Page 384 - Design for Six Sigma a Roadmap for Product Development

354 Chapter Ten

one of the first members of the DFX family is Design for Assembly
(DFA). The DFX family is one of the most effective approaches to
implement concurrent engineering. DFX focuses on vital business ele-
ments of concurrent engineering, maximizing the use of the limited
resources available to the DFSS team. In DFA, the focus is placed on
factors such as size, symmetry, weight, orientation, form features, and
other factors related to the product as well as handling, gripping, inser-
tion, and other factors related to the assembly process. In effect, DFA
focuses on the assembly business process as part of production by
studying these factors and their relationships to ease assembly.
The DFX family started with DFA but continues to increase in num-
ber as fostered by the need for better decision making upfront, in par-
ticular those related to manufacturing. Manufacturing and production
issues are often ignored or omitted in early design steps. This over-
sight can’t be generalized because of the early work of Matousek (1957),
Neibel and Baldwin (1957), Pech (1973), and several workshops orga-
nized by CIRP (College Internationale de Recherches pour la Production)
and WDK (Workshop Design-Konstrucktion). Other efforts started in the
1970s by a group of researchers in the United Kingdom and at University
of Massachusetts and resulted in two different commercial DFA tools:
that due to Boothroyd and Dewhurst (1983) and the Lucas DFA (Miles
1989). They employed worksheets, data, knowledge base, and system-
atic procedures to overcome limitations of design guidelines, differentiat-
ing themselves from the old practices. The DFA approach is considered
a revolution in design for assembly.
The Boothroyd-Dewhurst DFA moved out of research of automatic
feeding and insertion to broader industrial applications, including man-
ual assembly, in particular, locomotive engine. This success led to the
proliferation of a new array of DFX, expanding the family to Design for
Manufacturability, Design for Reliability, Design for Maintainability,
Design for Serviceability, Design for Inspectability, Design for
Environmentality, Design for Recyclability, and so on.
DFX tools collect and present factuals about both the design entity
and its production processes, analyze all relationships between them,
measure the CTQs of performance as depicted by the physical struc-
ture, generate alternatives by combining strengths and avoiding vul-
nerabilities, provide a redesign recommendation for improvement,
provide if-then scenarios, and do all that with many iterations.
The objective of this chapter is to introduce the vital few members
of the DFX family. It is up to the reader to seek more in-depth material
using Table 10.1.
The DFSS team should take advantage of, and strive to design into,
the existing capabilities of suppliers, internal plants, and assembly
lines. It is cost-effective, at least for the near term. The idea is to create