their culture in the organization. Lean methods have demand-based operations, flexible operations with rapid changeover capability, effective worker behaviors, and continuous improvement efforts.
JIT system stands for a Just-In-Time system. It represents the philosophy that includes every aspect of the process from the design to after the sale. JIT is a highly coordinated processing system in which goods move through the system, and services are performed just as they are needed. First, management should decide if JIT is a compatible method for the company. JIT is best used with companies that have repetitive operations and a stable demand. The first step is planning the conversion to JIT. Managers need to be involved in the process and understand the commitment needed. The next step is to begin working only with suppliers who support the JIT system.
The biggest obstacles faced are management, worker or supplier disapproval, and also changing the culture of the company. Inventory is at the minimum level necessary to keep operations running. JIT Inventory Tactics: Use a pull system to move inventory; Reduce lot sizes; Develop just-in-time delivery systems with suppliers; Deliver directly to point of use; Perform to schedule; Reduce setup time; Use group technology. Different from JIT in that it is externally focused on the customer: Starts with understanding what the customer wants: Optimize the entire process from the customer’s perspective. The main benefits of lean operations systems are:
1. Reduced cost through reduced inventory levels
2. Higher quality
3. Reduced lead time
4. Increased productivity
5. Reduced amounts of waste
Inventories should never be used as the solution to fix machine malfunctions. One method that JIT systems uses to minimize inventory is to have suppliers deliver goods directly to the production floor. Overall, carrying low inventories offers many benefits such as less carrying cost, less space needed, and less rework to complete in case of a product recall. Lean systems can also be referred to as “just-in-time” (JIT) systems. The object of a lean system is to create a system that is demand driven, and provides supply based on demand at any given point. Lean systems tend to concentrate on waste reduction and have continuous improvement.