Difference Between SPC and SQC

SPC vs SQC

While consumers have the last say on the whether a certain product meets their specific needs and quality specifications, manufacturers or producers make sure that their products are of good quality and fit for distribution.

Every manufacturing company has a department assigned on quality control, a process wherein all elements involved in the production of goods are reviewed to ensure that resulting products are free from defects. They use statistical processes such as SQC and SPC for this.

Statistical Process Control (SPC) is the process of overseeing and controlling how a product is produced using statistical methods in order to guarantee its quality and to ensure that the process produces uniform products at minimum waste.

The use of SPC started in the early 1920s for the purpose of improving the quality of manufactured products. It was later adapted and applied to processes other than manufacturing like in software engineering.
While traditional quality control checks the products after production either passing or rejecting a product basing on certain specifications, SPC checks the production process for flaws that may lead to unacceptable products.

It stresses on early discovery and prevention of problems by utilizing tools such as control charts, regular improvements, and designed experiments. This often leads to good-quality products, less waste, and less time spent to produce the product. It starts with knowing and understanding the production process through mapping out and frequent monitoring, determining variation causes using designed experiments and other tools and removal of special cause variations.

This allows quality engineers to see what, when, and where in the production process a change occurs so that they can immediately determine the cause of the variation or change and correct any problems that arise before they become unmanageable.

SPC is one of the three categories of Statistical Quality Control (SQC). SQC is a statistical method of analyzing variations in the manufacturing process in order to make it better and more effective. Only a certain number of samples are needed to determine whether the products are acceptable. It works by gathering important data from a specific sample size of a product being manufactured and utilizing statistics to determine the outcome of the process. Any data acquired from this can be used to develop and enhance the process.

Aside from SPC, the two other categories of SQC are descriptive statistics and acceptance sampling. Descriptive statistics is used to describe the characteristics and relationships of quality while acceptance sampling is the random inspection of products. With SQC, quality engineers can set acceptable limits on manufactured products.

Summary:

1.“SPC” stands for “Statistical Process Control” while “SQC” stands for “Statistical Quality Control.”
2.SQC refers to the use of statistical tools to analyze variations in the manufacturing process in order to make it better while SPC is a category of SQC that also uses statistical tools to oversee and control the production process to ensure the production of uniform products with less waste.
3.SPC checks the production process for flaws that may lead to low-quality products while SQC uses a specific number of samples to determine the acceptability of a product.

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