Types of Quality Control

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Your product is your business, so you must be sure that you manufacture and sell the best product possible. Doing that requires strategy, investment in time and money, and a commitment to quality. Quality control should be part of any business. It helps ensure that the product you sell is the best it can be. It also ensures that each product sold is identical so there are no variations in performance.

What Is Quality Control?

Quality control is the process that allows you to ensure the conformity of your products or services. It’s used to examine and test a product or service to make sure it meets the correct specifications and quality benchmarks. Through quality control testing, a quality inspector analyzes products, processes and other indicators using statistical analysis and sampling. Quality control monitors not only the product itself, but the way it is produced, stored and transported. When a product lacks conformity to quality standards, it is considered defective. Some quality control is voluntary, but sometimes quality control records must be kept for state and federal regulations.

Quality Control Tools

There are many approaches to quality control. The type you use depends on your specific product and should be determined before any quality control inspection begins. There are seven primary quality control tools which include:

  • Checklists. At its most basic, quality control requires you to check off a list of items that are imperative to manufacture and sell your product.
  • Fishbone diagram. This visual is helpful for determining what causes a specific problem, be it materials, machines, methods or manpower.
  • Control chart. This helps you see how processes historically change using controls. The chart helps you find and correct problems as they happen, predict a range of outcomes and analyze variations.
  • Stratification. Instead of looking at all factors together, stratification separates data so you can identify patterns and specific problem areas.
  • Pareto chart. This type of bar chart provides a visual analysis of problems and causes so you can focus on the most significant issues.
  • Histogram. A common graph that uses bars to identifies frequency distributions that indicate how often defects occur.
  • Scatter Diagram. Plotting information along two axes on this graph can help visually identify relationships between variables.

A quality control inspector uses one or more of the available tools or methods to do a complete analysis of a product or service to determine where improvements can be made. An inspector typically gets training to know what method to use and how to properly use it.

Internal vs. External Quality Control

Depending on the product you manufacture and sell, you may opt for internal or external quality control inspections. If you establish an in-house protocol to check your system, this is called internal quality control. It can range from routine checking of equipment, having a coworker go over another employee's data analysis or running standards and controls on a regular basis. It is generally up to management to decide if internal quality control measures are reliable and performed as needed.

When products or data are sent to an outside business not affiliated with your company, this is external control. One example of external control is in food production. A food company may routinely analyze the nutritional value or shelf life of a food item it produces in its own lab, but to verify the results, the same food item will also be sent to an outside lab. This verification by a third party is important to obtain Food and Drug Administration labeling and to prove to the FDA that the food company's production methods are sound.

References

About the Author

Leslie Bloom has worked in upper-level management positions in both publishing and the mental health field. In addition to years of business and management experience, she has more than 20 years of experience writing for a variety of online and print publications, including Metro Magazine. She holds degrees in both journalism and law.