Quality control is a necessary function of business operations. Companies may select from a variety of quality control methods to solve any problem, or potential problem. Most quality control problem solving methods are designed to prevent quality control problems or reduce the negative impact of quality control problems. Other quality control problems may largely be reactionary. Elements of different methods may overlap with other methods.
The quality assurance method prevents quality problems and isolates the problem quickly. Each step of the production process, from design to market, must under go inspection before moving to the next step. An independent or in-house quality control inspector may review the finish of each step to make sure that it meets specifications. The quality assurance process also involves an inspection of all raw material inputs before production. If a problem occurs, the company can review its quality assurance process to quickly identify missteps.
Consumer products require failure testing to expose weaknesses before sending products to the market. Failure testing is a proactive quality control problem solving method. Producers try every possible test to find a weakness in their product. For manufactured goods, products undergo repeated pressure tests, drops, spills and a variety of other everyday possibilities until the product breaks. Failure testing shows the strengths and weaknesses of the product which may reflect design, raw material or manufacturing quality problems.
Some quality control problems require a complete overhaul in the quality of the company. Failed products may be the result of an apathetic or untrained workforce, poor management, lack of documentation of the production process and weakness of the internal quality control process. The company management will revisit every aspect of the company, addressing the mission and purpose of the firm, providing on-site training to workers and changing the company culture to one that is concerned with quality at every level.
Companies understand that perfection is impossible, but those that employ statistical controls as a quality control method try to meet perfection anyway. Statistical control is a problem-solving method that employs the use of statistics to reduce the incidence rate of certain known problems. Mean calculations, control charts and range charts monitor customer complaints and returns continuously to ensure that a product stays within an acceptable statistical margin, such as 8 defects per million sold. Random testing is conducted on a percentage of manufactured goods to ensure that the statistical margin meets specifications. The company will redesign the product as necessary to ensure that its statistical goal is met.