Quality Function Deployment (QFD) is an approach and an effective planning tool to transform the "voice of customer" into a product, what meets both the stated and unstated needs of the customer. By using QFD, the supplier gathers inputs from the customer about its requirements and needs, and plans how to answer them in terms of design, development, manufacturing, service and communication. In other words, QFD is the interface between customer needs, and the reaction to them. Customers always have objective and subjective needs.

Japanese specialists started to invent and to use the methodology in the 60's, and it rapidly spread around the World, especially in the US and Europe. The pioneers of QFD were Mr. Yoji Akao and Mr. Shigeru Mizuno, publishing two major books about the topic:

On top of that, Mr. Akao founded the Quality Function Deployment Institute in 1993. QFD is an easily adaptable in any business field, but more often used in the automotive business. A new standard is under development in draft phase, of which its first part describes the principles of QFD:

ISO/DIS 16355-1: Application of statistical and related methods to New technology and Product Development process – Part 1: General Principle and Perspective of QFD Method.

So what is QFD in practice? According to the QFD Institute:

By hearing the voice of the customer, QFD not only lists, but prioritizes customer expectations, and serves as an effective tool, to:

QFD has its consistent principles and process in order to be able to translate needs into solutions. In case of product realization, QFD effectively complements APQP, and follows the principles of Simultaneous Engineering. QFD consists of four phases, the following table shows how customer needs turn into characteristics and processes.

Various matrices are used in each given phase. For example, the following matrix contains the product planning phase, where customer requirements are linked with product design (in the frame of the generally used House of Quality):

The following QFD matrix represents a given example about a premium flash-light, including four major requirements of the customer. In order to keep it simple, we have chosen only four customer requirements (customer needs), and four technical requirements (answer to the needs).

Description:

Section 1 - Customer requirements: starting the QFD by obtaining customer requirements in a structured way.

Section 2 – Priority rating means how relevant the given requirement is for the customer. This information can be gathered from many sources, but to get the voice of customer transparently, surveys, interviews and face-to-face negotiations are necessary. The scaling of importance rating is up to you, in the example point 1 means less important, while point 5 means the highest importance.

Section 3 – Competition analysis: as a complementary matrix of QFD, the competition analysis reflects the opinion of the customer about the competitors’ products, and shows our position in it. It helps to find where we are ahead of the competitors, and where we need to improve.

Section 4 – Technical requirements: the organization has to perform a brainstorming with the internal stakeholders to find what technical requirements need to be fulfilled in order to meet the customer requirements (e.g. if the customer wants to have a flash-light with very long battery life, we have to have a robust battery with high capacity). During the brainstorming it is strongly recommended to put all technical ideas on the board, and cluster them. In addition the participants must be invited from the core and from the extended team as well (including: design and development, manufacturing, sales, quality, etc.).

Section 5 – Relationship matrix: it helps to identify the interaction between customer and technical requirements. The relation can be strong, medium, weak or none (e.g. the relationship between "high luminosity" and "far throw" is very strong, however "waterproof" and "robust battery" has no relation to each other). You have to order numbers to the relationship, for example: 5 – strong, 3 – medium, 1 – weak.

Section 6 – Correlation: the top of the QFD helps us to find correlation between the various technical requirements, what were identified and clustered by the team. Such as before, here you also need to make a scale, which measures the correlation. The most current scaling is: strong positive, positive, negative and strong positive. An example: having a "lightweight" flash-light with "robust battery" is not easy to design, and the two factors have strong negative correlation, because as you grow your battery size (with the capacity), so you increase the weight of the product).

Section 7 – Importance rating: this section reflects the importance (weight) of the given technical requirements among each other. You can calculate the importance rating of the requirements by multiplying the priority rating and the relationship values one by one, and adding them. The rating itself represents how strongly the technical requirement affects the customer requirement, and by this how much it answers the given customer need if done right.

For example: the importance value of "Robust battery" is 47, which is equal to (5 x 3) + (4 x 3) + (4 x 5).

Section 8 – Technical difficulty: the QFD team determines how difficult it is to design and manufacture the product, what fulfils the given requirement.

Section 9 – Target values: in this section you can define exact values and specifications to the technical requirements (e.g. the flash-light must be able to throw light to 600 meters, or mustn’t be heavier than 700 grams).

QFD can be used not only in case of New Product Introduction (NPI), but also for many other purposes, such as:

QFD requires open communication with the customer during the collection of inputs, and intercompany team-work during the planning and design phases.

Not just listen to, but hear the "voice of customer". Understanding the needs at the beginning (planning phase) is crucial. If this does not happen, the project will surely fail, or will suffer a drastic time-delay (e.g. changing an improper concept or design in the later phases).

Complementing QFD with various techniques and tools is useful, especially in the automotive industry, such as:

At the first step of QFD, which is gathering inputs, use all available channels and sources:

When you are collecting inputs from your clients, consider, that your customer is not just the company, who orders shipments from you, but the end user as well. For example, if you are producing seats for the automotive industry, your customer is not just the OEM, but also the car user, who will surely have opinion about your product.

The most widely used QFD method is the House of Quality (HOQ), what links customer requirements and major product characteristics. Beside gathering information from customers, and important point of QFD / HOQ is to analyse the products of competitors, and the customers’ opinion about them.