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Tuesday, April 26, 2011

Introduction to Quality Function Deployment

Chapter 7 is the work of David Melton. David is an outstanding mechanical/thermal engineer, a highly experienced system engineer and executive manager. He has extensive training in Quality Function Deployment and years of experience putting it into practice. This chapter can be used as a stand alone guide for those desiring to use QFD as their primary systems engineering process or to augment more traditional systems engineering.

7        Quality Function Deployment (QFD) In System Engineering
7.0 Introduction
System development is a complex process. Bringing a product or system from concept through production, deployment (distribution) is generally called the Product Development Process. Consideration of product development as a process requires looking at a network of tasks that are necessary to bring the product to market and provide a product or system that fulfills the “Voice of the Customer “(VOC). The VOC represents a definition of the needs and wants of the customer. Regardless of how it is presented the product development process is exceedingly complex. It consists of numerous offs, shared responsibilities and interpretation of differences often resulting in conflicting priorities. A substantial body of technical knowledge must be employed (and deployed) often over a relatively long time frame, while experiencing constant resource changes. The product development process requires a great deal of communication and a substantial work effort from many different functional groups.  Product development can no longer be viewed as simply a Design Engineering Function.  Design Engineering is but one process of several interrelated processes and functions involved in developing a quality product. Ultimately the communication of information gets back to the customer in the form of a product/service. To minimize the risk and accomplish this effort successfully requires an effective communication and tracking tool and methodology.  The implantation of the QFD method can achieve this objective.
A system, however complex, must be carefully planned out to minimize subsequent redesign.  The full effect of inadequate planning (or understanding of relationships) is rarely detected until late in the development cycle or not until hardware is fabricated or code written.  The later any design change or design defects are detected the more time and money a redesign effort incurs. System Engineering is primarily about understanding relationships and interdependencies during system development. The System Engineering objective is to translate customer requirements to product(s) and service(s) that fulfill the customer’s needs. Systems Engineering has emerged as a distinct professional discipline in direct response to the increasing complexity of new development projects for all market applications.
Quality Function Deployment (QFD) is a systematic process for translating customer requirements into appropriate company requirements at each stage from research and product development to engineering and manufacturing to market/sales and distribution.  The output of the QFD process is a series of matrices that define critical parameters and requirements throughout the product life cycle.  A Product Life Cycle (PLC) is a sequence of stages that a product goes through from conception through design, production, distribution and final phase out, (commonly called cradle to grave)
The prime assumption underpinning system engineering is that a product should be designed to fulfill the customer’s actual needs. Self-evident as this approach may seem, it is surprisingly common for companies to develop products with little or no customer input or confirmation of perceived customer needs. Even when a large market exists, a product can fail when the customer's real needs are poorly understood or improperly deployed to the subsequent design process. The QFD process applied to hardware development is very similar and complementary to the recommended System Engineering (SE) process.  Much of the information generated by the QFD process is information needed to complete the System and Component specifications.  One added benefit that QFD brings to the SE process is a method for prioritization of requirements.  OFD also provides a method for identifying the critical design requirements (i.e. Cardinal requirements).  QFD provides a pictorial illustration of the System and Component Specifications and shows where requirements are allocated to the subsystems.
The QFD process is complementary and beneficial to decision making in the system development stage. QFD is a structured process to identify these relationships and determine which are most important in driving requirements and system development.  QFD generates the skeleton structure (architecture) for the system and subsystem specifications. When QFD is integrated into the system development process, it provides value-added information and knowledge to aid decision making while optimizing the product design
This section:
·         Defines QFD and how it can be integrated into the SE and System Development process to provide complementary benefits and aid decision making in defining and specifying a system.
·         Explains the benefits and features of using QFD in the System Development process.
·         Presents a simple structured system engineering approach to product development using QFD prior to detailed product design.
·         Focuses on the hardware development, but in general the concepts can be applied to software development to capture customer needs and requirements and flow requirements through algorithm development
Standard system engineering techniques have been defined in the United States (US) Department of Defense (DoD) and NASA for decades; and these techniques are also applied to large commercial products, e.g. in automotive and aircraft industries.  The health care sector has introduced QFD as a means to develop systems for health care. The QFD initiative in the US for hardware developed items follows a structured and disciplined process very analogous to the SE process defined by DoD. DoD SE methodology standardizes the flow-down and traceability of specifications for complex products from customer requirements through production, operation, and disposal. SE integrates all of the disciplines and specialty groups into a team effort forming a structured development process that proceeds from concept to production to operation.
The principles of system engineering using QFD span the entire life cycle of a product, but this chapter is concerned with the early feasibility and concept stages. Studies show that a large percent of the product's manufacturing cost is frozen at concept selection time. Many companies in all industries historically initiate product cost reduction efforts after the product is released to the production floor. If say, 85% of the manufacturing cost is frozen at concept development time, then post production release cost reduction is saving cost on 15% of manufacturing effort. The value-added return for the investment is likely to be low. Therefore, to make significant cost reductions, development effort must focus on the early concept selection stage where alternative concepts and technology are considered.
7.1 Background
The word quality in QFD has led to much misunderstanding. QFD was first introduced in most organizations through the Quality Assurance departments. In the QFD process several functional organizations other than the quality department are vital participants. Because the name can be misleading, QFD has been given a bad connotation. QFD is not a quality tool to audit functional organizations, rather it is a structured planning tool to guide and direct the product development process. Let us therefore not be resistant to the use of QFD because of the name, but rather seek to understand what QFD embodies.

