In engineering and manufacturing, quality control and quality engineering are involved in developing systems to ensure products or services are designed and produced to meet or exceed customer requirements. These systems are often developed in conjunction with other business and engineering disciplines using a cross-functional approach.
Royal governments purchasing material were interested in quality control as customers. For instance, King John of England appointed a certain William Wrotham to supervise the construction and repair of ships. Some centuries later, but also in England, Samuel Pepys, Secretary to the Admiralty, appointed multiple such overseers.
The Industrial Revolution led to a system in which large groups of people performing a similar type of work were grouped together under the supervision of a foreman who also took on the responsibility to control the quality of work manufactured.
Quality Assurance has developed a good deal during the last 80-90 years (in about 20 year intervals) from its inception to the current state of the art.
During World War I, the manufacturing process became more complex, and foremen began to supervise large numbers of workers to ensure the quality of the work being produced. This period also introduced mass production and piecework, which created quality problems as workmen could now earn more money by the production of extra products, which in turn led to bad workmanship being passed on to the assembly lines.
Due to the large amount of bad workmanship being produced, the first full time inspectors were introduced into the large-scale modern factory. These full time inspectors were the real beginning of inspection quality control, and this was the beginning of the large inspection organizations of the 1920s and 1930s, which were separately organised from production and big enough to be headed by superintendents.
The systematic approach to quality started in industrial manufacture during the 1930s, mostly in the USA, when some attention was given to the cost of scrap and rework. With the impact of mass production, which was required during the Second World War, it became necessary to introduce a more stringent form of quality control which can be identified as Statistical Quality Control, or SQC. Some of the initial work for SQC is credited to Walter A. Shewhart of Bell Labs, starting with his famous one-page memorandum of 1924.
This system came about with the realisation that quality cannot be inspected into an item. By extending the inspection phase and making inspection organizations more efficient, it provides inspectors with control tools such as sampling and control charts.
SQC had a significant contribution in that it provided a sampling inspection system rather than a 100 per cent inspection. This type of inspection however did lead to a lack of realisation to the importance of the engineering of product quality.
For example, if you have a basic sampling scheme with an acceptance level of 4%, what happens is you have a ratio of 96% products released onto the market with 4% defective items – this obviously is a fair risk for any company/customer – unless you happen to be one of the unfortunate buyers of a defective item.
After World War II, the U.S. sent General Douglas MacArthur to oversee the re-building of Japan. During this time, General MacArthur invited two key individuals in the development of modern quality concepts: W. Edwards Deming and Joseph Juran. Both individuals promoted the collaborative concepts of quality to Japanese business and technical groups, and these groups utilized these concepts in the redevelopment of the Japanese economy.
Quality assurance covers all activities from design, development, production, installation, servicing and documentation. This introduced the rules: "fit for purpose" and "do it right the first time". It includes the regulation of the quality of raw materials, assemblies, products and components; services related to production; and management, production, and inspection processes.
Traditional statistical process controls in manufacturing operations usually proceed by randomly sampling and testing a fraction of the output. Variances of critical tolerances are continuously tracked, and manufacturing processes are corrected before bad parts can be produced.
During the 1980s, the concept of “company quality” with the focus on management and people came to the fore. It was realised that, if all departments approached quality with an open mind, success was possible if the management led the quality improvement process.
The company-wide quality approach places an emphasis on three aspects :-
The quality of the outputs is at risk if any of these three aspects is deficient in any way.
The approach to quality management given here is therefore not limited to the manufacturing theatre only but can be applied to any business activity:
It comprises a quality improvement process, which is generic in the sense it can be applied to any of these activities and it establishes a behaviour pattern, which supports the achievement of quality.
In manufacturing and construction activities, these business practices can be equated to the models for quality assurance defined by the International Standards contained in the ISO 9000 series and the specified Specifications for quality systems.
Still, in the system of Company Quality, the work being carried out was shop floor inspection which did not control the major quality problems. This led to quality assurance or total quality control, which has come into being recently.
The major characteristics, ignored during the search to improve manufacture and overall business performance were:
As the most important factor had been ignored, a few refinements had to be introduced:
If the original specification does not reflect the correct quality requirements, quality cannot be inspected or manufactured into the product.
To conclude, the above forms the basis from which the philosophy of Quality Assurance has evolved, and the achievement of quality or the “fitness-for-purpose” is “Quality Awareness” throughout the company.