Quality control is an ongoing activity done by every company to ensure that consumer demands and manufacturing standards are continuously met. Unreliable or defective products reaching customers without such routine and strict evaluation can be detrimental to the company’s public image in the long run. Quality control methods are a set of rigorous methodologies or predefined testing processes or steps with the ultimate goal of improving product quality.

Every company strives to deliver products on time without compromising on all quality aspects. Especially in the manufacturing sector where having well-defined quality control techniques that follow industry standards and best practices in place ensures a level of uniformity in the products manufactured.

Through robust quality inspection methods, a company can enhance customer loyalty, get repeat business and new customers from referrals, reduce product recall and improve its market position.
Quality control tools and techniques can vary based on the industry that the products belong to. These should also be in line with the standardized specifications or guidelines set by both national and international governing bodies.

There are two widely used quality control methods:

Method 1 – Quality Inspection 

Quality inspection involves physical inspection and activities, such as measuring, examining, testing or gauging the various characteristics of a product for comparing the results with predefined specifications or requirements. Quality inspection methods apply to components used for production, semi-finished goods and finished goods right before the shipment is done.

By doing a quality inspection, products can be checked physically for defects and if they meet the required quality standards. Quality inspection can include a pre-inspection method, process inspection and a 100% inspection method. Let’s take a detailed look into each of these stages used in quality control techniques:

Pre-Inspection Method

The pre-inspection method involves checking the raw materials when received by the manufacturer and before it goes into the actual production process. This early stage of inspection is especially useful when you want to make sure that only quality materials are used to produce the goods.

The quality control method is used to examine a product prototype or to determine the availability of the right tools in order to work with the delivered raw materials. Catching defects in raw materials itself can save the manufacturer’s time, costs and effort and prevent product recalls arising due to such defects.

Process Inspection

In manufacturing, a process inspection can happen at any point during the production cycle. Process inspection is done to ensure that the various parameters within each section of the process comply with industry standards. Inspecting the product before it gets to the final stage can help in the timely detection of errors or defects saving time and resources. Process inspection can vary based on the industry but these are usually done in three types of intervals:

  • Time-based Intervals – Possibly every 2 hours or 2 days based on the machinery.
  • Quantity-based Intervals – After a certain production volume is reached, say when every 5 units are produced.
  • Freely-defined Intervals – Done at any time depending on the management’s discretion.

100% Inspection Method

A 100% inspection method or full product inspection is when every product of the whole consignment is inspected for quality-related issues. The products are checked for meeting the set standards and the non-acceptable product units are separated. Corrective measures are then taken to avoid repeated mistakes in the product

The size or volume of finished products chosen for the 100% inspection method depends on the required degree of precision. The higher the accuracy degree, the larger the inspection sample will be.

Method 2 – Statistical Control

The statistical quality control method uses various statistical methods or techniques to check the quality of products. These quality control methods are widely used across industries such as food, pharmaceutical and manufacturing units. Statistical quality control methods can be done as part of the production process or as a last-minute quality control check or even as part of the final quality check.

Quality control is the best method to determine variations in products that are caused due to reasons like raw material, consistency of product elements, processing machines, techniques used and packaging applications. The statistical technique helps to detect errors at an early stage so reworks can be minimized.

The two types of statistical quality control methods are acceptance sampling and process control.

Acceptance Sampling

As the name suggests, in acceptance sampling, a sample product is checked for compliance with a predefined quality measurement to ascertain if it falls within the acceptable quality variation limit. Such variations in the product can occur as a result of unexpected or assignable causes.

With this quality control method, the number of defective products reaching the market can be reduced significantly. Acceptance sampling can also be employed to test the performance or efficiency of a product after it has been installed and to compare it with accepted industry standards.

Process Control

Another quality control method that falls under the statistical technique is process control. All activities employed to check whether a particular process is reliable and predictable and results in a consistent performance with the least amount of variation are what process control is all about. This method of statistical analysis can help to improve or control a process so as to achieve desired results.

This quality control technique is used across several industries like power generation plants, chemical processing, food and beverage industry, paper manufacturing and oil refining. The three types of process control methods are:

  • Batch process control – where exact quantities of particular raw materials are mixed for a precise period in a particular manner to achieve a specific product.
  • Continuous process control – where variables remain the same throughout to produce the product at the best economy, maximum flow rate and given composition.
  • Hybrid process control – that can include elements of both continuous and batch process control.

By partnering with a third-party inspection company like Global Inspection Managing, you can be assured that only the best quality control tools and techniques are used for quality control and quality assurance of your products. We operate on the specific guidelines set out in the regulations and legislations governing your specific industry. Our services ensure that businesses across the world are able to maximize their potential and maintain quality standards throughout their operation.