Quality Control and Quality Assurance | By QC Methods and Processes

Quality Control and Quality Assurance | By QC Methods and Processes

When looking for information on quality control, it can be easy to get confused. The terms “quality assurance” and “quality control” are often used interchangeably, but they actually have different meanings and should not be used in the same way.

• What is Quality Assurance (QA)?
• What is Quality Control (QC)?
• Quality Assurance (QA) vs. Quality Control (QC)
• If QA is Completed, is QC Still Necessary?
• Quality Control Methods
• The Quality Control Process

What is Quality Assurance (QA)?

Quality assurance is the process of planning and ensuring that production activities and requirements are fulfilled throughout the entire development and manufacturing process.

For example, in the production of a new high-end watch, QA would conduct watch research, evaluate watch design, analyze watch sales and business, and contact clients to determine specific requirements. During these processes, QA can anticipate potential problems that may arise with the watches and pre-define production processes and standards to prevent these issues.

What is Quality Control (QC)?

Quality control is a practical activity that involves inspecting and testing the products and production process to ensure that the finished products meet quality standards.

Continuing with the example of the new high-end watch production, QC would inspect the watches that have been produced and reject defective products, such as watches with scratches or those that have been painted the wrong color. These defective watches will then be reworked to ensure that the goods shipped meet your requirements.

Quality Assurance (QA) vs. Quality Control (QC)

To distinguish between QA and QC, their differences can be roughly divided into the following points.

Source: ANAR

1. Different Focus

Quality assurance (QA) aims to prevent quality problems before they occur in products, making it a proactive approach.

Quality control (QC) aims to find and reject defective products after problems have occurred, making it a reactive approach.

2. Different Orientation

QA arranges production activities and standards in advance and ensures they are followed throughout the entire development life cycle of the project. As a result, it is a line function that is process-oriented and relatively long-term.

QC inspects products during or after manufacturing, and only involves the testing phase of the life cycle. As a result, it is a staff function that is result-oriented and relatively short-term.

3. Different Function

QA can be viewed as a management tool that controls and guides the entire development life cycle to ensure product quality.

QC, on the other hand, can be viewed as a verification tool that finds and corrects defects before the product enters the market.

4. Different Responsibilities

QA involves communicating with various people and departments to ensure quality, thus requiring a larger team to handle different tasks.

QC, on the other hand, primarily involves product inspection and testing in the factory to measure quality, hence requiring a smaller team that specializes in product inspection and testing.

If QA is Completed, is QC Still Necessary?

When developing a new product, it is important to establish production plans and standards for quality assurance (QA) to ensure that these guidelines are followed throughout the project. However, to guarantee that the pre-defined processes and standards are accurately and completely followed, quality control (QC) is typically conducted after QA is completed.

QA is similar to making laws and regulations to prevent mistakes, while QC is like a policeman who catches mistakes when regulations are violated. If the pre-defined processes and standards are not followed, there may be issues with the product. QC measures the products to find and correct any defects, ensuring product quality.

Additionally, while not all sourcing projects require QA, nearly all require QC. If you are purchasing common goods, such as cups and bottles, or performing simple customizations such as adding a logo, having QC inspect the goods in different sourcing phases is sufficient.

Quality Control Methods

Quality control (QC) is an essential process to ensure that products meet your requirements and comply with regulations. How does it work? There are three common methods:

• Inspection: Inspect products or services based on specified requirements to ensure conformity.
• Testing: Test products, perhaps in a lab, when there are special safety and compliance requirements, such as CPSIA.
• Statistical measures: Uphold quality standards through measures like sampling, calculating probability, etc.

The most common method is product inspection. It can occur at each step of production to filter defects, analyze causes, and make improvements. The two general types of inspection most commonly used are 100% inspection and sampling inspection.

100% Inspection

When a product requires 100% inspection, each item is carefully checked piece by piece, including appearance, workmanship, function, safety, compliance, packaging, and more. This type of inspection is typically used for high-value products or those that require strict adherence to specifications.

Sampling Inspection

Sampling inspection, on the other hand, only tests a selected quantity of products. The inspection result will determine whether the entire unit is accepted or rejected. This method is commonly used at different stages of manufacturing quality control, as it can save time and money while delivering relatively reliable results.

Acceptable Quality Level (AQL)

AQL is the standard for sampling inspection. It provides guidance on how many defective products are considered acceptable. For instance, an AQL of 2.5 indicates a defective rate of around 5%. You can discuss the AQL with your supplier based on your products.

AQL has three general inspection levels (I, II, and III), with Level II being the most commonly used. Sampling inspection plans are created based on the AQL. If you tell the quality inspectors an AQL of 2.5, general inspection level II and a lot size of 80, they’ll help develop the final sampling inspection plan based on the two charts below.

onestopimport can assist you in quality control for your products. Our services include:

• $5 per man-hour cost with only one service fee.
• Support for 100% inspection and sampling inspection.
• Our focus is on the customer, not the manufacturer.

The Quality Control Process

To ensure product quality, each step from supplier selection to product warehousing may require quality control. There are typically four quality inspection types in the overall process. Depending on your products, suppliers, and costs, you can choose the inspection type that suits your needs. However, it is important to keep in mind that skipping any of the inspection stages before shipment may lead to loss due to flawed outputs.

