What is QFD?
Quality Function Deployment (QFD) is a design approach in which the
cross-organisational functions coherently and systematically maintain in
focus what is most important to customers and stakeholders, thereby
assuring quality and reducing time. We can apply QFD to any
project that, for one, is a development activity and, two, has a
definable customer. This includes products, parts, materials, services,
events, software and websites.
QFD is not a design and development process (even if the common model is
often depicted to resemble one). Its approach is a model for the
thinking and the collaboration that goes into identifying, prioritising and
resolving design problems. The QFD approach therefore integrates
different kinds of design and development processes.
Flow chart for product development, within which
the QFD approach is used.
(adapted from ISO 16355-1, Clause 5.2.2)
The founders have described QFD as “a way
to assure the design quality while the product is still in the design
stage” [Akao]. Standard ISO 16355-1:2015 on “General principles and
perspectives of Quality Function Deployment” defines it as the “managing of
all organizational functions and activities to assure product quality”.
The Standard tells that QFD assures satisfaction “by designing in […]
the requirements that are most important to the customer or
ISO 16355 does not provide any ready-made model for
implementing QFD. It defines a generic design process flow and describes how
the elements of QFD fits within the stages of this generic flow. Annex A to the standard informs of
example tools and summarily discusses a few recognised QFD model
By comparison to other more
established design and quality standards, ISO 16355 on QFD can be said to be in its infancy. In a sense, QFD
practitioners are still learners. The approach is continually evolving
and being tailored for individual circumstances. Judging by an internet
image search, the 4-phase model [by Clausing et al] is used in about 95% of all QFD
Example QFD models and their suggested areas of application, in respect
of project complexity (deducted from ISO 16355-1, Annex A). The 4-phase approach covers the majority centre range.
The 4-phase flow diagram shown here should be read as an generalised
approach. It is not a strictly delimited, sequential, process. When
designing a product feature, we
must of course give thought to how a chosen solution can be reliably produced.
We will apply Design For Manufacturing (DFM) principles and judge its fit
within our existing production systems. By time the product design phase
is complete, we will already know how to produce the design. The process
design phase is more about defining and refining the details,
including any process equipment, while keeping in focus the importance that tracks back to
the original Voice of Customer. Both the process design and operations phases may well
find design optimisation potential, which will benefit from an adjustment to
the initial design specification
[thoughts on the QFD model].
The 4-phase QFD model [from Clausing's] is a truncated variant of the
original ‘comprehensive’ approach [Akao].