2016ARS_NA_Blue_S7_Rioux

Blue Room, Session 7
2016 ARS North America
Begins at 10:30 AM, Wednesday, June 22nd
Cost Reduction by Structured Reliability Engineering
Creating Raving Fans!
Michael Rioux
Stratasys, Inc.
Reliability Matters

PRESENTATION SLIDES
The following presentation was delivered at the:
International Applied Reliability Symposium, North America
June 21 - 23, 2016: San Diego, California
http://www.arsymposium.org/2016/
The International Applied Reliability Symposium (ARS) is intended to be a forum for reliability and maintainability
practitioners within industry and government to discuss their success stories and lessons learned regarding
the application of reliability techniques to meet real world challenges. Each year, the ARS issues an open
"Call for Presentations" at http://www.arsymposium.org/present.htm and the presentations
delivered at the Symposium are selected on the basis of the presentation proposals received.
Although the ARS may edit the presentation materials as needed to make them ready to print, the content of the
presentation is solely the responsibility of the author. Publication of these presentation materials in the
ARS Proceedings does not imply that the information and methods described in the presentation have been
verified or endorsed by the ARS and/or its organizers.
The publication of these materials in the ARS presentation format is
Copyright © 2016 by the ARS, All Rights Reserved.

Michael Rioux, Stratasys Slide Number: 2Session 7
AppliedReliabilitySymposium,NorthAmerica2016
Blue Room
Agenda
 Introduction 5 min
 Case Study: Reliable cost reduction strategy 10 min
 Structured Reliability Engineering 30 min
 Gather the Data
 Model & Predict
 Develop the D.R.T.P.
 Execute the Plan
 Publish Results
 Summary 5 min
 Questions 10 min

Blue Room
Acronyms
 D.R.T.P. : Demonstrated Reliability Test Plan
 VE : Value Engineering
 NPI : New Product Introduction
 FDM : Fused Deposition Modeling
 MIC/s : Micro Inch Cubed/second. Volumetric flow rate
 UUT : Unit Under Test
 CRU : Customer Replacement Unit
 CAR : Corrective Action Request
 RCA : Root Cause Analysis
 OEM : Original Equipment Manufacturer
 TTT : Total Test Time

Blue Room
Introduction
 Michael Rioux: Sr. Systems Reliability Engineer
 Defining the process required to meet reliability goals
 Stratasys Inc.: 3D Printing Solution Company
3D printing is a way to create physical objects directly from digital files.
 Technologies
 FDM creates parts layer-by-layer with engineering-grade
thermoplastics
 PolyJet is a process that jets and cures thin layers of liquid
photopolymers with UV energy

Blue Room
Case Study: Reliability and Cost Reduction
 Once a new product has been released to
production, the next step is to launch a cost
reduction initiative (VE).
 VE techniques
 Redesign
 Decrease Existing Component Cost
 Component Substitution
 Re-source/Out-Source
 De-Feature
 We will explore a reliability–focused plan for
reducing cost by component substitution.

Blue Room
Case Study: Reducing cost w/o sacrificing reliability
 Common industry part types, technology and
competition do not guarantee rise to equally reliable
parts.
 If component substitution is left in the hands of the
procurement organization, the end result could be the
purchasing of inexpensive parts w/o sufficient
consideration to the impact on product reliability.
 Using a systematic structured reliability engineering
approach to achieve cost reduction not only yields
cost improvements, but creates customer loyalty.

Blue Room
Case Study: Cost Reduction by Reliability Engineering
Challenge:
Purchasing has identified a lower cost
replacement motor w/encoder for the NPI FDM
extruder.
Objective:
Evaluate the proposed replacement component’s ability
to meet the allocated reliability, and performance
requirements as specified in the “Product Market Design
Requirements” document.

Blue Room
Structured Reliability Engineering
Step 1:
 Understand the use case
 Review the Market Requirements Document
o MTTF, Allocation, Utilization, BX% Life…
 Review the original DFMEA
 Check the 3-F’s (Form, Fit, and Function)
 Review Component datasheet and Application notes
 Audit OEM Quality
[ 6 tasks ]

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Understand the use case
[ 1 : 6 ]

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Review the Market Requirements Document
 The FDM extruder shall be a consumable item/CRU which is
easily replaced by the customer after 1100 build hours. The
extruder shall not be attached to either the model or support
material consumable.
 The FDM extruder motor must not exceed a B15%(CL 80%) Life
requirement, ideal would a B10%, allowing for future reliability
growth in the head assembly.
 FDM extruder shall operate at 7VDC (+/-2v), 50°C (+/-3°C), and
provide 8lbs push force at 1600MICS with an acceleration of
100,000 MICS/s.
[ 2 : 6 ]

