Quality Control in Manufacturing Basics: All You Need To Know

Quality control (QC) in manufacturing is a core concept that is the keystone for ensuring that products fulfill requirements and meet desired standards. These QC methods include a range of activities meant to regulate and improve production processes.

In this article, we will provide a detailed overview of various quality control procedures, key components of quality control systems, and the main benefits of such systems. Moreover, QC implementation in CNC machine shops is also discussed.

Contents
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I
What is Quality Control in Manufacturing?

II
Key Elements of a Quality Control System

III
Quality Control Methodologies and Techniques in the Manufacturing

IV
Which Tools Are Commonly Used for Quality Control?

V
Benefits of Quality Control Process in Manufacturing

VI
How Does a CNC Machine Shop Ensure Quality Control?

VII
Quality Control vs. Quality Assurance

VIII
How to Maximize Efficiency of Quality Control Procedures?

IX
WayKen Takes Strict Quality Control Process for Your Machining Projects

X
Conclusion

XI
FAQs

What is Quality Control in Manufacturing?

Let us begin by addressing the important question: what exactly is quality control in manufacturing? In general, quality control meaning refers to a range of organized methods and procedures implemented to ensure that products adhere to their specified quality requirements.

Quality control procedures involve testing and verification of production processes at several phases to identify defects or flaws in the product and rectify their potential cause if defects are recurring.

At the same time, there are several approaches to quality control management, each specifically designed for different aspects of manufacturing. Some target the improvement of production processes through process monitoring, some use statistical methods to identify and eliminate flaws, while some focus on the management and human aspects of production.

The importance of quality control in manufacturing is evident from the fact that one of the most well-known ISO standards is the ISO 9001 – Quality Management Systems.

Key Elements of a Quality Control System

A viable method for quality control in metal and plastic manufacturing comprises various elements that work together to produce consistent, high-quality products.

1. Inspection

Careful inspection of the product at multiple stages during its manufacturing process is essential to ensure that it meets quality standards. Inspection helps in spotting production flaws as they occur. This helps engineers identify faulty processes and bottlenecks, as well as prevent subpar products from making it to subsequent manufacturing processes.

2. Testing

Testing goes beyond simple visual inspection. Instead, it extends to a variety of methods meant to examine a product’s performance. These can include mechanical testing, chemical examination, failure analysis, or other product-specific analyses that give engineers crucial information on whether a product can operate in its defined working conditions.

3. Documentation

A strong quality control system has well-defined guidelines for maintaining documents like inspection records, quality standards, calibration certificates, institutional hierarchies, etc. SOPs related to these not only include just the documentation but also the people responsible for them as well as a schedule for updating them.

Proper documentation facilitates a smooth flow and easy availability of information in production environments. It also encourages accountability and serves as an official proof of the work done in audits and regulatory compliance meetings.

4. Monitoring Systems

After establishing product standards and process guidelines, it is necessary to monitor how well they are being followed. In advanced manufacturing environments, continuous monitoring checks are performed to catch process deviations in real time to mitigate problems.

Some of the common monitoring methods include routine manual checks, regular stock counts, part quality inspections, and computer vision-based techniques for catching defects.

5. Corrective Action Plans

When non-conformities occur in a production process, a well-defined corrective action plan is a key guideline for personnel on how to address and resolve the issue. Correction action plans define the exact measures to be taken to correct problems, prevent recurrence, and improve quality all around.

6. Continuous Improvement

Continuous improvement is more a management philosophy than a hardcore process. It involves constant, never-ending efforts to enhance production quality, reduce waste, and boost productivity.

Various strategies such as lean manufacturing, kaizen, and Six Sigma are widely used to cultivate an environment of continuous quality enhancement in manufacturing organizations.

Quality Control Methodologies and Techniques in the Manufacturing

A wide variety of quality control methods are employed in the industry to ensure that production processes run smoothly. In the sections below, we will discuss some of the most popular quality control measures.

100% Inspection Method

The 100% inspection method involves checking each item in a production batch. This technique is usually beneficial in high-security requirement industries like aviation where there is low tolerance for mistakes. Moreover, it is also applicable to small-scale custom manufacturing projects where each product requires individual quality checking.

As the method is extremely thorough, it requires time and resources to execute, making it impractical for the mass production process.

Lean Manufacturing

Lean manufacturing is a customer-centric production strategy that strongly emphasizes cutting waste and pursuing continuous process improvement. It is a unique quality control process as it focuses on waste rather than value addition.

The lean experts map the entire value-addition chain of a production process and then focus their efforts on improving the low-performing ones. Nowadays, lean manufacturing has been widely adopted as a quality control management strategy across the board including industries like aviation, automotive, medical, and construction.

Six Sigma

Six Sigma is a data-driven approach that aims to limit defects and process variation below a certain level. To be exact, the goal of Six Sigma is to have just 3.4 defects per million opportunities.

It requires an in-depth analysis of the production process to identify possible opportunities for defects to occur. Since this quality measure applies to the entire process, the quality team automatically focuses on fixing the most defective areas.

