Total Quality Control, Lean Manufacturing, Zero Defects, Total Quality Management, Total Productive Maintenance, Theory of Constraints, Six Sigma, are probably the best-known Quality Programs, but for those less involved, there may be some confusion between them. With this in mind, I made a historical summary with the main characteristics of each one.

TQC – Total Quality Control

TQC has one of its earliest origins, dating back to the development of statistical process control (SPC) techniques by American engineer Walter Shewhart in 1924. The main objective of TQC is to ensure compliance with product quality requirements. Armand Feigenbaum developed the principles of TQC while working at General Electric. He first introduced the concepts of TQC in an article in 1946, and then, in 1951, while already a doctoral student at MIT (Massachusetts Institute of Technology), he published his famous book Total Quality Control. The main points established and systematized by Dr. Feigenbaum were: new-design control, incoming-material control, product control, and special process studies.

Lean Manufacturing

Lean Manufacturing Probably the most popular of all Quality Programs, Lean was born in Japan, based on two concepts from the Toyoda family. First, Jidoka, conceived by Sakichi Toyoda (still for his loom factory), which advocated that the machine should stop when there was a problem, preventing defective products from being manufactured, so that the man could intervene and correct the problem. Later, in 1938 (the year after Toyota Motor was founded), Kiichiro Toyoda (founder and son of Sakichi) conceived Just-in-Time, which is a work philosophy that aims to combat waste. Later, the team was joined by engineer Taiichi Ohno, who developed Kan-Ban, a system of pulling material only when it is really needed (a system inspired by the supermarket model); and engineer Shigeo Shingo, an expert in manufacturing practices who, among other things, created Poka-Yoke, an error-proofing device that prevents the operator from performing a certain wrong action. Although Taiichi Ohno wrote several books on the Toyota Production System (or Lean Manufacturing), the best known seems to be the book “The Machine That Changed the World”, by James Womack, Daniel Jones, and Daniel Roos, published in 1990, which was largely responsible for the dissemination of Toyota’s production concepts.

TPM – Total Productive Maintenance

TPM comes from the acronym Total Productive Maintenance and was created in the 1960s by Nippondenso (now Denso Corporation), a Toyota supplier, which developed a system in which the operator himself was responsible for the simplest maintenance of the equipment. This gave the operator greater responsibility, since in the event of equipment failure, he would be the first to intervene, and therefore, he would also be more interested in taking care of the equipment. It was a paradigm shift that resulted in a reduction in time lost due to equipment downtime. Over time, the system developed and gained management features.

TQM – Total Quality Management

TQM (Total Quality Management) has its origins in TQC itself. The great names in this program were W. Edwards Deming and Joseph Juran, who went to post-war Japan to work to help rebuild the country’s economy, focusing on increasing the quality and productivity of the factories there, working to improve their projects and processes. Of Deming’s studies, his 14 management points are important, and Juran’s, the quality trilogy (planning, control and quality improvement), in addition to his 10 principles of quality-oriented management. One of the reference books on TQM is Deming’s Out of Crisis, published in 1982.

Zero Defects

Zero Defects is a quality program that aims to eliminate defects in the context of industrial production, but it does not mean that errors never occur, but rather that there will be no allowable error quota, and that the goal is to do things right the first time. “Zero Defects” has its origins in a study carried out by the American Department of Defense, which in 1968 published a technical report entitled “Zero Defects – The Quest for Quality”. This report is a set of articles that promote quality and the “Zero Defects” program, encouraging its use in the defense industry. In the early 1970s, Philip Crosby, then Quality Manager at Martin-Marietta (a merger of Martin Company and American-Marietta Corporation), a manufacturer of aerospace and electronic products, launched the “Zero Defects” program and its 14 steps for implementation, in addition to its fundamental points: compliance with requirements, the quality system must be focused on prevention (and not evaluation), the standard goal must be zero defects, and performance must be measured by the cost of non-quality. In 1979, Philip Crosby, now as vice president of the ITT conglomerate, launched the book “Quality is Free”.

TOC – Theory of Constraints

TOC is a concept that was introduced by Eliyahu Goldratt in his book “The Goal”, published in 1984. TOC advocates the elimination of constraints in the production process to increase its efficiency. Eliyahu was inspired by the analysis of Ford’s production line, which flowed until one of the work points was full, then interrupting the production flow. Eliyahu also observed Ohno’s work in the Toyota System and realized that the concepts that Ford introduced in his production process were not restricted to the mass production of a single product, but could be adopted in other production systems. TOC establishes that a production system is like a chain, which is as strong as its weakest link, that is, production will flow as much as the greatest constraint allows.

Six Sigma

Six Sigma Six Sigma is a process improvement methodology that establishes a quality standard equal to 3.4 DPMO (defects per million opportunities). It was developed at Motorola in the early 1980s, with its main articulators being engineers Bill Smith, who developed the statistical method for analysis, and Mikel Harry, who established the MAIC work plan – Measure, Analyze, Improve, Control (today, DMAIC, with the inclusion of the Define step). One of the most significant books on Six Sigma is Six Sigma: The Breakthrough Management Strategy Revolutionizing the World’s Top Corporations, published in 2000 by Mikel Harry and Richard Schroeder.

Of course, the topic of Quality is not limited to these 7 programs, as it is one of the broadest in the industry. However, these seem to be the main and most widely used. We chose not to include ISO 9001 in this comparison, because, although it is a quality management system, it is a standardization standard. Remember that quality tools have their benefits, but it is important that quality programs are introduced to solve a problem, and not to become a problem (read the article Why New Quality Programs Fail?).