DXF

DFX, or design for X, can be defined as a knowledge-based approach that attempts to
design products that maximize all desirable characteristics—such as high quality, reliability,
serviceability, safety, user friendliness, environmental friendliness, and short
time-to-market—in a product design while at the same time minimizing lifetime costs,
including manufacturing costs.
Historically, designers have tended to underemphasize or overlook the preceding
factors and have concentrated their efforts on only three factors: the function (performance),
features, and appearance of the product that they develop. They have tended
to neglect the “downstream” considerations that affect the usability and cost of the
product during its lifetime.
AT&T Bell Laboratories recognized the need to satisfy these objectives and used
the term DFX to designate designing for all desired factors.2 DFX was described as a
design procedure in which the objective broadly covers cost-effective “downstream”
operations: distribution, installation, service, and customer use. Reliability, safety,
conformance to environmental regulations, and liability prevention are also objectives.
These are in addition to low manufacturing costs. DFX is “the process where the full
life-cycle needs of the product are addressed during the product’s design.” AT&T
made note of the value of incorporating DFX knowledge into CAE/CAD (computeraided
engineering/computer aided design). Education was stated to be essential.3
THE ATTRIBUTES OF A GOOD DESIGN
The following design objectives have been recommended as being most important.
Function and Performance
These are still vital. The product must perform the task for which it is designed.

Safety
Those involved in the manufacture, sale, and use of the product and other persons
must be protected from physical injury and illness. A sound design from the safety
standpoint is one whose manufacturing process does not involve hazards to workers; it
is one whose operation poses the minimum risks to the user and those in the vicinity;
it is one which, when the product is discarded after its useful life, does not entail hazardous
waste.
Long-Term Quality
That is, quality, reliability, and durability (the customer tends to group these objectives
together; the designer should also). Will the product continue to provide its
desired function over a period of time? Will it retain its appearance, its accuracy, its
ease of use, etc.? Quality and reliability result from care and attention at a number of
stages, but perhaps the most important stage is the design stage. Quality and reliability
cannot be built in if the basic design is not conducive to them.
Manufacturability
This includes testability, shipability, etc.—all the objectives of DFM.
Environmental Friendliness
This is closely related to safety but affects all living creatures and plant life. Will the
product, its manufacturing process, its use, and its disposal avoid the release of pollutants
and other environmental hazards? The manufacturing process should be one that
generates minimal pollution. The product itself should be nonpolluting and, as noted
above, nonhazardous in its operation and disposal. Even if nonhazardous, are its components
configured so that they can be recycled easily? Design for the environment
(DFE) has been used as a term to describe this approach. Design for disassembly is the
name given to the system of product design that emphasizes recyclability of components.
Primarily, this involves designs that ensure that recyclable components can be
separated easily from the rest of the product.
Serviceability (Maintainability and Repairability)
This involves the ease with which the product can be returned to use after some failure
has occurred, or the ease with which it can be attended to to avoid future failures. This
objective is closely related to reliability. Easy serviceability may compensate for what
otherwise would be a reliability problem.

User Friendliness, or Ergonomics
This involves how well the product fits its human users, how easy it is to use. (Human
factors engineering was a previously common term for the discipline that this
involves.) Is the product easy for the user to install and operate? Are all functions and
controls clear? User unfriendliness can lead to safety and reliability problems as well
as make the product less functional.
Appearance (or Aesthetics)
This is the attractiveness of the product, which may be a very important factor in its
salability, particularly with many consumer products.
Features
The accessories, attachments, and peripheral functions, like the stereo, air-conditioning,
and cruise control in an automobile, may be more important to the buyer than its
basic function, i.e., in the case of an automobile, transportation.
Short Time-to-Market
This is how suitable the design is for short lead-time production. This normally means
whether the design is one that requires unique long lead-time tooling for some of its
components. Short time-to-market has important implications in the current era where
product designs change rapidly and where commercial success often hinges on being
the first supplier to market a product with particular features. The company that puts
an innovation on the market first often reaps ongoing benefits in the form of increased
market share for its product.
Other objectives such as installability, testability, shipability, upgradeability, easy
customizing, etc., also may be important in many cases.

REFERENCES
1. James G. Bralla, Design for Excellence, DFX, McGraw-Hill, New York, 1996.
2. David A. Gatenby, “Design for `X’ (DFX): Key to Efficient, Profitable Product Realization,”
in J. A. Edosomwan and A. Ballakur (eds.), Productivity and Quality Improvement in
Electronics Assembly, McGraw-Hill, New York, 1989, Chap. 45.
3. R. A. Layendecker and B. Suing Kim, “From DFMA to DFX: An AT&T Example,” paper presented
at the 1993 DFM Conference at the National Design Engineering Conference, Chicago,
March 1993.