Total Quality Management

Total quality management is a holistic quality control approach that strives for long-term quality improvement. It emphasizes continuous improvement through management principles that involve every person from top management to production floor personnel.

This organization-wide implementation allows every individual to participate in quality control measures, which maximizes efficiency and boosts employee morale.

Statistical Methods

These methods use various statistical tools to manage and control production processes. Statistical methods help production managers quantitatively analyze their processes and actions, putting them in a better perspective for decision-making. Here are some of the statistical techniques production managers use:

• Statistical Process Control: Data from production sites is used to statistically distinguish abnormal events from normal procedures. In the case excessive deviations are detected, corrective measures can then be taken to avoid flaws in the product.
• Design of Experiments: An experimental approach where several experiments are conducted to gain a better understanding of how different variables/inputs affect a process. There are numerous techniques like the Taguchi method to minimize the number of experiments while preserving information gain.
• Sampling: For inspection, testing a representative sample of products is more feasible rather than the complete batch. The ideal sample size and composition can be statistically determined. This method of sampling makes quality control in manufacturing more efficient than the 100% inspection method.

These statistical quality control examples illustrate a variety of tools manufacturers use to maintain and enhance product quality. By choosing the right approach for their industry, manufacturers can reduce errors and increase efficiency.

Which Tools Are Commonly Used for Quality Control?

Quality Control in manufacturing involves the use of multiple tools that go hand in hand with the different methodologies we discussed above. These tools play a fundamental role in helping production engineers realize their quality control goals.

1. Control Chart

Control charts are Statistical Process Control (SPC) tools that help monitor variance in the production process over time. These charts help in the identification of trends, shifts in these trends, or any unusual deviation in the production process.

The most common types of quality control examples charts include X-bar, R-chart, and P-charts.

2. Check Sheet

Check sheets are a generic tool for quality control in manufacturing that helps ensure compliance with standard procedures and standards. They are an easy-to-read visual log of production activities, making them a great resource of preliminary data for creating histograms and other visual aids for decision-making in quality control.

3. Cause and Effect Diagram

Cause and effect diagrams (Ishikawa or fishbone diagrams) are quality control tools useful in evaluating the basic factors (or causes) leading to a production defect (of effect).

Mapping all the possible sources of a recurring problem makes it simpler to establish causality and focus on only the most probable causes.

4. Histogram

A histogram is a graphical representation of the frequency distribution of variables in a data set. While seemingly a very simple diagram, it is a powerful tool for quality control in manufacturing as it allows to quickly interpret the gross patterns and variation in their production data.

5. Pareto Chart

Pareto charts are based on the classic 80/20 rule, which states that 80% of consequences come from just 20% of the causes. A Pareto chart uses bar and line graphs to highlight the most significant causes of production problems, guiding engineers to focus their efforts on areas that matter the most.

6. Scatter Diagram

Scatter diagrams express the correlation between two variables in a comprehensible way. It is easy to identify inherent trends, outliers, and irregularities in production floor data by looking at a scatter diagram.

In addition, for quality control in manufacturing, scatter diagrams are helpful in identifying cause-and-effect relationships.

7. Stratification

Stratification analysis is a technique that sorts data into separate categories based on some predefined criteria. It can help in identifying hidden trends in manufacturing data and catch flaws that are not easily visible through visual aids like histograms or scatter diagrams.

Benefits of Quality Control Process in Manufacturing

Quality control in manufacturing is significant for justifying business viability. Its proper implementation in a production environment carries numerous benefits for stakeholders including investors, consumers, and employees.

Improved Product Quality

The core purpose of quality control is to ensure that the product consistently meets its specified quality standards. By using quality control tools, a manufacturer can reduce the product’s defects and variations, and its overall quality rises. This, in turn, pays consistent dividends to the company.

Cost Saving

Poor quality control in manufacturing and financial loss go hand in hand. The risk of expensive recalls and reworks is quite costly, and it can be significantly reduced by implementing quality control techniques.

Moreover, quality control methods also streamline overall operations, decreasing material waste and improving inefficient processes. These factors lead to indirect cost savings as well.

Enhanced Customer Satisfaction

Customer satisfaction is what keeps people in business. Quality control reduces product faults and decreases costs, making them more reliable and affordable for customers to prefer over competing products.

Compliance with Standards and Regulations

There are heavy regulations on the manufacturing industry by quality standards and environmental protection laws. Implementing extensive quality control procedures enables companies to ensure compliance with these standards and regulatory requirements.

How Does a CNC Machine Shop Ensure Quality Control?

A CNC machine shop is the ideal case study to discuss quality control examples. The CNC machining facility generally consists of CNC machines like CNC milling, CNC lathe, EDM, CMM, etc., hires multiple staff members, and deals with a variety of materials. This means that there are several ways a machine shop may be inefficient, which is why rigorous quality control is a necessity.

In this section, we discuss a few key quality control strategies relevant to CNC machine shops.

