Principles of lean thinking have been broadly accepted by many manufacturing operations and have been applied successfully across many. Different authors define it distinctively. Lean manufacturing is most frequently associated with the elimination of seven important wastes to ameliorate the effects of variability in supply, processing time or demand defined it as a philosophy of manufacturing that focuses on delivering the highest quality product on time and at the lowest cost. Worley (2004) defined it as the systematic removal of waste by all members of the organization from all areas of the value stream.
Briefly, it is called lean as it uses less, or the minimum of everything required to produce a product or perform a service. In a nutshell, lean manufacturing can be best defined as an approach to deliver the upmost value to the customer by eliminating waste through process and human design elements. Lean manufacturing has become an integrated system composed of highly inter-related elements and a wide variety of management practices, including Just-in-Time (JIT), quality systems,work teams, cellular manufacturing etc.The purpose of implementing it is to increase productivity, reduce lead time and cost, and improve. Lean manufacturing requires that not only should technical questions be fully understood, but existing relationships between manufacturing and the other areas of the firm should also be examined in depth, as should other factors external to the firm As an integrative concept, the adoption of lean manufacturing can be characterized by a collective set of key areas or factors.
These key areas encompass a broad array of practices which are believed to be critical for its implementation. They are, scheduling, inventory, material handling, equipment, work processes, quality, employees, layout, suppliers, customers, safety and ergonomics, product design, management and culture, and tools and techniques. These 14 areas are the subjects of investigation in this study and each of them will be reviewed and described now. Scheduling - Effective schedules improve the ability to eet customer orders, drive down inventories by allowing smaller lot sizes, and reduce work in processes.
Appropriate scheduling methods are able to optimize the use of resources. Pull methods such as Kanban, and lot size reduction are commonly used to reduce storage and inventories and to avoid overproduction. Pull means to do nothing until it is required by the downstream process. Minimizing lot sizes enables a smoother production flow and maximizes productivity by eliminating production line imbalances.Companies store inventories to enable continuous deliveries and overcome problems such as demand variabilities, unreliable deliveries from suppliers, and breakdowns in production processes.
However there is a need to maintain inventories at the minimum level because excess inventories would require more valuable spaces and result in higher carrying costs. Moreover, they accumulate the risk of “products becoming obsolete”. Excess inventories are seen as “evils” because they hide problems such as defects, production imbalances, late deliveries from suppliers, equipment downtime and long setup time.Material handling is also crucial in lean manufacturing because the cost attributed to material handling is estimated between 15% and 70% of the total manufacturing operation stated that transporting parts not only does not add value to a product, it increases manufacturing lead time.
Hence, it is a major waste that needs to be eliminated. A steady material flow which moves frequently in small batches will allow a faster replenishment of materials. This will then shorten lead time and increase productivity.The level of equipment support should be given attention in lean manufacturing because some manufacturing processes rely heavily on their equipment to produce products. Unexpected machine downtime would result in line stoppage and decrease productivity. Therefore, equipment is a vital area in which maintenance and reduction of setup time play an important role to avoid process disturbance.
Lean manufacturing requires machines which are reliable and efficient. Inventories can be reduced when machine downtime is minimized.Work processes across the value stream should also be emphasized in lean manufacturing. Processes should be performed with a minimum of non value added activities in order to reduce waiting time, queuing time, moving time, and other delays Besides this, standardization of work processes is needed to facilitate efficient, safe work methods and eliminate wastes, while maintaining quality.
Itensures a consistent performance and creates a foundation for continuous improvement.Nowadays, a product with high quality is a prerequisite for any manufacturer. Quality is a major focus in lean manufacturing because poor quality management would result in many wastes such as scraps and rejects. Appropriate quality management helps to control a manufacturing process, and this reduces “safety” buffers and exposes quality issues.
Reduction of “safety” buffers will eventually lead to reduction of inventories. Employees who are motivated and empowered are essential since people are the key element in lean manufacturing.Japanese regard people as assets because they are the ones who are going to solve problems and improve processes in production. Another key area of lean manufacturing is layout which determines the arrangement of facilities in a factory. A poor layout may have several deteriorating effects such as high material handling costs, excessive work-in-process inventories, and low or unbalanced equipment utilization. Suppliers have been reported as a critical factor for the success oflean manufacturing and they have been given much attention by various researchers.
Particularly, it is important to encourage suppliers to develop JIT production capabilities as well as JIT delivery in order to enhance long-term competitiveness. A mutual goal between manufacturers and suppliers to reduce waste and cut down cost is crucial to drive lean manufacturing to success. Relationship with customers is also crucial in lean. Customers decide what to buy, and when and how they are going to purchase a product. Since value is determined by the customers, it is essential to develop a good relationship with them.
Setting up good relationships with customers will enable an organization to understand and meet their needs and predict their demands accurately, as it is important to attain a perfect match between market demands and production flows. Safety and ergonomics are incorporated as an area in lean manufacturing. Safety should be emphasized since it is the foundation of all activities. Ergonomics is also important because it helps humans to improve productivity, reduce injuries and fatigues.
By using ergonomic features, unnecessary motions (one of the major wastes) are decreased.This helps to reduce mistakes caused by human errors, thus enhancing the quality of products. Product design is also important because the choices of product structures and materials would affect the production methods and costs. Essentially, management and culture are considered as a key area in this study.
It is critical for top management to understand and give ample support to sustain the lean concept. Communication between senior managers and employees is critical to ensure that the vision and mission of lean manufacturing is attainable.Evidence shows that management support plays a vital role in driving lean manufacturing implementation . Recognition and rewards from top management will serve as a booster for participation and continuous improvement.
In addition, culture is the main pillar when implementing lean manufacturing. Finally, tools and techniques are indispensable in implementing lean manufacturing.. Lean tools that are systematically applied or implemented can help to define, analyze and attack sources of waste in specific ways. There are many excellent tools that are useful in different circumstances.Using tools such as value stream mapping, jidoka, 5S, kanban etc, will assist organizations to go along with lean manufacturing transformation.
Lean tools are urged to be used in an integrated way rather than applying them in isolation. Why Lean Manufacturing? Companies embrace Lean Manufacturing for three fundamental reasons. First, the highly competitive, globalized market of the late 20th and early 21st century require that companies lower costs to increase margins and/or decrease prices through the elimination of all non-value added aspects of the enterprise.In other words, companies need to key in on Ford’s production efficiency ideals. Second, customer responsiveness is key.
This means embracing the notion of production efficiency developed by Ford, but also doing what Ford couldn’t: meet rapidly changing customer “just-in-time” demands through similarly rapid product mix changes and increases in manufacturing velocity. Finally, producing desired goods quickly won’t maintain a market share if the product isn’t of high and consistent quality. Thus, efficiency, responsiveness, and quality are three key goals of Lean Manufacturing.