Blue Room
Review the original DFMEA
Any Failure Mode(s) that would over stress the replacement motor life or
performance?
• No-load speed
• No-load current
• Stall torque
• Stall current
[ 3 : 6 ]

Blue Room
Check the 3-F’s (Form, Fit, and Function)
 Form: shape, size, dimensions, mass, and weight
 Fit: ability of part to physically interface with, connect to, or
become an integral part of another part
 Function: ability to perform as required
In this case study the replacement motor
was an exact copy, drop-in replacement.
Any change in the 3-F’s that constitutes a
modification of the extruder assembly would
have required a battery of qualification tests
for various components and sub-assemblies
[ 4 : 6 ]

Blue Room
Review component Data sheet(s) and Application notes
We are interested in comparing the differences between the component’s
parameters (Present vs. Suggested):
Data sheet
• Voltage range
• Current response
• Power consumption
• Operating temperature limits
• Performance chart
• Reliability data
Application notes
• Factors affecting motor performance
• Application use case
• Testing
[ 5 : 6 ]

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Audit OEM Quality
Review the following:
1. Compatible w/design application & manufacturing process?
2. Continuous Reliability improvement program implemented?
3. Feedback & corrective action program in place?
4. Device families prequalified periodically?
5. Qualified and approved manufacturer?
6. Early Life Reliability Control?
7. Lot-to-Lot controls in place?
How will these answers impact
the motor’s predicted
reliability?
[ 6 : 6 ]

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This step is a preliminary evaluation to determine if suggested substitution component,
the motor, is a plausible candidate. Only then is it worth investing time and resources to
perform reliability testing.
 Fishbone Diagram: identify possible causes for any effect on the motor.
 Predict MTBF: utilized ReliaSoft Lambda Predict.
 Calculate BX%: based on prediction.
 Conclusion: does the results support moving forward?
[ 4 tasks ]Step 2:

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Step 2:
FISHBONE DIAGRAM
[ 1 : 4 ]

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Step 2:
MTBF
Adjustment factors were best
concluded by working with the
OEM of the motor in question,
researching historical data,
and/or provided by the results
of an internal study.
[ 2 : 4 ]

Blue Room
Step 2:
Does the predicted MTBF support the BX% requirement?
Case 2: future Tr requirement for extended replacement period.
Tr = 1500hrs
m = 9.978E+03 (predicted MTBF)
‫؞‬R = /
= 0.8604
‫؞‬BX% = 100% – 86.04% ≈ 14%
‫؞‬LIFE = B14%
Case 1: specification requirement for Tr .
Tr = 1100hrs (rounded up from 1095)
m = 9.978E+03 (predicted MTBF)
‫؞‬R = /
= 0.8956
‫؞‬BX% = 100% – 89.56% ≈ 10%
‫؞‬LIFE = B10%
[ 3 : 4 ]

Blue Room
Step 2:
CONCLUSION
The preliminary model, and predicted BX%, does satisfy the desired reliability
requirements. However, the model must be verified by performing a demonstrated
reliability test. Nonetheless, the preliminary results do indicate the motor is plausibly a
candidate to support the cost reduction initiative, and therefore worth the time and
resources for further assessment.
Moreover, this study has identified plausible components of high risk: the motor
brushes and encoder disk. Said components shall be closely monitored during the
demonstrated reliability test to determine the overall impact on the motor’s ability to
meet the life/performance requirement.
In closing, may it be clearly understood that during the demonstrated reliability test
execution, both electrical and mechanical parameters are tested to their intended use
requirements. This assures all concerned parties that the UUT meets the intended
use case reliability specifications; however, it will not provide information outside the
use case.
[ 4 : 4 ]

Blue Room
Step 3:
 Baseline component: functional test, quality review.
 Dissect motor to evaluate/measure internal components
 Calculate sample size & total time to test: Weibull++ ReliaSoft Test design.
 Design test strategy: Test methodology, configuration, thermal profile,
electrical/mechanical parameters, motor load, test profile, data collection.
 Define fail criteria: work with design team.
 Define test resources: equipment, materials, and time line.
[ 5 tasks ]

Blue Room
Step 3:
 Baseline component: Prior to test commencement all motors shall be functionally tested to
baseline performance characteristics. Furthermore, a motor shall be dissected to evaluate initial
quality, and measure the DC commutating brushes and bushings at run time equal to zero.
Bench top set-up Encoder output signal Waveform Signature
Equipment List
UUT: ACME motor w/encoder (PN: AB20100)
DAQ: Tektronix :: MSO4104B-L Mixed Signal O-scope
PS: Topward model 6303D (property ID: 0223)
Load: ULTEM
Brushes
Brass Bushing
[ 1 : 5 ]

