Lean Six Sigma
From Wikipedia, the free encyclopedia
Lean Six Sigma is a business improvement methodology which combines (as the name implies) tools from both Lean Manufacturing and Six Sigma [1]. Lean manufacturing focuses on speed and traditional Six Sigma focuses on quality. By combining the two, the result is better quality faster [2].
This strives to mitigate significant failure modes of "Quality only" Six Sigma when it is applied to reducing variation in a single process step (sub-optimizing), or to processes which are not value added to the customer. The DMAIC steps can still apply, but the objectives ("Y's") and inputs ("X's") under study incorporate both quality (ppm) as well as speed (cycle time) metrics.
An example would be to add inter-process inspections to catch and eliminate defective units prior to further processing. The waste of processing defective units is eliminated, but at the expense of adding inspection which is in itself waste.
The first failure mode is partially mitigated by adoption of Rolled Throughput Yield analysis tied to cost [3], but is limited when costs are not tightly monitored at each process step.
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[edit] Typical application of Lean Six Sigma (simplified)
- Identify the processes (in a functional department or business) most important to delivering customer value.
- Map these processes using Value Stream Mapping.[4]
- Identify the bottlenecks / constraints in the value stream.
- Apply variation reduction through DMAIC/DMAD(O)V to standardize the relevant process steps.
[edit] An alternate application with DFSS
A further refinement is to improve understanding of customer value by use of Design For Six Sigma (DFSS) and Market based Management [5] tools
- Capture the Voice of the Customer using a Customer survey, Focus group, latent needs assessment, etc.
- Prioritize relative importance through Quality Functional Deployment.
- Apply the typical application of Lean Six Sigma as above to the highest priority functional inputs.
[edit] Who is using Lean Six Sigma?
Many companies such as Textron with mature Six Sigma implementations added lean manufacturing tools to the existing toolbox [6]. Others such as Caterpillar brought on consultants to develop a comprehensive program[7] Others such as Honeywell developed their own methodology upon a merger where one partner (Allied Signal) was mature in Six Sigma and the other in Lean [8]. And General Electric, developed Lean Sigma in conjunction with their Customer Satisfaction process (Net Promoter Score or NPS) to get the most benefit from DFSS and Lean [9].
