QFD and Six Sigma DMAIC

from the QFDI newsletter, January 2012

Efforts to standardize and strengthen product and process improvements are greatly welcomed in modern organizations, and nothing does it better than the DMAIC (define-measure-analyze-improve-control) approach in six sigma. This 21st version of Shewhart’s and Deming’s PDSA (plan-do-study-act) technique is the backbone of ongoing quality improvements in today’s leading companies.

The purpose of quality improvement is to eliminate the costs and losses associated with defects and deviations from targets. The process starts with defining those targets and how to measure them, and then determining what the current level of performance is. Next is to identifying the causes of why current performance fails to meet those targets.

Causal factors can be analyzed as those related to the 4 Ms, or those attributable to workers (men), equipment (machine), processes (method), or design (materials). Advanced thinkers may also include method of measurement (ex. poor gauging or measurement techniques), money (lack of funds to make desired improvements), and management (lack of top level support to invest in and support a quality culture). Let us know if you have identified other “M”s, please.

Once causal factors have been identified, data analysis helps focus on those with the strongest contribution to improving performance. Since DMAIC attends to current products and processes, data can be collected to statistically calculate the correlation between a causal factor and the undesirable effects of the defect.

Improvements to the undesirable effect are made by improving these highly correlated causal factors, and training workers, upgrades or better maintenance of equipment, new processes, or better design are investigated and tested. In addition to efficacy of these improvements, other feasibility constraints such as cost to implement, time to implement, etc. are considered in deciding what and when to implement.

Once the improvement is in place, standardization of the improvement is needed to prevent falling back to old ways. Thus, ongoing data collection helps control any deviations to the new process.

What Role Can QFD Play in DMAIC?

QFD has typically focused on new product development; the large time-consuming “houses” of classical QFD are considered overkill for addressing concerns with local problems associated with production or service delivery failures. Rather, QFD is an approach for identifying customer needs far upstream from production, even prior to design phases in order to define quality from a customer or user perspective and assure it is designed into the new product and quality assured during its build and delivery.