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Lean Thinking Part II: The Fundamental Blocks of Lean
Part II in a series on lean manufacturing strategies with a focus on the forest products industry, covers the fundamental building block of lean manufacturing.
By Dr. Henry Quesada, Dr. Urs Buehlmann
Date Posted: 10/1/2010
This is part II of a series of articles on lean manufacturing strategies with a focus on the forest products industry.
Lean thinking is more than just a buzzword. It is a real-world business philosophy that can help prepare your company for the future. The first article in this series covered the basics of lean manufacturing. This article describes the fundamental blocks that support lean thinking.
We will start with the basic blocks or lower levels (5s system, visual controls, plant layout, standardized work, quality at the source, and quick changeover) and then follow up with the ones that require more technical expertise.
The purpose of a 5S program or event is to keep a clean and safe workplace environment where workers will have greater motivation to do their work while eliminate waste in all forms. 5S stands for five Japanese words: Seiri (sort, e.g., Classification), Seiton (set in order, e.g., Organization), Seiso (shine, e.g., Clean; Shine), Seiketsu (standardize; e.g., Standardization), and Shitsuke (sustain, e.g., Discipline). A more detailed description of these five activities follows:
• Classify: Serves as the basis for further action. Classification provides a basic framework to structure items. For example, objects can be classified as necessary and unnecessary. Or items can be classified according to their frequency of use and physical size. Once items and objects have been classified, all unnecessary items must be disposed of accordingly and the remaining items be positioned according to their frequency of use and physical size.
• Organize: This process guides workers to organize all items and objects that are necessary to do the work. Tools and items not sorted out are properly identified and stored so that they can be easily accessed when needed.
• Clean: Employees are asked to thoroughly clean their workplace. Once an area is clean, employees are encouraged to keep it that way. This requires cleaning to be integrated into the daily work schedules.
• Standardization: Once employees create a clean, organized, and well-maintained workplace, standardization is used to make sure that the workplace remains in this condition. Audits, evaluations, and training activities are important to embed standardized ways of doing things into the employees’ normal work routine.
• Discipline: The most challenging category of the 5S system is discipline. This requires all company associates to follow, understand, and practice the rules to sustain the 5S system. A system rewarding good performance in sustaining 5S has to be created to embed 5S behavior into the employees’ behavior, making it the company culture.
Five S events are considered the starting point when starting the lean manufacturing journey. However, to sustain and advance the never ending strife to eliminate waste and focus on value-added activities, other important tools are available to the lean practitioner. Some of these are discussed below:
Visual control is a communication management system that can be used in all parts of an organization. Based on the principle that a picture says more than a thousand words, the system stipulates that the visual be in the right place at the right time. Given the right visual at the right place and time assures good communication with team members.
A visual language needs to be developed and become the standard throughout an organization so it can be used and understood by everyone.
Standardized work eliminates or decreases variability when different people perform the same or similar operations or when the same or similar operations are performed at different locations. For instance, if two workers in a pallet business are assembling the same custom sized pallet, they may have different cycle times (e.g. the time from starting a task for one unit to the moment when the next unit is started) to get one pallet assembled. If worker one finishes the operation in 65 seconds and worker two only needs 50 seconds, the operation becomes unbalanced. Also, the slower worker likely can benefit from the experience of the faster worker. Having two cells doing the same thing but having different cycle times (65 vs. 50 seconds) creates an unbalance for the following operations.
The two operators work out a pallet assembly standard, which they are both trained on and follow closely after training, resulting in an even, balanced output of assembled pallets. At the same time, standards also help guarantee quality and safety standards. Thus, standardized work provides the basis for high level productivity, quality, and safety.
Standard work also leads to the collection of best work methods and procedures and documents them for further improvement in the future. One of the core tools for standardized work is the standards work sheet, which lists the sequence of tasks, individual task performance descriptions, time needed for each task and total cycle time for the entire process. Additional information regarding quality metrics and safety guidelines can be added to the standard work sheet.
The organization of equipment, workstations, people, and space is critically important for reducing waste, creating flow, assuring quality, and safety. A growing company needs to become more efficient using the same space making its products to avoid the substantial costs of adding space. An efficient plant layout helps minimize products’ traveled distance, increases parts flow, and decreases cycle time. There are four types of plant layouts: product, process, hybrid, and cellular.
A product layout arranges machines and workstations according to the sequence of operations required to produce a good. This type of layout is considered rigid with little space for product flexibility but efficient for manufacturing the products it was intended for. For instance, an I-joist manufacturing operation is considered a process layout where I-joists flow from one process step to the next in adjacent cells. Conversely, in a process layout machines and workstations are arranged by processes. As an example, a pallet manufacturing plant can have specific departments for specific processes, such as cross cutting, ripping, machining, assembly, finishing, and packaging processes and all products will be moved through those departments.
The products are routed through these processes based on the process requirements listed on each product’s route-sheet. In reality, a large number of layouts are hybrid (a mix between process and product layouts) which in some instances increase flexibility, support larger production volumes, increase machine utilization, and increase parts flow.
A cellular manufacturing layout reassembles a product layout configuration, but on a smaller scale. Machinery and processes are set-up in a small space so traveling distances and unnecessary movements are minimized or eliminated. At the same time, a cellular layout increases parts flow, minimizes waiting times, decreases work in process inventory (WIP), and reduces costs. However, it may require duplication of some machines or processes.
Quality at the Source
Quality control has become an indispensable manufacturing support process to assure defect-free products. Unfortunately, more often than not quality control has been institutionalized and relies on after-the-fact inspections. Such inspections are non-value adding, as the part is either within specifications (i.e., an inspection is unnecessary) or the part is outside specifications, thus all the resources spent on processing the part are wasted.
Quality must be built at the source (i.e. into the process where errors could occur) and inspected congruently with the process execution by the operator. One way of making sure quality is built at the source are failsafe devices. These devices or systems do eliminate the possibility of errors. Examples of mistake proof devices include go and no go gages, visual and audio alarms, limit switches, counters, and checklists.
The most widespread example of mistake proof thinking can be found on every computer – the video output plug will not fit into an audio plug and vice versa. Depending on the manufacturing process, one or a combination of these failsafe devices or systems may be used to prevent errors being made.
These fundamental or lower level blocks of lean thinking need to be mastered before the organization moves forward to the more advanced blocks. As it was mentioned in the first article of this series, team work is one of the glues that holds it all together. There is no recorded lean effort that has been successful based only on individual efforts. Although a process manager or general manager might try to become a hero, these individual heroic endeavors usually end up in sterile ground.
In our next article, we will go through the higher level blocks of lean thinking. If your organization wishes to start the lean journey, Virginia Tech offers in-house training and consulting in lean thinking practices. Getting an expert to help can make your entire process more effective. If you have questions or want to know more about our training programs, please contact us at email@example.com or visit www.woodinnovation.org.
Dr. Henry Quesada is an assistant professor at Virginia Tech specializing in the area of business management processes and modern manufacturing systems. He works primarily with the forest products industry. If you have any questions please feel free to contact Henry Quesada at firstname.lastname@example.org. Dr. Urs Buehlmann is an associate professor at Virginia Tech focusing on manufacturing systems, engineering, business competitiveness and globalization.