Pre-Production Inspection (PPI)

Source: qualityinspection

As the name suggests, Pre-Production Inspection (PPI) is done before the actual production begins. This is especially important when you work with a new supplier or sign a large contract.

PPI can help you:

• Gauge the manufacturer’s ability to meet your needs.
• Ensure that the manufacturer understands your requirements.
• Verify if the supplier is ready for production.
• Obtain clear production schedules, such as production timelines and shipping dates.
• Assess the quantity and quality of raw materials and components.

PPI usually checks the following:

• Factory’s production lines and capabilities.
• Factory’s facilities and equipment.
• Raw materials and components.
• Prototypes and samples.
• The first product.

As the saying goes, a good beginning is half the battle. All of these can help you reduce the risk of supply chain disruption and save time and energy by minimizing later communication with your suppliers.

However, PPI has its limits. For instance, a deceptive factory may alter machinery or raw materials in the future production process, which PPI cannot inspect. In such cases, inspection during production might be more useful.

Need help with PPI? Submit a ticket here.

During Production Inspection (DPI/DUPRO)

Source: qualityinspection

During production, it’s common to conduct a DPI to ensure that your products meet strict quality and compliance requirements. This is especially useful if any quality problems were found during PPI. Typically, DPI takes place when only 10-15% of products are completed. This ensures that any quality issues can be promptly identified and resolved, avoiding delays and rework.

However, there is a range to consider when conducting a DPI:

• Under this range may consider checking too early. It’s important to avoid checking the first finished products as they are not representative of the average quality.
• Over this range may consider checking too late. Many factories in China engage in mass production, meaning that when 60% of the products are finished, another 30% of products are being produced. If you only conduct DPI at this time, any quality problems found may already have appeared in 90% of the products.

If most of the products require rework, the delivery time will be delayed and costs will increase. To avoid this, it’s best to inspect products at each key production process to ensure that the operation at each stage meets the requirements. For example, if you want to manufacture a metal box that requires injection molding and painting, it’s recommended to inspect each of the three stages to identify and solve any possible problems, such as mold size, assembly method, and painted color.

DPI usually covers:

• Production status during manufacturing
• Random sampling of semi-finished and finished products
• Timeline checking
• Package and packaging material checking

However, it’s important to note that PPI and DPI may not identify all hidden problems. Additionally, Chinese factories tend to complete labeling and packing at the end of production. Therefore, it’s recommended to follow DPI with a Final Random Inspection (FRI).

If you need assistance with DPI, please submit a ticket.

Pre-shipment Inspection (PSI)/ Final Random Inspection (FRI)

Pre-Shipment Inspection (PSI) is conducted on finished products when at least 80% of an order is packed and ready for shipment. Products are checked at random to inspect for defects according to standards and specifications. This is the final opportunity to take corrective action before products are shipped.

PSI usually covers the following areas:

• Quantity verification: Counting shipping cartons to verify the correct quantity.
• Conformity verification: Verifying size, color, weight, materials, marking, labeling, etc.
• Cosmetic and workmanship inspection: Sampling inspection to identify visible defects.
• Function and safety testing: Testing electrical safety, etc.
• Issuing reports for import and billing.

Amazon FBA Inspection is a typical pre-shipment inspection of goods shipped to Amazon. It is also conducted when the products are packed and ready for shipment. Your products have to fulfill the Amazon product checklist before they can be listed on the Amazon store.

Amazon FBA inspection can ensure that your products will not be rejected by the Amazon warehouse because of any Amazon FBA requirements. Also, it can help reduce the chances of receiving bad product reviews which may cause huge losses to your Amazon stores.

If you require assistance with PSI, please feel free to submit a ticket.

Container Loading Supervision (CLS)

CLS is performed before shipping when the finished goods are being loaded into containers at the factory. This process helps ensure that the goods are handled correctly and arrive safely at their final destination.

CLS benefits:

• Reducing the impact of transportation on the quality of goods.
• Avoiding damage to the goods caused by poor stacking.
• Saving costs by minimizing breakage and maximizing container space utilization.
• Verifying that the correct goods are loaded into the containers (no substitution).
• Checking the total quantity of products (no missing items).

Things that CLS usually checks:

• Container loading conditions (weather, arrival time, track number, etc.)
• Container condition (safety and cleanliness).
• Loading supervision (correct handling procedures).
• Product quantity and quality.
• Packaging and labeling (shipping mark, carton dimension, gross weight, etc.).
• Documentation verification (seal number).

Contact us for help with CLS.

Conclusion

We are a sourcing company with extensive experience in purchasing from China. We can help you with quality control during each stage of importing. We offer both sampling inspection and 100% inspection, at a low rate of $5 per man-hour. Our goal is to provide high efficiency and reduce the defect rate. Additionally, we do not charge for a second inspection if the first inspection result is a fail.

We not only inspect the goods but also communicate repair or rework solutions with suppliers. Please feel free to contact us and let us help you ensure the quality of your products. We are always on your side, not the manufacturers.