Design Assurance for Engineers and Managers

John A. Burgess

• Publisher: CRC Press
• Year: 2020
• ISBN:
  9781000148756
• Edition: 1
• Topic: Tecnologia e ingegneria
• Subtopic: Ingegneria generale

This book describes the concepts and methods of a discipline called design assurance, and reveals many nontechnical aspects that are necessary for getting the work done in an engineering department. It is helpful to engineers and their managers in understanding and using design assurance techniques.

1 Introduction to Design Assurance

1.1 The Evolution of Controlling Product Quality

1.2 The Concept of Design Assurance

1.3 The Role of Engineering Management

1.3.1 Setting Policy

1.3.2 Giving Direction

1.3.3 Provide for Training

1.3.4 Monitor and Evaluate Results

1.3.5 Maintain the Pursuit of Excellence

1.4 Relationships with Other Disciplines

1.4.1 Marketing and Engineering

1.4.2 Purchasing and Engineering

1.4.3 Manufacturing and Engineering

1.4.4 Quality Assurance and Engineering

1.4.5 Accounting and Engineering

1.5 Starting a Design Assurance Program

1.5.1 Self-Examination

1.5.2 Think Big, Start Small

1.5.3 Follow-On Activities

1.6 Summary

1.1 THE EVOLUTION OF CONTROLLING PRODUCT QUALITY

For many years the control of product quality was considered a factory responsibility. It was largely a process of inspection—try to find the bad ones and separate them from the good ones. However, as mass production expanded, people began to realize the costs and inefficiencies of this approach were very high.

This awareness gave birth to a new and broader outlook on the management of product quality. Shortly after World War II various specialists in the quality control field developed the concept of Total Quality Control. It is based on the premise that quality must be considered and factored into every aspect of the product—from design through production and delivery. Under this approach, all facets of a business are integrated to achieve the desired levels of quality.

One of the major contributions of the Total Quality Concept is the recognition of the importance of preventing defects from happening. The old adage, "An ounce of prevention is worth a pound of cure," is especially applicable to modern industry. Detecting non-conforming or defective products is a difficult and expensive process. Even then, it is often only marginally successful.

A far better approach is to prevent the defects from occurring initially. This approach includes having the right requirements and the proper design as well as seeing the product is manufactured correctly.

In addition to the Total Quality Control concept, other means for enhancing the quality and effectiveness of product design have been developed over the past several decades. One notable effort has been cultivated by the American Society of Mechanical Engineers. In the 1920s and 1930s each boiler manufacturer designed and built his product according to their own methods and practices. Periodically, this resulted in boiler failures which caused extensive damage and loss of life. Finally a small group of engineers affiliated with ASME took it upon themselves to develop a standard set of rules and practices for all manufacturers to use. This led to safer designs, and the approach has been very successful through the years in dramatically reducing boiler and pressure vessel failures.

Many techniques are now being applied in industry to prevent defects from occurring in design and production. This focus on prevention has been a major contributing factor in the evolution of design assurance.

1.2 THE CONCEPT OF DESIGN ASSURANCE

Design Assurance, also referred to as Design Control, is a relatively new term in our industrial vocabulary. It has developed slowly from Drawing Control and expanded to cover all facets of product engineering activities.

For the purposes of this book, Design Assurance is defined as:

. . . those planned and systematic actions taken to provide confidence that the product design will satisfy the requirements of its intended use.

It is a response to the rapid advances in technology, increased complexity and growing sophistication in industry. No longer is it acceptable to rely on the "business-as-usual" methods and practices of years gone by.

The Design Assurance process is an outgrowth of management methods developed and used on military, aerospace and nuclear projects. Various quality systems were developed in the 1960s and 1970s to manage the process of achieving the proper levels of quality. Examples of these include MIL-Q-9858A, NASA NHB 5300.3, AEC-10CFR50 Appendix B, and ASME/ANSI NQA-1, Each of these program requirements documents contained provisions for controlling engineering activities.

Understandably, the application of special quality system requirements on engineering activities came as quite a surprise to many people. Always before, quality control focused only on the factory. Yet under closer examination, experienced engineers and technical mangers will recognize that most of the elements of Design Assurance are simply good engineering practices.

why then all the fanfare about some new discipline called Design Assurance? The best way to answer that question is with some real-life examples.

During the construction of a large nuclear powerplant, a major earthquake fault was discovered a few miles away from the powerplant site. After much investigation and analysis, it was concluded that additional seismic supports were required. The owner of the powerplant hired a competent engineering firm to do the redesign. The owner furnished a sketch of the plant arrangement which was to be used in the design project. However the sketch was "very sketchy." It did not contain all of the information that was required and, in fact, was based on some outdated drawings. However, the design group believed they had the correct information that was needed. As a result, the design work was accomplished, but it was not usable because it was based on incorrect input.

After the design work was finally corrected, the owner asked that the new design be applied to the adjacent, companion unit. However, the owner failed to tell that the companion unit was not identical to the first, but was a mirror image of it. Again the results were not usable until further corrections were made.

A medium-sized manufacturing firm produced a line of single and multi-stage pumps and enjoyed a strong market position in their industry. To the management's delight, they received a very large order for their pumps. However, the application required some development and modification of the standard designs. During the development phase, the engineers made a series of changes to the internal configuration. However, when the first new pumps went into production, several of the impellers cracked and broke during acceptance testing. After a detailed investigation, it was found that the structural analysis was performed on the next-to-last revision, but not on the final change The last modifications caused the structural limits to be exceeded, but no one realized the shortcoming until the pumps failed mechanically.

Another firm entered the microprocessor-controlled equipment area after many years of success as a builder of hydromechanically controlled equipment. Although the design and development efforts proceeded cautiously, the overall knowledge and skill of the design force was limited in the field of electronic controls. Considerable time and money was wasted as a result of inadequate technical review of the design. Many errors and oversights were made on matters which otherwise would have been found and corrected by qualified electronics designers. Finally, the management realized the shortcomings and obtained the necessary expertise for the program, and just in time to prevent a total disaster.

Now, to answer the earlier question: Why all the fanfare about Design Assurance? It is in recognition of the major impact that design has on the long-range well-being of a project, a product, or a producer, Today's consumers are much more aware of, and concerned about, the quality of the products they buy and use. Management now is realizing it is very difficult and costly to try to make a good product out of a poor design.

Errors or shortcomings in design are often hidden until the design becomes hardware. Even then, design problems may not show up until many units have been produced and are in operation. When a problem is discovered at this stage, it may be both expensive and embarrassing to correct. Yet, the penalties of the marketplace, and more recently of the courts, for failing to correct a problem, may be even worse.

Design Assurance is a response to these conditions. It is another management tool for running the business in an efficient and effective manner. And it should be management's responsibility. Several years ago, Dr. Juran, a prominent authority in the field of quality, found in his studies of industrial problems, that the workers cause or can correct only about 20% of the quality problems. The remaining 80% of the problems are caused by management, or are within their ability to influence or control.

Design Assurance is also a direct response to the need for defect prevention. Instead of allowing the product to get into production and then seeing if it will work, it is an approach for anticipating what can go wrong and preventing it from occurring. This also includes examining past designs and their problems and taking action for preventing recurrence of the old problems in the new designs. Do it right the first time is the theme of Design Assurance.

Design Assurance covers many traditional areas of engineering, such as drawing and specification control, but it also includes ...