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The Toyota Production System (TPS), also known as the Toyota Way or Lean Production, can be traced back to the 1950s, when Japan's post-war manufacturing industry saw double-digit growth fueled by the strong demand for industrial goods as a result of growing markets, both domestic and overseas, coupled with the Korean War.
Taiichi Ohno (1912- 1990), a production engineer who early on rose to one of Toyota's executives, is credited for systematizing the company's production management system. The pillar of TPS is an uncompromising pursuit for waste reduction (as characterized in the Lean Methods, Just In Time, and Kanban Systems) and a production system built on incremental improvements that repetitively outputs defect-free products (Kaizen, QC Circles, etc.). In Japan, the ruthless pursuit for waste and cost reduction is often dubbed by their suppliers and media as "wringing moisture out of a dry towel."
TPS largely concerns production and manufacturing activities. The story that Toyota's line workers are empowered to stop an entire assembly line when they discover a problem is the epitome of this approach. Interestingly, unlike many QC Circle stories that their blue collar workers and supervisors are encourage to report in annual conventions, one rarely hears about TPS by upper management or design engineers, although this could be something to do with the way the company guards its trade secrets.
When Drs. Akao and Mizuno developed QFD in the 1960s, many TPS techniques were already recognized as Japanese Total Quality Control (TQC) methods. What Akao and Mizuno set to achieve was a customer-focused New Product Development (NPD) system that captured and built in end user needs and quality requirements before manufacturing began. The name, Quality Function Deployment (QFD) , came from the fact that this new quality system aligns different organizational functions on a common goal of satisfying the customer. It requires cross-functional teams and departments to work together in incorporating customer needs from upstream NPD planning to production output and after-sales customer care.
In Comprehensive QFD, Akao systematized this approach to encompass every aspect of business and organizational management. It was the first quality system to directly link the operational quality (design and manufacturing designers, project members, sales staff, etc.) and management quality (R&D, Administration, Business Development and Planning, etc.). Through this aligned and linked approach, dots are connected and made visible across the divides of physical walls and organizational territories. This is why companies who have been doing traditional quality methods for many years and even Six Sigma are finding QFD quite useful in today's more complex business environment.
For example, at Kawasaki Heavy Industry (manufacturer of Japan's Bullet Trains, airplanes, industrial robots, etc), their traditional quality assurance activities focused on preventing recurrence of manufacturing quality problems. QC Circles on the plant floors, as touted in TPS, were typical of such efforts. Subsequent analysis revealed, however, that the majority of the quality problems reported after product delivery could be traced back to issues originating in the upstream processes such as Design, Contract, Procurement, etc.
The new revelation came as a shock to the company's management because they had been a leader in the zero defect movement and had been doing traditional quality control for many decades. "With so much quality efforts already taken, what are we missing? How can we make the engineers and contract administrators, who are in the forefront of the NPD process, see that they, too, need quality awareness? What tools can they use?" This turned the company's eyes to QFD in 1994.
Kawasaki began teaching QFD top down, beginning with the senior management level so they could support the efforts of downstream project teams. Over the years, the company expanded the QFD training to its engineers, managers, project team members, and eventually the front line hourly-waged factory workers and support staff. At the 1996 International Symposium on QFD, a Kawasaki presenter shared how all these QFD matrices became useful not only in planning the next generation products, but also in tracing back errors and deficiencies in the process, material, production, technology, and even communication in case of a post-launch quality problem.
In Reliability Deployment, methods such as TPS, FMEA (Failure Mode and Effects Analysis) and FTA (Fault Tree Analysis) are used to identify possible failure modes and preventive measures, with focus on compliance to engineering specs set for product functions and manufacturing / production processes.
For example, a Brazilian steel company made good use of QFD Reliability Deployment after the product was launched in the market and they received the first wave of complaint data from customers. Using the FMEA table, which nested in one of the House of Quality matrices, each characteristic of the product related to the complaints (low internal yields, in this case) was examined.
A negative Characteristic Deployment matrix was constructed. With this, a Fault Tree Deployment was produced for the entire process relevant to the identified characteristics. The weight of the characteristics was then recalculated, taking into account the customer complaints, internal yields, and the importance derived from the Quality Matrix. By crossing these matrices within a QFD framework, the company was able to understand the location of critical process issues with respect to quality. This FMEA exercise was later used locally to improve selected processes (the table above). Note, however, improper calculation of an RPN from ordinal scores is a separate issue.
In the 2003 International Symposium on QFD, it was reported that Japanese automakers had reduced the typical development time by 50% over the previous 8 years. As automakers face increasing global competition, wrong thinking about cost, i.e., carmakers' too much emphasis on cost reduction at the expense of suppliers' ability to maintain quality, could lead to quality problems including costly recalls, pointed out an automotive consultant from Japan.
He also warned to watch out for quality problems when new technology or new business methods are introduced: "Continued advancements in modularization have resulted in part and equipment suppliers being responsible for not only their products but also for new functions of those modules for which they are equipped." Add to that, "increasing computerization has contributed to products performing new functions or having new structures, and such rapid, radical changes to function and structure could raise new quality problems." He proposed using QFD to prevent such failures; below is one example of Design FMEA.
(Click for a PDF file showing the entire table)
Like Reliability Deployment, Comprehensive QFD also has a Safety Deployment. While commonly used in health and medical related QFD studies, it is important in manufactured goods as well. Common factors in safety deployment are hygiene, toxicology, automatic cut-off systems (to prevent run-away operation), electrical shock, traumatic injury, etc.
Given recent reports alleging safety issues in children's toys, automobile acceleration/braking, and others, QFD practitioners are encouraged to consider adding Safety Deployment.
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