Requirements Management and Quality Functional Deployment
Table of Contents
“Ending up in the wrong place is the result of bad directions, not bad driving. Product failure in the marketplace results from errors in requirements, not implementation.”
- Thomas L. Musto, Chairman, IBM Corporation (Retired)
A definition of QFD: Quality-Functional-Deployment (QFD) [literal translation of the Japanese characters] is an analytical method to help you transform customer needs (the voice of the customer [VOC]) into engineering characteristics (and appropriate test methods) for a product or service by helping to create working definitions of customer requirements, which may be vague when first expressed. It allows the prioritization of each product or service characteristic while also setting product development targets for the product or service.
The QFD methodologies are designed to help engineers focus on new or existing characteristics of a product or service from the viewpoints of: customer needs, market segments, or technology-development needs. The technique yields charts and matrices.
I came to use QFD when HP was using it as a fundamental piece of its “Product Definition Process”. I attended a two-day QFD Course taught by the American Suppliers Institute (ASI) in 1989 (founded by Ford as the Ford Suppliers Institute and spun-off as ASI). This organization is now gone, replaced by the ASI-USA. They focus on Taguchi Systems and Design for Six Sigma. It is particularly useful in navigating the various phases of taking “Customer Needs and Requirements” down into the technical levels of “Technology Planning” and “Product”. QFD is an essential tool in customer-driven Product Plans and Roadmaps.
There are five important points to QFD which enable it to understand and develop products to suit consumers. It must be practical to produce and at the same time, to provide a competitive advantage:
• Understanding Customer Requirement
• Quality System Thinking + Psychology + Knowledge/Epistemology
• Maximizing Positive Quality That Adds Value
• Comprehensive Quality System for Customer Satisfaction
• Strategy to Stay Ahead of The Game
Identify the customer's vital requirements for the product or service and translate them into design requirements.
Develop a service blueprint of an elegant, effective, and efficient delivery process
Evaluate alternative designs
Implement the newly designed process for delivery of the product or service
The Methodologies of QFD can be quite involved, but are based on the seven parts of the “House of Quality” as seen in Figure 1:
1. Customer requirements
2. Importance Weighting & Competitive Evaluation
3. Technical requirements
7. Competition / Importance
The House of Quality (a simplification of the 7 part QFD House) is well explained by the Harvard Business Review article of May-June 1988 by John R. Hauser and Don Clausing.
The following is an excerpt from the QFD Tutorial-Webducate publication on the Web.
Figure 1. Elements of the House of Quality (HOQ) 
The first ‘house’ of the HOQ matrix to be completed is also the most important. It documents the “WHAT”, a structured list of customers’ requirements described in their own words (the Voice of the Customer). This information is usually gathered through conversations with customers. The list of customer needs documented in such an exercise must be prioritized before its entry into the HOQ. The use of an Affinity Diagram can be used to do this.
The Competitive Evaluation attached to the right side of the HOQ matrix serves several purposes. Firstly, it quantifies the customers’ requirement priorities and their perceptions of the performance of existing products. Secondly, it allows these priorities to be weighted based on the priorities that concern the design team. The metrics used in this section of the HOQ are generally gathered from customers using a questionnaire. The requirement Importance Weighting is the most important measure. This figure quantifies the relative importance of each of the customer requirements (described in the left-hand portion of the HOQ matrix) from the customers’ own perspective. The ‘weightings’ of the customer requirements can use the Figure of Merit (FOM) process to find their importance. This is also where these requirements are compared to a competitor’s performance.
This section of the HOQ matrix is also referred to as the engineering characteristics, the “HOW” or Voice of the Company. It describes the product in term of the company’s Core Competence. These engineering solutions are generated by the QFD design team who identifies all the metrics of the product which they understand are related to meeting the listed customer requirements. One additional row is often included, at the top of the matrix, to illustrate the direction of change in each of these variables.
This section forms the main body of the HOQ matrix and can be very time consuming to complete. Its purpose is to translate the requirements as expressed by the customer into the technical characteristics of the product. It will look like a two-dimensional matrix with cells that relate to combinations of an individual customer and technical requirements. Each member of the QFD team needs to identify where these interrelationships are significant.
The level of interrelationship (correlation) discerned is weighted usually on a four-point scale (strong, medium, weak, or none) and a symbol representing this level of interrelationship is entered into the matrix cell.
