Monthly Archives: April 2012

MD&M East – May 22-24, 2012, Philadelphia, PA

Ops A La Carte’s Mike Silverman will be giving a three hour class on "Medical Reliability Testing – Identifying Testing Requirements Early."

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Robust Design & Reliability

      I delivered a webinar recently  to  describe   the  differences and similarities between robust design (RD)  activities and reliability engineering (RE)  activities in hardware product development .  A survey we took from   several hundred attendees indicated a diversity of opinions. About half the participants indicated they did not differentiate at all between the two methodologies.  Approximately 20 % indicated they did differentiate between the two methodologies, and about 30% indicated that they did not know.

I was quite surprised at the result, especially since participants came  from  working quality engineers, reliability engineers, engineering directors, system engineers, etc.  Somewhere along the way,  the  differences and similarities between the two seem to have become muddled.  Below I have    collected just twelve of the many ways in which the activities are different:


RD 1  Focus on design  transfer functions, and  ideal function development

RE 1  Focus on design dysfunction, failure modes, failure times, mechanisms of failure


RD 2   Engineering focus, empirical  models, generic models , statistics.

RE 2    Mechanistic understanding, physical models,  science oriented  approach.


RD3  Optimization of input-output functions with verification testing requirement

RE3  Characterization of natural phenomena with root cause analysis and  countermeasure decisions


RD4  Orthogonal array testing, design of experiments planning

RE4   Life tests , accelerated life tests, highly accelerated tests, accelerated degradation tests, survival  methods


RD5   Multitude of control, noise, and signal factor  combinations for reducing sensitivity to noise and amplifying sensitivity to signal

RE5   Single factor testing,  some multifactor testing ,   fixed design with  noise factors,  acceleration factors


RD6   Actively change design parameters to improve insensitivity to noise factors, and sensitivity to signal factors

RE6   Design-Build-Test-Fix cycles for reliability growth


RD7   Failure inspection only with verification testing of improved functions

RE7   Design out failure mechanisms, reduce variation in product strength. Reduce the effect of usage/environment


RD8  Synergy with axiomatic design methodology including ideal design, and simpler design

RE8   Simplify design complexity for reliability improvement.  Reuse reliable hardware .

RD9   Hierarchy of quantitative design   limits including functional limits, spec limits, control limits, adjustment limits

RE9   Identify & Increase design margins, HALT & HASS testing to flesh out design weaknesses.   Temperature & vibration stressors predominate


RD10   Measurement system and response selection paramount

RE10   Time-to-failure quantitative measurements supported by analytic   methods


RD11  Ideal function development for energy relate measures

RE11  Fitting distributions to stochastic failure time data.  Time compression by stress application



RD12  Compound noise factors largest stress.  Reduce variability to noise factors by interaction between noise and control factors, signal and noise factor.

RE12  HALT & HASS highly accelerated  testing to reveal design vulnerabilities and expand margins.  Root cause exploration and mitigation


There are many other differences of course, but this list should start the conversation .  I  would invite bloggers to submit their own opinions  and  lists of differences (and similarities) .

Louis LaVallee

Sr. Reliability Consultant

Ops a la Carte



SMTA Conference on Soldering and Reliability – May 15-18, 2012, Toronto

Ops A La Carte’s Peter Arrowsmith will be giving a presentation at this conference on "Improving Product Reliability Using Accelerated Stress Testing".

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IPC Conference on Test & Inspection – May 15-17, 2012, Costa Mesa, CA

Ops A La Carte will be giving a presentation at this conference on "New Techniques for More Effective ESS".

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May 7-11, 2012 in Santa Clara, California and via webinar

Design for Reliability (DfR): May 7-8
Design for 6 Sigma (DfSS): May 9
Design for Mechanical Reliability (DfMR): May 10
Design for Warranty (DfW): May 11 morning
Design for Software Reliability (DfS): May 11 afternoon

Design of Experiments (DOE): May 7-8
Best Accelerated Reliability Tests (BART): May 9-10
Root Cause Analysis (RCA): May 11

Each attendee will receive a copy of Mike’s book "How Reliability Is Your Product: 50 Ways to Improve Product Reliability"

Location: 990 Richard Ave, Suite 101, Santa Clara, CA 95050 and via webinar
Price: $1195 for each 2 day course, $695 for each 1 day course, $395 for each 1/2 day course.25% discount for seminars taken via web-conference
Group Rates: Every 5th registrant (or the 5th day for one registrant) is free

You can Find Out More Here.