The search by manufacturers for solutions to the rigid rules mandated by their MRP systems has led many to the techniques of Lean manufacturing. Lean manufacturing methodologies are not new technologies for the millennium, but are, in fact, a compilation of many of the techniques manufacturers have used in the past and are familiar with. The difference is the consolidation of these techniques into one set of powerful methodologies and their application. Achieving Lean goals using one-piece Lean manufacturing methods is essentially a line-balancing methodology used in conjunction with a series of kanban material-handling techniques. Mathematical models are created and iterated until the optimum utilization of manufacturing resources is identified.
Specifically, the Lean manufacturing methodologies are a series of techniques that allow product to be produced one unit at a time, at a formulated rate, while eliminating nonvalue-adding wait time, queue time, or other delays. Product is pulled through the line, in response to actual demand as opposed to being pushed through by the launch of orders based on the output of a planning system. Thought of in terms of a pipeline, discrete product can be made to move through the manufacturing processes without stopping. If product can move without stopping, it can be thought of much like liquid through a pipeline. This metaphor of moving product through a pipe is the source for the term flow.
If only the actual touch work time required to produce a product through its various manufacturing processes were summed, that time is almost always shorter than the time required to route batches of products through a factory one department at a time . Typically, the sum of the times required to route product through manufacturing becomes the customer-quoted lead time. Often, this customer-quoted lead time becomes a self-fulfilling prophecy to the detriment of achieving customer satisfaction. The Lean manufacturing methodologies consider all the other times associated with moving "lot-sized" orders through manufacturing as "nonvalue-added" time. Lean seeks to eliminate this nonvalue-added time.
The goal of Lean manufacturing, then, is to establish and design a manufacturing line capable of producing multiple products, one at a time, using only the amount of time required to actually build the product. The techniques of Lean manufacturing seek to reduce the nonvalue-adding wait, scheduling, and queue times to zero. The resulting, often significant, reduction in manufacturing lead time is the basis for all the associated benefits of Lean manufacturing.
A Lean manufacturing line requires that a rate of flow through the pipeline be established. The rate at which work progresses through the factory is called a flow rate or Takt. The "flow" of a product is achieved by causing all of its work tasks to be grouped and balanced to a calculated formulated Takt time. Takt time establishes a relationship between volume and the time available to produce that volume.
Takt time, in most cases, is expressed in minutes or percentage of a minute.
Regardless of the total time necessary to produce a product, its total time is divided into elements of work equal to its Takt time. A single unit of work (a Takt time's worth) is performed by a person and/or a machine. The partially completed unit is then passed to the next resource down the line, where another "Takt" worth of work tasks is performed. The unit of work progresses sequentially through all the manufacturing processes until all of the required work has been completed
Lean manufacturers can choose to change the output of the line to closer match the mix and volume of customer requirements. With a line designed to produce products using a formulated Takt time, the Lean manufacturer has the ability to regulate the "rate" and, therefore, the output of the line. This rate must be determined every day based on that day's customer requirements.
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This ability to change output rate every day, driven by changes in customer order requirements, is a powerful tool for managing both work-in-process and finished goods inventories. With this capability, a manufacturer is no longer forced to commit its manufacturing resources to a schedule driven by a questionable forecast of future demand.
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excerpts from the book: LEAN Manufacturing Implementation: A Complete Execution Manual for Any Size Manufacturer
Author: Dennis P. Hobbs
Specifically, the Lean manufacturing methodologies are a series of techniques that allow product to be produced one unit at a time, at a formulated rate, while eliminating nonvalue-adding wait time, queue time, or other delays. Product is pulled through the line, in response to actual demand as opposed to being pushed through by the launch of orders based on the output of a planning system. Thought of in terms of a pipeline, discrete product can be made to move through the manufacturing processes without stopping. If product can move without stopping, it can be thought of much like liquid through a pipeline. This metaphor of moving product through a pipe is the source for the term flow.
If only the actual touch work time required to produce a product through its various manufacturing processes were summed, that time is almost always shorter than the time required to route batches of products through a factory one department at a time . Typically, the sum of the times required to route product through manufacturing becomes the customer-quoted lead time. Often, this customer-quoted lead time becomes a self-fulfilling prophecy to the detriment of achieving customer satisfaction. The Lean manufacturing methodologies consider all the other times associated with moving "lot-sized" orders through manufacturing as "nonvalue-added" time. Lean seeks to eliminate this nonvalue-added time.
The goal of Lean manufacturing, then, is to establish and design a manufacturing line capable of producing multiple products, one at a time, using only the amount of time required to actually build the product. The techniques of Lean manufacturing seek to reduce the nonvalue-adding wait, scheduling, and queue times to zero. The resulting, often significant, reduction in manufacturing lead time is the basis for all the associated benefits of Lean manufacturing.
A Lean manufacturing line requires that a rate of flow through the pipeline be established. The rate at which work progresses through the factory is called a flow rate or Takt. The "flow" of a product is achieved by causing all of its work tasks to be grouped and balanced to a calculated formulated Takt time. Takt time establishes a relationship between volume and the time available to produce that volume.
Takt time, in most cases, is expressed in minutes or percentage of a minute.
Regardless of the total time necessary to produce a product, its total time is divided into elements of work equal to its Takt time. A single unit of work (a Takt time's worth) is performed by a person and/or a machine. The partially completed unit is then passed to the next resource down the line, where another "Takt" worth of work tasks is performed. The unit of work progresses sequentially through all the manufacturing processes until all of the required work has been completed
Lean manufacturers can choose to change the output of the line to closer match the mix and volume of customer requirements. With a line designed to produce products using a formulated Takt time, the Lean manufacturer has the ability to regulate the "rate" and, therefore, the output of the line. This rate must be determined every day based on that day's customer requirements.
******************************
This ability to change output rate every day, driven by changes in customer order requirements, is a powerful tool for managing both work-in-process and finished goods inventories. With this capability, a manufacturer is no longer forced to commit its manufacturing resources to a schedule driven by a questionable forecast of future demand.
******************************
excerpts from the book: LEAN Manufacturing Implementation: A Complete Execution Manual for Any Size Manufacturer
Author: Dennis P. Hobbs
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