describe [robust engineering] as just plain good engineering
and not all that joltingly new. Others view it as merely another
fad. Using robust methods saved time and money in developing
Saturn's manual and automatic transmissions, and also produced
about 30 new patents."
- Robert C. Downs,
Chief Engineer-transmissions at GM's Saturn subsidiary
early, methodical application of Quality Engineering [robust
design]`best practices' within a disciplined product development
process will yield improved reliability along with many other
economic and quality related benefits."
- Skip Creveling,
Eastman Kodak Company
auto industry isn't alone in using robust engineering procedures.
The philosophy has its converts in diverse industries such as
aerospace, appliance manufacturing, and electronics. Proponents
have developed mathematical formulas for measuring the "robustness"
of individual designs and report cases of dramatic improvements
when robust engineering guidelines have been applied to specific
- (WARD'S Auto World - March 1994)
(Accelerating Non-Linear Finite Elements Analysis Using Taguchi Techniques)
was to improve the speed of computer solutions for Finite Element Analysis
through proper settings of parameters in the computer program. After
using Taguchi Methods to determine the optimum settings, a fivefold
reduction of run-time was achieved.
Arbor Assembly Corporation
(Parameter Design for a Heat Staking Process)
was conducted to find a combination of levels for the controllable factors
that would produce good adhesion during the assembly of rubber gaskets
to the body portion of automobile hood hinges, in the presence of a
specified production. Good adhesions are now achieved more consistently,
and an annual cost savings of $18,000 was realized in the reduction
of scrap and rework, and an overall total of more than $50,000 in annual
(Computer Response-Time Optimization Using Orthogonal Array Experiments)
was to reduce a computer system's response time under a specified range
of load and environmental conditions. This was achieved by simultaneously
studying a large number of system parameters, as opposed to studying
one parameter at a time. The resulting optimum system configuration
gave a 60% reduction in mean response time.
(Oxygen Sensor Variability Reduction)
of measured value from an oxygen sensor used for open heart surgery
was reduced by 70%. In addition (using a double-signal approach), a
robust function was developed to compensate for changes in blood temperature.
(Sheet-Molded Compound Process Improvement)
was to identify controllable and significant material and process variables
that could minimize the effect of Sheet-Molded Compound (SMC) formulation.
First-time-through capability of the finished product improved from
77% to 96%. Supplier scrap was reduced from 16% to 1.7%. Reduced inspection
cost repair and costs due to optimization are estimated at $900,000
(Pinch Roller System of Optimization: A Comparison Between Traditional
DOE and Taguchi Methods)
required to perform the data analysis for both the Taguchi and traditional
analysis is comparable, and is insignificant compared to the time required
for data gathering. For this study, the time required to gather data
was approximately one hour per experiment. Twenty-seven experiments
were required to generate the Taguchi data, and 60 experiments were
required to perform the traditional analysis. The time required for
the Taguchi experiments was only 45% of the time required for traditional
(Factors Affecting Solvent-Bonded Connector Durability: Optimization
of the Strength of an Emission Control Harness Assembly)
investigated the improvement of automotive emission control harnesses.
This product must conduct vacuum signals to various devices that alter
the combustion engine's performance to minimize emissions. A low but
noticeable number of solvent-bonded harnesses were found separated in
finished assemblies. Application of Taguchi's methods resulted in a
reduction in parts failure from 17% to 1.1%. As a result, an inspection
cost savings of $200 per 1,000 pieces was realized on monthly production
of 500,000. ($1.2 million annually).
(Fuel Pump Flow)
range in fuel pump flow was reduced by 65%. Development of a new fuel
pump with severe requirements was completed eight months prior to plan
as a result of this study.
Division, SPX Corporation
(Cold-Start Noise Reduction for Hydraulic Roller Tappets)
was to reduce cold-start noise in a 5.2 litre V-8 gasoline engine. As
a result of this study, tappet noise was reduced by 75%, and an estimated
annual savings of $4,900,000 was achieved.
(High Voltage, High Temperature Wire Strip Force Optimization)
study examined strip-force problems associated with one type of high-voltage,
high-temperature wire used in the electronic OEM marketplace. Variability
of strip-force was the primary cause of rejection. The objective was
to minimize strip-force variation around a target value. As a result
of bringing the process under control, an annual savings in material
and production cost of $100,000 was achieved.
(Optimization of the Strength of Diesel Injection)
was to reduce the rework rate of a diesel injector on the assembly and
test operation. After the first stage of Taguchi Methods implementation,
a 17% reduction in rework was realized and another 4% after a second
stage of implementation. This equates to an annual cost savings of 14,880
American Reiss, Kenkor Division
(Optimization of a Hot-Stamping Process)
Methods, specifically Parameter Design, was used to assist design engineers
in developing a product that both meets their needs and is manufacturable.
In less than one month, a hot-stamping process was both established
and optimized. The results not only yielded 100% conformance, but enabled
the design engineers to develop realistic product requirements in less
than half the normal time.
(Brake Pad Study)
characteristics, Nissan improved the efficiency of the energy transformation
to the brake pad. Overall weight of the brake system was reduced and
squeal rate was reduced to 4% of the original condition. Nissan Technical
Center conducts 70 projects annually, all using dynamic characteristics.
(Space Shuttle Main Engine Nozzle Brazing Improvement)
of the furnace brazing process resulted in a reduction in variation
of 82%. Cycle time was reduced to 1/3 of the original process.
(Bean Sprout growing process)
broke the traditional bean sprout growing paradigm "Beans that grow
fast do not have a good shelf life, and beans that grow slowly do not
become large enough." The time to grow a bean sprout was reduced from
7 days to 4 days without affecting taste or shelf life, a 40% improvement
(Copy machine paper arrival time)
the variability in arrival time and paper orientation by 66%. Xerox
is probably the most advanced user of Taguchi Methods in the U.S. They
started implementation of Robust Design in 1982, and today the Robust
Design approach is fully integrated into their product development process.