Quality Function Deployment

The voice of the customer translated into the voice of the engineer.

To design a product well, design teams need to know what it is they are designing, and what the end-users will expect from it. Quality Function Deployment is a systematic approach to design based on a close awareness of customer desires, coupled with the integration of corporate functional groups. It consists of translating customer desires (for example, the ease of writing for a pen) into design characteristics (pen ink viscosity, pressure on ball-point) for each stage of the product development. Quality function deployment (QFD) is a tool that is sometimes referred to as the “voice of the customer,” or as the “house of quality.” Quality function deployment has been described as a process to ensure that the customers’ wants and, needs are heard and translated into technical characteristics. The technical characteristics are handled by the company through the design function, or better still, through a cross-functional team that includes sales, marketing, design engineering, manufacturing engineering, and operations. This activity should focus the product or service on satisfying customer requirements. QFD is a tool for the entire organization to use. It is flexible and customized for each case and works well for manufactured products and in the service industry. The possible benefits of using the QFD process are:

  • Creates a customer driven environment
  • Reduces the cycle time for new products
  • Uses concurrent engineering methods
  • Reduces design to manufacture costs (fewer changes)
  • Increases communications through cross functional teams
  • Creates data for proper documentation of engineering knowledge
  • Establishes priority requirements and improves quality

The goal of QFD is to translate often subjective quality criteria into objective ones that can be quantified and measured and which can then be used to design and manufacture the product. It is a complementary method for determining how and where priorities are to be assigned in product development. The intent is to employ objective procedures in increasing detail throughout the development of the product. The 3 main goals in implementing QFD are:

  1. Prioritize spoken and unspoken customer wants and needs.
  2. Translate these needs into technical characteristics and specifications.
  3. Build and deliver a quality product or service by focusing everybody toward customer satisfaction.

QFD was first applied in the Kobe shipyards in 1972 by Yoji Akao and his associates.  It met with great success and was introduced to the United States by Don Clausing in the mid-1980s. Various United States companies (mostly automotive) have applied the principles of QFD to their product design process. By using QFD,  Honda and Toyota were able to reduce the new product cycle time to two and a half to three years The U.S. carmakers were on a cycle time of five years (the late 80s to early 90s). QFD could be described as a concurrent engineering tool. QFD provides a graphic method of expressing relationships between customer wants and design features. It is a matrix that lists the attributes a customer wants and compares them to the design features (services that satisfy customer wants). The collection of customer wants and expectations are expressed through the methods available to most any organization: surveys, focus groups, interviews, trade shows, hotlines, etc. The house of quality is one technique to organize the data. The house of quality is so named because of the image used in its construction. The use of matrices is the key to the building of the house. The primary matrix is the relationship matrix between the customer needs or wants and the design features and requirements.

  • The left side of the house has the customer needs
  • The ceiling has the design features and technical requirements
  • The right side contains the customer priorities (comparisons)
  • The foundation contains the benchmarking, target values
  • The roof of the house contains a matrix describing the relationship between design features

QFD uses some principles from Concurrent Engineering in that cross-functional teams are involved in all phases of product development. Each of the four phases in a QFD process uses a matrix to translate customer requirements from initial planning stages through production control. Each phase, or matrix, represents a more specific aspect of the product’s requirements. Relationships between elements are evaluated for each phase. Only the most important aspects from each phase are deployed into the next matrix.

Phase : Product Planning:

Building the House of Quality. Led by the marketing department, Phase 1, or product planning, is also called The House of Quality. Many organizations only get through this phase of a QFD process. Phase 1 documents customer requirements, warranty data, competitive opportunities, product measurements, competing product measures, and the technical ability of the organization to meet each customer requirement. Getting good data from the customer in Phase 1 is critical to the success of the entire QFD process.

Phase 2: Product Design:

Phase 2 is led by the engineering department. Product design requires creativity and innovative team ideas. Product concepts are created during this phase and part specifications are documented. Parts that are determined to be most important to meeting customer needs are then deployed into process planning, or Phase 3.

Phase 3: Process Planning:

Process planning comes next and is led by manufacturing engineering. During process planning, manufacturing processes are a flowchart and process parameters (or target values) are documented.

Phase 4: Process Control:

And finally, in production planning, performance indicators are created to monitor the production process, maintenance schedules, and skills training for operators. Also, in this phase decisions are made as to which process poses the most risk and controls are put in place to prevent failures. The quality assurance department in concert with manufacturing leads Phase 4.


After setting the primary design characteristics “hows” from the house of quality can be converted to as the “whats” of another house that depicts detailed product design. This process is repeated with a process planning house and then production planning house. In this way, the voice of the customer is carried through from design to manufacturing.