Lean Production

Several types of waste can occur in CNC machine shops. Lean manufacturing principles are fundamental in identifying and removing these wastes. For example, idle machine time can be minimized by defining a better workflow of materials and resource allocation.

Similarly, targeted quality control measures like the 5S methodology are quite useful in standardizing and organizing the production floor layout of CNC machine shops. This ensures workspace cleanliness and quick access to machinery, tools, and documentation.

Tool Calibration and Maintenance

CNC machine shops have numerous precision equipment like CNC machines, tool holders, and measurement equipment (surface testers, dial gauges, microscopes). Moreover, cutting tools are subject to frequent wear and tear, thermal loads, and breakage.

Regular calibration and maintenance of these items help maintain consistent production standards.

In-Process Inspection

Real-time monitoring of machining operations allows operators to detect and correct deviations on the spot. One of the quality control examples for this is the use of probing devices for real-time testing of dimensional accuracy.

These programmed probes automatically apply adjustments to work coordinates and cutting tools in the G-code whenever they sense any deviation in the dimensions.

Documentation and Traceability

Maintenance of detailed documentation is one of the basics of quality control management. Having a record of production activities ensures traceability and accountability in the future. This helps in detecting and resolving issues quickly.

Another application of documentation is in inventory management. CNC machine shops often have thousands of different tools, holders, inspection equipment, fasteners, etc. in storage which are impossible to track without professional documentation. Therefore, quick and easy access to these items improves time management and production quality in CNC machine shops.

Quality Control vs. Quality Assurance

Quality Control (QC) and Quality Assurance (QA) are both crucial components of a Quality Management System (QMS). Although they are both quality-related concepts, they differ in their fundamentals.

Quality Control is a product-oriented approach that focuses on detecting and correcting defects in the finished part. It comprises techniques such as inspection and testing to ensure that the product meets the required quality. Quality control methods apply at multiple stages of a manufacturing process, with the common objective of ensuring minimal deviation from established systems.

Quality Assurance is a process-oriented proactive approach that focuses on preventing any defects in a product before they occur. It aims to design production processes at the organizational level to minimize the chances of defects and deviations occurring.

It can be said that quality assurance is a bigger picture concept than quality control in manufacturing. Together, QA and QC collectively work to guarantee optimal quality management of manufacturing processes.

How to Maximize Efficiency of Quality Control Procedures?

Maximizing the efficiency of quality control in manufacturing requires implementing strategies focusing on both prevention and detection. Following are some suggestions that can be incorporated into quality management systems for maximum performance.

Automation and Technology

Businesses can yield significant results by incorporating the use of technologies like AI and data analytics in quality control management. Some companies use computer vision to detect visual errors like surface cracks or form tolerances by training machine learning models on their end products.

Process Standardization

Standardization of production processes makes them less susceptible to variations. People know what to do, the machinery is programmed for its standard tasks, and a smooth flow of materials is ensured through the value chain. For example, the maintenance of a standard temperature in CMM rooms helps avoid dimensional variations due to changes in ambient temperatures.

Integrated Quality Management System

It can be challenging to integrate quality control technologies with the production process because of the initial investment and developing know-how of the technology, but it pays heavy dividends. In a modern CNC shop, an example of this can be using real-time force monitoring to monitor tool wear.

Training and Up-skilling

A skilled workforce can be fundamental in implementing quality control right at the shop floor level. For instance, the efficiency of implementing and maintaining a 5S initiative on your shop floor can be greatly enhanced by teaching your workforce about the benefits of maintaining a clean and neatly organized shop.

Allowed Continuous Improvement

Continuous improvement keeps you in business. When employees at all levels are allowed to voice their opinions on quality control matters, it can make a huge difference. By giving these operators a system to communicate machine errors early on, a lot of money can be saved through preventive maintenance.

WayKen Takes Strict Quality Control Process for Your Machining Projects

WayKen Rapid Manufacturing is an expert providing a range of machining services in engineering and manufacturing. We take In-Process Inspections for every single part, and Final Inspection to ensure machined parts conform to quality standards. In addition, we have advanced inspection machines, including ZEISS and KEYENCE, to meet the requirement of high precision and strict quality control.

Choose WayKen as your trusted rapid manufacturing company, we can provide you with high-quality parts and final products.

Conclusion

A solid quality production management system can be a real game changer in the manufacturing industry. Manufacturers can distinguish themselves from the competition by having a proper mindset and plan for quality control in manufacturing.

FAQs

What roles are included in quality control?

Multiple professionals partake in quality control processes. These include quality inspectors, production managers, QA engineers, data analysts, and process improvement specialists.

Who is responsible for quality control in the machining process?

In a typical machine shop, the professionals directly involved in quality control generally include the machinist, production supervisor/manager, and quality inspector.

What are some common challenges in manufacturing quality control?

The common challenges in manufacturing quality control are human errors, equipment calibration, real-time data analysis, variability in the quality of raw materials, and the handling of large amounts of data.