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Deploying Lean

The automotive industry was under competitive pressure from Toyota to improve quality performance and reduce cost. The industry initially emulated some of Toyota’s operational systems embodied under the general term “Lean” and implemented the balance of them in 1990s. Lean systems optimize a process by matching its throughput to incoming customer demand using a takt time, and they simplify, standardize, and mistake- proof processes by eliminating non-value-add activities or waste, such as that associated with defects, unnecessary motion, unnecessary movement of materials, waiting, and other types of process waste. The result is an adaptable system with flexible cross-trained workers, reduced order-to- cash lead times, and reduced cost with higher quality.

Lean is effective for process improvement because people from the front office to the factory floor can use its simple but effective methods of work simplification, standardization, 5-S, cleaning local work areas, throwing out unneeded materials, value flow mapping, mistake-proofing, and others to analyze and improve their processes. 5-S is a particularly useful method. It is an acronym for sorting, simplifying, sweeping (i.e., cleaning the work area), standardization, and sustaining process improvements. 5-S and other Lean methods will be discussed in Chapter 6. The value of Lean for process improvement and significant productivity improvement is well documented after more than 50 years.

An integrated Lean system has several attributes. The first is problemsolving groups or continuous improvement teams. These enable organizations to improve quality by training workers to efficiently operate machines and other resources. Second, workers are trained to use simple tools to identify improvement opportunities. Performance measures and visual reporting are also key characteristics. Process simplification, standardization, and mistake-proofing help stabilize a process. Schedule stability is needed to match external customer demand to production using the takt time. A takt time calculation is done as follows: if daily external demand is 100 units and 500 minutes is available per day to produce the 100 units, the calculation would be 1 unit is produced every 5 minutes each day.

A process workflow is analyzed using value flow mapping (VFM). A VFM shows the interrelationships of operations within a process including its rework loops and wasteful work operations. Examples include the unnecessary movement of materials, setting up of jobs, processing of the work, inspection of work, storage of information or materials, and similar activities that do not add value. Value-add operations are those required by a customer, those that physically transform an object (physical or informational), and those that are done right the first time. In contrast, non-value-add operations are missing one of more of these characteristics. Note that processes transforming information rather than physical objects are analogous.

After the VFM is analyzed relative to value, the non-value-add operations are eliminated. A VFM has the practical effect of helping simplify a process the right way to reduce its complexity, cost, and lead time. It also shows ways to reorganize the physical layout of a process to further lower cost and lead time. Bringing operations in closer proximity and in a logical sequence reduces unnecessary movement between workstations and helps communication. As an example, using a U-shaped work cell enables easy balancing of production because workers can move within the cell to complete work tasks. If the volume coming into the work cell fluctuates

(with the takt time recalculated in these situations), it is easier to expand or contract the number of workers.

Design modifications are successively applied as a process is simplified, standardized, and mistake-proofed. Mistake-proofing ensures high process quality using inexpensive error warning and control systems. Depending on the process, TPM and single-minute exchange of dies (SMED) methods are implemented to further ensure process stabilization to maintain the takt time. External demand on a system can also be level- loaded to reduce its variability. Mixed-model scheduling will reduce lead time when product and process designs are simplified. Once a process is simplified and has a stable takt time, pull systems are implemented using Kanban quantities and standard transfer containers to control the flow of work. Kanban systems also help maintain stable inventory levels and aid in identifying process issues that impact the flow of a process. Finally, incorporating suppliers into the customer’s process helps reduce the variation of work flowing through the system, and such networks are integral to the long-term success of a Lean system.

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