We all want to improve productivity in the plant, but that productivity has to be quality-driven. If mistakes and flaws increase at the same rate as productivity, that can hardly be called a win.

There’s a constellation of strategies for improving quality control (QC) and quality assurance (QA). Let’s shine the spotlight on Six Sigma.

What Is Six Sigma?

According to ASQ (the American Society for Quality):

Philosophy: The philosophical perspective of Six Sigma views all work as processes that can be defined, measured, analyzed, improved, and controlled. Processes require inputs (x) and produce outputs (y). If you control the inputs, you will control the outputs. This is generally expressed as y = f(x).

Set of tools: The Six Sigma expert uses qualitative and quantitative techniques or tools to drive process improvement. Such tools include statistical process control (SPC)control chartsfailure mode and effects analysis (FMEA), and process mapping. Six Sigma professionals do not totally agree as to exactly which tools constitute the set.

Methodology: This view of Six Sigma recognizes the underlying and rigorous DMAIC approach. DMAIC defines the steps a Six Sigma practitioner is expected to follow, starting with identifying the problem and ending with the implementation of long-lasting solutions. While DMAIC is not the only Six Sigma methodology in use, it is certainly the most widely adopted and recognized.

Ultimately, Six Sigma seeks to improve all business processes by decreasing process variation and increasing performance. The immediate goal is defect reduction, which then yields increased profits, improved quality of products or services, and a high level of employee morale.

Six Sigma Is Data Driven

This metric- and data-driven methodology has a stated quality performance goal of 3.4 defects per million opportunities (accounting for a 1.5-sigma shift in the mean).

Training in and emphasizing statistical thinking is critical to the Six Sigma philosophy.

Six Sigma certification recognizes three levels: A Certified Six Sigma Black Belt, trained in advanced statistics and project management, is the highest level, with Green Belt and Yellow Belt certifications in descending order.

Maintaining a focus on metrics is at the core of the philosophy. The acronym DMAIC expresses the Six Sigma approach to problem solving: Define, measure, analyze, improve, and control.

Building a Six Sigma Infrastructure

ASQ recommends initiating Six Sigma through specific projects to maximize the ROI from the time and money invested in Six Sigma training.

Instead of focusing on the individual tools, it is best when Six Sigma training provides a process-oriented approach that teaches practitioners a methodology to select the right tool, at the right time, for a predefined project. Six Sigma training for practitioners (Black Belts) using this approach typically consists of four weeks of instruction over four months, where students work on their projects during the three weeks between sessions.

Six Sigma: A Long-Term Process

Six Sigma is not an easy fix. Rather, it’s a philosophy and strategy intended to permeate an entire organization. It’s an iterative process which relies on studying data, realizing lessons via this analysis, and incorporating them into an ongoing implementation plan. The closed feedback loop thus crafted enables continuous refinement and improvement.