Preface

In today's competitive market landscape, ensuring the quality of products and services is paramount for businesses to maintain their reputation, meet customer expectations, and achieve long-term success. For any engineering sector (manufacturing, construction, transportation, aerospace, food and agricultural products, oil and gas, etc.), product quality is a prerequisite for success. Quality control (QC) and quality assurance (QA) are two aspects of quality management. The American Society for Quality (ASQ ) defines QC as "part of quality management focused on fulfilling quality requirements", while it defines QA as "part of quality management focused on providing confidence that quality requirements will be fulfilled".

QC is basically the process of maintaining standards and ensuring product consistency. Its key objectives are detecting defects, identifying deviations, and maintaining quality standards. It comprises different techniques and tools, the main ones being statistical process control (SPC), inspection methods, and Six Sigma. SPC involves the use of statistical methods to monitor and control production processes. Techniques such as control charts, Pareto analysis, and process capability analysis help identify trends, deviations, and areas for improvement. The basic inspection methods in QC are visual inspection, measurement techniques, and non-destructive testing. These methods enable the identification of defects or irregularities in products or processes. Six Sigma is a data-driven methodology aimed at reducing defects and improving process efficiency. The DMAIC (Define, Measure, Analyze, Improve, Control) framework guides organizations through the process of identifying, analyzing, and eliminating variations in processes.

QC finds applications across diverse industries. In the manufacturing industry, QC techniques are integral to ensuring the quality and consistency of manufactured goods. By implementing rigorous inspection and testing procedures, manufacturers can identify and address quality issues before products reach customers. In software development, QC encompasses activities such as code review, testing, and debugging. Techniques like unit testing, integration testing, and regression testing help ensure the reliability and functionality of software products. In the healthcare sector, QC plays a crucial role in medical device manufacturing, laboratory testing, and patient healthcare services. Strict quality standards and regulatory requirements govern processes to ensure the safety and effectiveness of medical products and services.

QA focuses on the systematic planning, implementation, and monitoring of processes to ensure that products or services meet predefined quality standards. Its objectives include preventing defects, continuous improvement, and achieving customer satisfaction by delivering reliable and consistent outcomes. One of its foremost techniques and tools is quality management systems (QMS) that can be used for implementing standards such as ISO 9001 for consistent quality management. It is implemented through audits and reviews for regular assessments of processes, procedures, and

documentation. It also involves risk management, which consists of identifying, assessing, and mitigating risks to quality and compliance.

QA applications in the pharmaceutical industry include QA in drug development, manufacturing, and regulatory compliance. In construction engineering, QA processes can help ensure building codes compliance and structural integrity. In the software business, applicable QA methodologies may include agile testing, test automation, and regression testing.

QA provides two types of confidence: internally to the management of the engineering organization and externally to customers, government agencies, regulators, certifiers, and third parties. While QA involves how a process is performed or how a product is made, QC relates more to the inspection of the product. When QA and QC work in tandem, it leads to higher efficiency in the organization and to better products.

As QA and QC are quite interrelated and interdependent, many of the tools and techniques are used in both. These include, but are not limited to, checklists, quality standards and specifications, SPC, control charts, root cause analysis (RCA), Six Sigma, failure mode and effects analysis (FMEA), quality audits, quality management systems (QMS), continuous improvement (CI), Lean manufacturing, testing and inspection, and so on.

This book, *Quality Control and Quality Assurance – Techniques and Applications*, discusses the elements of quality, such as quality planning, quality control, quality assurance, and quality improvement. It includes topics related to QA, such as total quality management (TQM), failure testing, process and product quality assurance (PPQA), and SPC. It also presents QC modules including process control, control charts, acceptance sampling, and product quality control.

Covering some of the latest practices, techniques, and applications in QC and QA, the book is a useful resource for engineering and business professionals and students, managerial personnel, and third-party agencies.

We acknowledge the support of the editorial team at IntechOpen, especially Dominik Samardzija, Patricia Kerep, and Sandra Bolf.

> **Sayyad Zahid Qamar and Nasr Al-Hinai** Mechanical and Industrial Engineering Department, Sultan Qaboos University, Muscat, Oman
