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Lean

Enable continuous flow


The key to optimizing material, people, and information is to strive for “one-piece,” or continuous flow from suppliers, through the work steps, to the customer. Many different Lean techniques are used to remove barriers to continuous flow, and there are many types of barriers! The goal is to design processes that produce stable and predictable output, and that are capable of producing to takt. Flow can only be achieved when each process can keep up with customer demand and the product is defect free.

Teams should immediately start to eliminate sources of waste and non-value added activities. Remember that the definition of value is from the perspective of the customer! Any activity that does not contribute directly to the value of end product – anything the customer would not pay for – is waste. Use detailed process maps to identify steps that do not add value to the product or service, then work to reduce and eliminate them.

Identify other sources of waste in the work environment. The seven original wastes are: overproduction, waiting, transport, extra processing, inventory, motion, and defects. This list of wastes and their definitions were developed to help teams recognize the various types of waste that exist in their operations. Ultimately it is not important to label each waste precisely according to their definitions; identifying waste for elimination is the primary focus.

In recent years, an eighth waste has been added to the list, the waste of underutilizing human potential, skill, and knowledge. This eighth waste is in keeping with the Lean theme of direct involvement in the work processes. The people who execute the process every day are best equipped to identify and eliminate waste, and should be heavily involved in the Lean transformation in their work area.

Kaizen teams utilize many Lean tools and techniques for eliminating waste. 5S is one of the most common and powerful techniques to organize and improve the efficiency of work areas. The 5S’s are: Sort, Straighten, Shine, Standardize, and Sustain. The first three S’s focus on clearing everything that is not needed from the work area, arranging and labeling all the items that are required in the area, and cleaning the work area and equipment. These activities free valuable space, remove improper items, and allow employees to see at a glance if everything is in its place. The last two S’s focus on sustaining the improvements to the work environment and rewarding the team by celebrating their accomplishments.

Once the work area is neat, clean, and organized, additional improvements in the forms of Workplace Design, Standard Work, and Visual Management techniques can be employed. Work flow can be improved using cellular workplace design techniques, which focus on arranging machines or office work areas into groups that produce a single family of products. Work cells are more efficient than traditional arrangements of machines or people grouped together into functional departments. Work activities should be standardized to ensure that everyone is doing the work consistently and in the most efficient way every time. Documentation of work instructions, quality or pass/fail criteria, operating instructions, 5S responsibilities, and other performance metrics should be posted throughout the work area so anyone working in the area immediately understands the current work status and operating expectations.

The quality and consistency of processes can be improved using Six Sigma or other quality improvement techniques. Defect reduction can be sustained by utilizing Poka-Yoke, or error proofing techniques. The goal of error proofing is to first prevent the occurrence of defects, and second to ensure that mistakes are detected when they occur. Because people can make mistakes even in inspection, error proofing often relies on mechanisms built into tools or systems that automatically signal when problems occur, or that prevent the process from continuing until the proper conditions are met. These types of systems prevent defects from being passed to subsequent operations and eliminate the need for separate inspection steps. Reducing defects also reduces the excess inventory required to prevent parts shortages due to quality fallout and saves time and resources spent processing defective product. That’s a lot of waste!

In a production environment, we cannot produce when equipment is down or not functioning at full capacity. Increasing equipment uptime is important to enabling product flow. Total Productive Maintenance (TPM) focuses on establishing processes to ensure that equipment is available by performing maintenance proactively rather than reactively. Similar to 5S principles, TPM relies on a clean work environment and operator training to identify and resolve minor equipment issues before they result in an unscheduled breakdown. Changeover reduction (also referred to as SMED, or Single Minute Exchange of Die) increases equipment uptime by reducing the amount of time required to change over between runs of different products. Similar to the concepts in Standard Work, changeover reductions focus on developing standard methods for executing the changeover, increasing the work steps that can be performed while the machine is still running, and decreasing the amount of work that can only be performed while the machine is stopped. When equipment is available and changeovers are short, the operation benefits from faster cycle times, reduced inventory, and more flexibility to run the products that are required.

All of these methodologies and concepts – waste reduction, 5S, Workplace Design, Standard Work, Visual Management, defect reduction, Poka-Yoke, TPM, and changeover reduction – are leveraged to develop processes that enable work to continuously flow through a stable and capable system.