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What is Lean Six Sigma?
Lean Six Sigma is a popular quality management approach that combines the concepts of Lean and Six Sigma.
Lean is the approach of improving process velocity and product quality by simplifying the value stream. It aims at identifying and eliminating activities and process that consumes resources but do not add value or serves any purpose.
Six Sigma is a quality improvement methodology that attempts to improve business process and products by limiting process variations or product defects to 3.4 defects per million opportunities.
Image by N. Nayab
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Both Lean and Six Sigma focus on eliminating waste and providing the best possible quality to products and services at lowest cost. The scope of these two methods however differs.
Lean is a continuous and on going activity that strives to change the culture of the organization and ingrain among the workforce the habit of relentlessly seeking out and removing waste across-the-board. The Lean culture reduces cycle times and streamlines processes, resulting in improved service levels, better productivity, optimal asset utilization, increased cash flow, right-sized inventory levels, shorter changeover times, better product designs, and reduced input costs. Lean however does little to improve actual process capabilities.
Six Sigma is a project-based methodology that aims to improve customer satisfaction by focusing on elimination of variation in a specific process. Six Sigma does not consider whether the process itself is per se a waste or not, and does little to optimize the process flow either. The impact of Six Sigma naturally remains confined to whatever the scope of the Six Sigma project.
The focus of Lean Six Sigma is to leverage the power of Lean and Six Sigma and improve productivity through quality improvements that eliminate variation, and through process re-design that reduce lead times, eliminate waste, and re-look inventory levels, all using analytical tools.
Lean Six Sigma also aims at empowering the workforce to manage change by involving them in the change management activity under the guidance of trained mentors. Traditional Six Sigma implementation team remains a closed group of green belts under the leadership of a black belt. Lean Six Sigma requires such a team, but also requires such team members to remain competent in Lean tools and also involve the entire workforce in the change management process. Again, Lean Six Sigma provides a definite quantitive and statistical basis for the implenentaion of hitherto pure Lean concepts.
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Lean drives change through overall delivery system whereas Six Sigma focuses more changing sub-processes.
One approach towards implementing Lean Six Sigma is applying Lean processes and tools to eliminate the wasteful and non-essential processes, and then applying Six Sigma DMAIC process to eliminate variation in the sub-processes that remain. Lean Six Sigma approach issues related to process velocity and eliminating waste such as excess inventory or lead-time issues using Lean tools such as 5S, poka-yoke and others, and approach issues related to quality defects such as reject, scrap, overall yield issues, or service errors using six sigma tools such as Analysis of variance (ANOVA) and other tools.
Another approach of Lean Six Sigma is adopting Lean tools in Six Sigma processes. The Six Sigma DMAIC methodology remains flexible to define defects and identify ways to resolve such defects. Lean Six Sigma ensures using Lean tools in such Six Sigma steps. For instance, the Improve phase of Six Sigma, aimed at improving the existing process to eliminate variation might adopt Lean tools such as FiveWhy’s, Five S, kanban, or poka-yoke to preempt defects.
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Focus on Lean Six Sigma in Your Organization
The success of Lean Six Sigma depends on good leadership with Six Sigma black belt and competent in Lean tools at the same time, a committed team of lean Six Sigma green belts who can take the initiative to herald the change and mentor others when the initiative permeates across the organization, and a good project charter that makes explicit the goals and focus of the Lean Six Sigma intervention.