Demystifying The Difference Between Quality Control and Quality Assurance

Quality control, quality assurance & quality systems



What are quality management systems?


In order to determine the difference between quality assurance and quality control, it is important to understand two fundamental concepts.


For one, many people think that quality assurance and quality control are inherently the same process; in fact, even manufacturers often use quality assurance and quality control interchangeably. However, as this article will explain, quality assurance takes place upstream at the start of a manufacturer’s product development project, whereas quality control is carried out downstream during production or even post-production.


Secondly, quality assurance and quality control are actually part of a manufacturer’s complete, overarching quality system, also known as a quality management system (QMS). According to ISO 9000:2015: Quality management systems – Fundamentals and Vocabulary, a QMS is a set of business processes, methods, policies, documented information and tools that permeate an entire organization.


A QMS, when properly implemented, is designed to reassure—if not guarantee—that internal stakeholders, customers, supply chain partners, regulatory bodies and more that its products or services consistently meet quality requirements and comply with a specific market’s exacting standards.


A QMS is critical in helping manufacturers reduce their total cost of quality (COQ), which includes aggregated costs of preventing and rectifying poor quality. According to the American Society for Quality (ASQ), some manufacturers experience quality-related costs as high as 40% of gross sales—and many hover between 5% and 30%.

Unfortunately, as Quality Digest indicates, most executives believe that their companies’ COQ is less than 5% or, even worse, don’t know what it is at all.


Here’s an example: let’s say a manufacturer has $100M in gross revenue. If 20% of its revenues is impacted by poor quality, that is almost $20M a year—or around $77,000 per day in a workweek. That is a lot of money.


While quality assurance and quality control are fundamentally different, both play a huge role in reducing an organization’s COQ.

Now, let’s take a look at the differences between quality assurance and quality control.


What is quality assurance?


Quality assurance is a proactive process-based method to prevent quality control issues in products and services before they are developed and deployed. In sum, quality assurance can be viewed as a preventative measure.


Manufacturers implement quality assurance by defining and planning the quality assurance process, documenting it, selecting tools, such as checklists, to ensure it, and training staff accordingly.


Once the process is completely mapped and carried out, audits are normally also conducted periodically to validate that the quality assurance process is being respected and identify ways to optimize it.


What is quality control?


Quality control takes place after the quality assurance process has been defined. Contrary to quality assurance, which is based on a structure and effective planning, quality control is product- or service-based. The primary goal of a quality control process is to make sure there are no defects in a product or service and that quality requirements are being fulfilled.


In some ways, quality control can be perceived as being a more reactive method. The reason? While quality assurance plans for products or services to be of quality, quality control actually identifies and helps to correct errors in finished product/service before being rendered to customers. Quality control leverages comprehensive testing and inspections to monitor the quality of a manufacturer’s production output.


As you can see with the differences between quality assurance and quality control, if a manufacturer fully controls its quality assurance, fewer quality issues and costs will occur in the quality control phase. A tight grip on both quality assurance and quality control means less COQ—and a better bottom line.


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