The Seven Wastes of Lean Manufacturing
Eliminating waste is a no-brainer, right? It’s hard to quarrel with the merits of eliminating waste. However, accomplishing it is another story. We’ve all had the experience of witnessing inadvertent waste in manufacturing. Sometimes it’s obvious, and sometimes it takes some detective work, but it’s always worth pursuing and eliminating in the interest of greater profitability and quality.
The principles of Lean Manufacturing include identifying and eliminating waste. Lean Manufacturing recognizes seven categories of waste: Transport, Inventory, Motion, Waiting, Overproduction, Over-Processing, and Defects. Let’s briefly discuss each, along with strategies to combat them in manufacturing.
The Waste of Transport
Transport describes movement of product in any context. It might be from the warehouse to the shop floor, or from the overseas supplier to the facility itself. Transporting the product is necessary, but it doesn’t transform the product or add value to it. It incurs costs for the equipment and staff to move it; safety measures and training; space for receiving it. It relates to other wastes: product delivered late can cause the waste of waiting, product delivered early demands storage (the waste of inventory). Damage can be associated with travel, whether small dings and dents, or entire containers lost to shipwreck, fire or flooding.
Reducing the Waste of Transport
Map product flows to determine which processes should be next to each other. Change layout to create value streams. Include all of the value adding processes in production lines or cells. Minimize space between operations.
The Waste of Inventory
Inventory waste refers to the waste caused by superfluous inventory. Resources wasted include storage space (along with utilities like lighting and heating), capital, containers, increased lead times and more. Damage and deterioration may take place. Excess inventory can conceal problems on the plant floor, which ought to be identified and resolved.
Reducing the Waste of Inventory
Adhere to Just in Time (JIT) production and stop overproducing beyond demand. Evaluate the factory and cell layout, and schedule your production processes to ensure that WIP (work in progress) does not accumulate between processes.
The Waste of Motion
Motion entails the movements of both humans and machines. In the case of humans, think ergonomics: minimizing the stress of lifting, bending, stretching, walking, and reaching. It also includes searching for tools and equipment, and walking to retrieve components or use machines. In the case of machines, it may describe excess motion and processing, which may cause unnecessary wear and tear on machines.
Reducing the Waste of Motion
For employees, this is a health and safety issue. Redesign flows for the physical ease of plant personnel. For machines, critically analyze processes and revamp to minimize unnecessary motion.
The Waste of Waiting
When goods are neither moving nor being processed, the waste of waiting takes place. Generally more than 99% of a product’s life in traditional manufacturing is spent waiting to be processed. A product may wait for the next operation because production runs are too long, material flow is poor, and distances between work centers are excessive. Associated environmental wastes include wasted labor and utilities for lighting, heating, or cooling during the waiting period.
Reducing the Waste of Waiting
Revise processes so that one feeds directly into the next. If one element of the production chain takes longer than others, it results in idle time for the next employee down the line. The time-consuming task must be made more efficient to eliminate this gap.
The Waste of Overproduction
Overproduction is simply the manufacture an item before it is actually required. This is in conflict with the principles of “Just in Time” (JIT), which dictates that every item is made just as it is needed. In contrast, overproduction can be described as “Just in Case.” It creates excessive lead times, which increases storage costs, ties up capital, and camouflages defects. Products may spoil or become obsolete, further increasing costs.
Reducing the Waste of Overproduction
The solution is scheduling and producing only what can be immediately used, sold or shipped. Improving machine changeover/set-up capability supports this process. Overproduction often hides problems which will be revealed during this process.
The Waste of Over-Processing
This often refers to using expensive, high-precision equipment when simpler tools would suffice. The expense of these machines encourages high asset utilization (meaning over-production to achieve minimal changeovers) in order to recover the initial investment. It also refers to including features that will not be used. Any time you add more value than the customer requires, you are over-processing.
Reducing the Waste of Over-Processing
Rely on smaller, more flexible machines whenever possible. Combine steps to reduce inappropriate processing. Revise processes with simplification and efficiency in mind.
The Waste of Defects
A defect refers to a product which does not meet the standards of its design or the customer’s expectations. They are very costly: they must be replaced; they require human labor and documentation to process; they may alienate customers; they waste raw materials; they require rescheduling and re-inspecting.
Reducing the Waste of Defects
The increased efficiencies dictated by addressing the other six wastes should result in a more efficient production system which both reduces defects and increases the resources needed to address them in the first place. Capitalize on employee feedback and increased manufacturing efficiencies to reduce defects.