Lean Manufacturing

Six-Sigma

Six-Sigma is a rigorous, disciplined, data-driven methodology that was developed to enhance product quality and company profitability by improving manufacturing and business processes. Six-Sigma uses statistical analysis to quantitatively measure how a process is performing. That process can involve manufacturing, business practices, products, or service. To be defined as Six Sigma means that the process does not produce more than 3.4 defects per million opportunities (DPMO) – which translates to 99.9997% efficiency.

Six Sigma Concepts

The Six Sigma concept was developed by Motorola in 1986 with the stated goal of improving manufacturing processes and reducing product defects and variation. The underlying goal was to achieve near quality perfection with 99.9997% of variable values within specifications.

Building on earlier quality improvement methods, Six Sigma assumes the following:

1. Ongoing efforts to achieve stable, predictable process results are essential for business success
2. Manufacturing and business processes have characteristics that can be measured, analyzed, improved, and controlled
3. Sustained quality improvement requires commitment from the entire organization.

Six-Sigma Implementation

To achieve Six Sigma performance, the causes of manufacturing and business process defects and variation must be identified and eliminated. Two Six Sigma sub-methodologies were developed for this purpose:

1. DMAIC (Define, Measure, Analyze, Improve, Control) and
2. DMADV (Define, Measure, Analyze, Design, Verify).

1. DMAIC – DAMIC is used to improve existing processes that are below specification.

1. Define the projects, the goals, and the deliverables to customers (internal and external). Describe and quantify both the defect and the expected improvement.
2. Measure the current performance of the process. Validate data to make sure it is credible and set the baselines.
3. Analyze and determine the root cause(s) of the defects. Narrow the causal factors to the vital few.
4. Improve the process to eliminate defects. Optimize the vital few and their interrelationships.
5. Control the performance of the process. Lock down the gains.

2. DMADV- DMADV is used to develop new processes or products at Six Sigma levels. DMADV (alternatively known as DFSS [Design for Six Sigma]), can also be applied to existing processes that require more extensive improvement. [17]

1. Define: - Determine the project goals and the requirements of customers (external and internal).
2. Measure: - Assess customer needs and specifications.
3. Analyze: - Examine process options to meet customer requirements.
4. Design: - Develop the process to meet the customer requirements.
5. Verify: - Check the design to ensure that it's meeting customer requirements.

Borrowing martial arts terminology, a key innovation of Six Sigma was the creation of a professional quality management hierarchy. This structure works to involve all levels of the organization in the success of Six Sigma projects:

1. Executive Leadership includes the CEO and other top management
2. Champions, drawn from upper management, are responsible for Six Sigma implementation across the organization.
3. Master Black Belts, identified by champions or by executive leadership, function as in-house coaches, mentors, and trainers; 100% of their time is devoted to Six Sigma to ensure business and leadership alignment
4. Black Belts focus on the application of Six Sigma methodology to specific projects; 100% of their time is devoted to Six Sigma
5. Green Belts are involved with Six Sigma implementation along with other job responsibilities.

Lean Sigma is a current industry trend in which a process is made lean through efficiency improvements before Six Sigma is applied to reduce variation.

Lean Vs Six Sigma

Lean Manufacturing and Six-sigma are powerful philosophies backed by several tools for improving quality, productivity, profitability and market competitiveness for any corporation in a holistic manner. Lean Manufacturing focuses on eliminating waste and improving flow using various proven methods initially pioneered by the Toyota Manufacturing Company under the banner of the Toyota Production System (TPS). Six-sigma methods were first perfected by the Motorola Company and deployed with ferocious gusto by Jack Welch while he was the CEO of General Electric. Six-sigma is focused on reducing process variation using problem solving and statistical tools. An integrated approach to process improvement using lean manufacturing and six-sigma principles is required since both lean manufacturing and six-sigma are more of a cultural change meant to be the way a company does business rather than a one time tool to be used for quick improvement. Without a model to allow merging of the tools, companies will falter in search of a new quick-fix.