While it is easy to get caught up in the process of constructing the house(s) and completing the entry of the data, one should not lose sight of the objectives of the house of quality methodology. Hauser  states that “The house of quality is a kind of conceptual map that provides the means for inter-functional planning and communications.” “The principal benefit of the house of quality is quality in-house. It gets people thinking in the right directions and thinking together.”

The voice of the customer, both external and internal, is quantified and presented in the format of a house of quality. The different organizational functional groups, engineering, marketing, manufacturing, and so on, are able to see the effect of design and planning changes in order to balance customer needs, costs, and engineering characteristics in the development of new or improved products and services.

The House of Quality

The first phase in the implementation of the Quality Function Deployment process involves putting together a “House of Quality” which is for the development of a climbing harness


Steps to the House of Quality

Step 1: Customer Requirements – “Voice of the Customer”

The first step in a QFD project is to determine what market segments will be analyzed during the process and to identify who the customers are. The team then gathers information from customers on the requirements they have for the product or service. In order to organize and evaluate this data, the team uses simple quality tools like Affinity Diagrams or Tree Diagrams.


Step 2: Regulatory Requirements

Not all product or service requirements are known to the customer, so the team must document requirements that are dictated by management or regulatory standards that the product must adhere to.

Step 3: Customer Importance Ratings

On a scale from 1 – 5, customers then rate the importance of each requirement. This number will be used later in the relationship matrix.


Step 4: Customer Rating of the Competition

Understanding how customers rate the competition can be a tremendous competitive advantage. In this step of the QFD process, it is also a good idea to ask customers how your product or service rates in relation to the competition. There is remodeling that can take place in this part of the House of Quality. Additional rooms that identify sales opportunities, goals for continuous improvement, customer complaints, etc., can be added.


Step 5: Technical Descriptors – “Voice of the Engineer”

The technical descriptors are attributes about the product or service that can be measured and benchmarked against the competition. Technical descriptors may exist that your organization is already using to determine product specification, however, new measurements can be created to ensure that your product is meeting customer needs.


Step 6: Direction of Improvement

As the team defines the technical descriptors, a determination must be made as to the direction of movement for each descriptor.


Step 7: Relationship Matrix

The relationship matrix is where the team determines the relationship between customer needs and the company’s ability to meet those needs. The team asks the question, “what is the strength of the relationship between the technical descriptors and the customer’s needs?” Relationships can either be weak, moderate, or strong and carry a numeric value of 1, 3, or 9.


Step 8: Organizational Difficulty

Rate the design attributes in terms of organizational difficulty. It is very possible that some attributes are in direct conflict. Increasing the number of sizes may be in conflict with the companies stock holding policies, for example.


Step 9: Technical Analysis of Competitor Products

To better understand the competition, engineering then conducts a comparison of competitor technical descriptors. This process involves reverse engineering competitor products to determine specific values for competitor technical descriptors.


Step 10: Target Values for Technical Descriptors

At this stage in the process, the QFD team begins to establish target values for each technical descriptor. Target values represent “how much” for the technical descriptors, and can then act as a base-line to compare against.


 Step 11: Correlation Matrix

This room in the matrix is where the term House of Quality comes from because it makes the matrix look like a house with a roof. The correlation matrix is probably the least used room in the House of Quality; however, this room is a big help to the design engineers in the next phase of a comprehensive QFD project. Team members must examine how each of the technical descriptors impacts each other. The team should document strong negative relationships between technical descriptors and work to eliminate physical contradictions.


Step 12: Absolute Importance

Finally, the team calculates the absolute importance of each technical descriptor. This numerical calculation is the product of the cell value and the customer importance rating. Numbers are then added up in their respective columns to determine the importance of each technical descriptor. Now you know which technical aspects of your product matter the most to your customer!


The Next stage

The above process is then repeated in a slightly simplified way for the next three project phases. A simplified matrix involving steps 1, 2, 3, 5, 6, 7, 9 & 11 above is developed. The main difference with the subsequent phases, however, is that in Phase 2 the process becomes a translation of the voice of the engineer into the voice of the part design specifications. Then, in phase 3, the part design specifications get translated into the voice of manufacturing planning. And finally, in phase 4, the voice of manufacturing is translated into the voice of production planning.
QFD is a systematic means of ensuring that customer requirements are accurately translated into relevant technical descriptors throughout each stage of product development. Therefore, meeting or exceeding customer demands means more than just maintaining or improving product performance. It means designing and manufacturing products that delight customers and fulfill their unarticulated desires. Companies growing into the 21st century will be enterprises that foster the needed innovation to create new markets.

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