Quality Function Deployment (QFD) is a translation of six Japanese Kanji characters:


As with any translation there is room for other interpretations. Each pair of the Kanji characters has alternate translations; Figure 7-1 illustrates these different translations. The most accepted interpretation is Quality Function Deployment (QFD).

  Figure 7-1 The Kanji characters for QFD have several alternate translations.

QFD has a broad meaning. It involves taking the features of a product driven by the customer's needs and evolving the product functions into an overall product. We may think of QFD as the act of taking the voice of the customer (VOC) or user all the way through the product development process to the factory floor and out into the market place. QFD is therefore more than a quality tool, but an important planning tool for introducing new products and upgrading existing products.

7.1.1 Features of QFD - As previously stated, QFD:
·         Is a systematic means of ensuring that the demands of the customer and the market place are accurately translated into products and/or services.
·         Is a structured approach that provides both a planning tool and a process methodology.
·         Identifies the most important product characteristics, the necessary control issues and the best tools and techniques to use. 
·         Applies to all stages of product development and provides a comprehensive tracking tool and communication medium.
·         Applies a cross functional team approach combining information and expertise from marketing, sales, design engineering and manufacturing.
·         Provides a systematic and disciplined method of creating priorities, making improvements, and defining goals and objectives applicable to the company's products and/or services.
QFD is a method; it is not a panacea, it must be done correctly and it takes up front time and resources to get the best possible results.
7.1.2 Benefits of QFD - QFD is a relatively simple but highly detailed process. Upon initial evaluation it may appear to be too detailed - perhaps not worth the effort. However QFD has proven benefits, including:
The QFD process leads the participants through a detailed thought process, pictorially documenting their approach. The graphic and integrated thinking that results, leads to the preservation of technical knowledge, minimizing the knowledge loss from retirements or other organizational changes. This use of QFD helps transfer knowledge to new employees, starting them higher on the learning curve. The use of QFD charts results in a large amount of knowledge captured and accumulated in one place. The charts provide an audit trail of the decisions made by the project team. Once a QFD project has been completed, the resulting charts may be used as a starting point for future versions, (a “re-engineering starting point”) for similar products. The bottom line of QFD is higher quality, lower cost, and shorter development time resulting in a substantial competitive advantage.
2.      SATISFIED CUSTOMERS; QFD forces increased understanding of customer requirements because it is driven by the voice of the customer, rather than the voice of the engineer or executive. By focusing on the customer, numerous engineering decisions are guided to favor the customer. Whereas numerous trade-offs are always necessary for any well optimized product, these trade-offs are made for customer satisfaction not for engineering convenience.
3.      FEWER START-UP PROBLEMS: The preventive approach fostered by QFD results in fewer downstream problems, especially at production startup.
4.      LOWER START-UP COST; This translates directly into reduced start-up costs
5.      LESS TIME IN DEVELOPMENT: This approach not only saves money, it also saves overall development time. Product introduction cycle time has been shown to be a third to a half shorter by using QFD to thoroughly plan the product or service.
6.      FEWER FIELD PROBLEMS; The cost savings has been demonstrated to continue well beyond startup, and is reflected in reduced problems for customers and consequent warranty cost reduction.
7.      FEWER AND EARLIER CHANGES; A major advantage of QFD is that it promotes preventive rather than reactive development of products.  QFD is a preventive approach that has demonstrated fewer downstream production problems; especially at production start-up; commonly referred to as “the transition from development to production”.

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