Page 202 - Design for Six Sigma a Roadmap for Product Development

Design for Six Sigma Project Algorithm 175

are key, equal team members. However, the individuals involved in the
“design for X” (DFX, where X manufacturability, reliability, environ-
ment, assembly, testing, service, aesthetics, packaging/shipping, etc.)
merit special attention. X in DFX is made up of two parts: life-cycle
processes (x) and performance measure (ability), i.e., X x ability.
DFX is one of the most effective approaches to implement concurrent
engineering. For example, Design for Assembly (DFA) focuses on the
assembly business process as part of production. The most prominent
DFA algorithm is the Boothroyd-Dewhurst algorithm, which developed
out of research on automatic feeding and automatic insertion.
DFX techniques are part of detail design where poka-yoke (error-
proof) techniques can be applied when components are taking form
and producibility issues are simultaneously considered [see Huang
(1996)]. Poka-yoke is a technique for avoiding human error at work.
The Japanese manufacturing engineer Shigeo Shingo developed the
technique to achieve zero defects and came up with this term, which
means “mistake proofing.” A defect exists in either of two states; the
defect either has already occurred, calling for defect detection, or is
about to occur (i.e., is imminent), calling for defect prediction. Poka-
yoke has three basic functions to prevent or reduce defects: shutdown,
control, and warning. The technique starts by analyzing the process for
potential problems, identifying parts by the characteristics of dimen-
sion, shape, and weight, detecting process deviation from nominal pro-
cedures and norms.
In design for reliability (DFR), not testing for reliability, the DFSS
team needs to anticipate all that can go wrong and improve the relia-
bility of the design by simplifying and reducing the number of and type
of components (note the agreement with design axiom 2), standardiz-
ing the parts and material to reduce variability, considering design
parameters to counteract environmental effects, minimizing damage
from mishaps in shipping, service, and repair, employing robust
processes that are insensitive to variation, and eliminating design
vulnerabilities.
The design for maintainability (DFM) objective is to assure that the
design will perform satisfactorily throughout its intended life with a
minimum expenditure of budget and effort. DFM and DFR are related
because minimizing maintenance can be achieved by improving relia-
bility. An effective DFM minimizes (1) the downtime for maintenance,
(2) user and technician maintenance time, (3) personnel injury result-
ing from maintenance tasks, (4) cost resulting from maintainability
features, and (5) logistics requirements for replacement parts, backup
units, and personnel. Maintenance actions can be preventive, correc-
tive, or recycle and overhaul.
Design for environment (DFE) addresses environmental concerns in
all stages of the DFSS algorithm as well as postproduction transport,