The triangular “ROOF” matrix of the HOQ is used to identify where the technical requirements that characterize the product, support or impede one another. As in the Interrelationship Section, the QFD team work through the cells in the roof matrix considering the pairing of technical requirements these represent. In using a Paired Ranking, the question is:” Does improving one requirement cause a deterioration or improvement in the other technical requirement?” When an engineering trade-off exists because of a ‘negative effect’, a symbol is entered into the cell to represent this (usually a cross or “-“). When two improvements support each other, an alternative symbol is entered into the cell (usually a tick or “+”). To indicate + / - interactions (e.g. strong / medium / weak) different colored symbols can be used. The roof matrix is important in that it points to where design improvements are supportive. It focusses attention to where the design improvement could lead to benefits to the product. Also, it focuses attention on the negative relationships in the design.
This section of the HOQ matrix summaries “HOW MUCH” the conclusions drawn from the data contained in the entire matrix and the team’s discussions. It is generally made up from two parts:
Technical Priorities – Each technical requirement of the product in meeting the customer’s specified needs are ranked. It can be calculated from the weightings and interrelationship matrix sections by multiplying the Interrelationship Weighting by the Overall Weighting. These values are then summed down the columns to give a priority score for each technical requirement.
Targets – A set of engineering target values to be met by the new product design is the final output of the HOQ matrix. The process of building this matrix enables these targets to be set and prioritized based on an understanding of the customer needs, the competitors’ performance and the organization’s current performance.
This is the final section of the HOQ matrix to be completed. Competitive Benchmarking – should be employed to evaluate each of the technical requirements. Metrics and important characteristics of the product should be measured both for the company’s own existing product and the competitors' products.
It is important to rank the relative technical position of the existing product. Also, it helps to identify the target levels of performance to be achieved in a new product.
Figure 2. The four ’House of Quality’ planning phases along with details of functions. [Source: ASI QFD Manual]
Uses and Benefits
The focus of QFD is, evaluating customer needs, creating innovative solutions and planning resources to make it happen. This process continues to a second, third and fourth phase as the “hows” of one stage become the “whats” of the next (Figure 2). Solder reflow thickness—a “how” in the parts house—becomes a “what” in a process planning house. Important process operations, like “squeegee pressure of the stencil screen producing the solder paste” become the “hows.” In the last phase, production planning, the key process operations, like “squeegee pressure of the stencil printer,” become the “whats,” and production requirements—knob controls, operator training, maintenance—become the “hows.”
TOOLS OF QFD
Written in the Industrial Engineering course 361 at Iowa State by Chen and Susanto (1998) , “Tools of QFD” are diagrams which are very useful for organizing the data collected and help to facilitate the improvement process. The diagrams can be used to display information about the degree to which customer requirements are being met and the resources which exist to meet those expectations. The diagrams QFD uses to organize information are known as the House of Quality.
In its broadest sense, the QFD House of Quality displays the relationship between dependent (WHATS) and independent (HOWS) variables (Woods, 1994) .
This House of Quality should be created by a team of engineers with knowledge of both company capabilities and the expectations of the customers. Team participation and discipline are required to effectively use the practice of QFD, which has proven to be an excellent team-building experience.”
Figure 3. A useful QFD Phase Diagram from C2C SolutionS 
Many templates are available for QFD users. Figure 3 from C2C SolutionS, supports several detailed QFD templates and tutorials.
Figure 4. The QFD / Roadmap Phases for the Printed Circuit Organization at Hewlett-Packard.
QFP in Printed Circuits
Figure 4 shows the QFD Methodology of the Printed Circuit Organization in HP. This proved extremely useful in helping HP Division innovate new products by unique PCB materials, processes or technologies!
QFD is one of the few methodologies that can translate customer technical requirements into parts, products or processes, which can be seen from the examples mentioned above. QFD does not replace the existing organization’s design process, but rather support’s an effective way of creating design objectives. It also helps to represent the customer’s voice into the production process to reduce costs. And, cutting production time is also very beneficial to the company.
Research shows that 42% or more of Japanese companies have adopted QFD to improve their quality, however, it is not widely practiced in the USA compared to Japan. In the future, QFD should be more adopted and practiced in the American manufacturing and service markets.
1. QFD Tutorial-Webducate, www.webducate.net/qfd/qfd.html
2. Chen, Chi-Ming, Susanto, Victor, Quality Functional Deployment (QFD), IE 361, www.public.iastate.edu/~vardman/ie361/s00mini/chen.htm
3. Woods, R.C., Managing to Meet Employee Expectations: Quality Improvement Tools Narrow the Gap Between Employee Expectations and Company Resources, Human Resource Planning Magazine, Vol. 16, No. 4, 1994
4. PDF by C2C Solutions; www.c2c-solutions.com
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