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Step 3:
Brushes
As the motor will be replaced before entering wearout, the distribution was governed by
a 1P Exponential distribution.
[ 2 : 5 ]

Blue Room
Step 3:
Brushes
Test Strategy Designed to evaluate the proposed motor’s ability to meet the
reliability as predicted in the preliminary motor evaluation.
• Electrically terminated to 7VDC source
• Dressed with thermocouples
• Chamber set to 60°C (design margin) w/ 55%RH
• Motor shafts shall be fixed with a load inertial disk
• Encoder output signal shall be captured
• Input V/I, and case temperature captured
• Motor enclosed in an enclosure as in use case
• Motor exercised in repetitive CW/CCW direction
• 20 UUTs executing
• 5 extra UUTs for random interval internal inspections
• Internal inspection: brush/bushing wear, contamination,
insulation breakdown
TTT min = 1530hrs/UUT (CL = 80% w/1failure)
Test Configuration
[ 3 : 5 ]

Blue Room
Step 3:
Brushes
Fail Criteria: Critical to work closely with the design engineers to understand
performance limitations. If available, review customer surveys.
• Motor seizes
• Wire insulation breakdown
• Motor temperature exceeds 100°C (impacts motor performance)
• Missing output encoder count signals during TTT
• Encoder noise to signal ratio greater than 5% during TTT
• Brush wear greater than 80% after 1500 hours of execution (worst case in population)
• Encoder output signal degrades by more than 10% over TTT
• Bushing wear greater than 1% after 1500 hours of execution (worst case in population)
• Motor fails to maintain commanded acceleration performance signal (drift > 1%)
[ 4 : 5 ]

Blue Room
Step 3:
Brushes
Schedule & Resources
UUT: motor (25pcs)
Enclosures: (25pcs)
Load Disks: (25pcs)
TC DAQ: Agilent 34970A
TC: Type K :: (50pcs)
DC Sources: BK Precision 1900
Test Chamber: Despatch
Encoder DAQ: NI
[ 5 : 5 ]
Test extended to 3416hrs

Blue Room
Step 4:
Brushes
 Set-up test
 Perform RCA on any undesirable event
 Update Weibull++ folio
 Perform Interval audits: Brush and bushing wear, contamination buildup
 Review captured data daily: Motor case temp, velocity, acceleration, etc.
[ 5 tasks ]

Blue Room
Step 4:
Brushes
Think safety, durability, and serviceability.
Your data is only as reliable as your test set-up.
[ 1 : 5 ]

Blue Room
Brushes
Time
ACCELERATION (count/sec^2) Current (Amps) Temperature (°C) Motor Voltage Enclosure Temperature (°C)
Motor 9 Motor 10 Motor 11 Motor 12 Motor 9 Motor 10 Motor 11 Motor 12 Motor 9 Motor 10 Motor 11 Motor 12 Motor 9 Motor 10 Motor 11 Motor 12 Motor 9 Motor 10 Motor 11 Motor 12
10:44:42 AM 3250000 3500000 3250000 3500000 0.13 0.13 0.15 0.12 45.16 45.67 45.81 45.57 7.00 7.03 7.03 7.00 44.43 43.04 43.71 43.07
10:52:24 AM 3500000 3250000 3500000 3500000 0.14 0.13 0.15 0.12 47.04 47.65 45.81 47.51 7.00 7.03 7.03 7.00 44.60 43.80 44.08 43.51
10:53:54 AM 3250000 3500000 3000000 3750000 0.14 0.14 0.15 0.12 50.85 51.61 51.71 51.21 7.00 7.03 7.03 6.99 44.68 43.34 43.87 43.21
10:55:25 AM 3000000 3500000 3000000 3250000 0.18 0.18 0.19 0.12 54.92 55.76 55.29 55.19 7.00 7.04 7.04 6.99 44.78 43.09 43.87 43.24
10:56:55 AM 3250000 3250000 3250000 3500000 0.14 0.14 0.15 0.13 58.74 59.64 59.74 58.88 7.00 7.04 7.04 7.00 45.48 44.56 44.46 44.20
10:58:25 AM 3250000 3250000 2750000 3250000 0.14 0.15 0.15 0.13 62.29 63.21 63.31 62.28 7.00 7.04 7.04 7.00 45.77 44.25 44.51 44.27
10:59:56 AM 3250000 2750000 3000000 3000000 0.15 0.15 0.15 0.13 65.49 66.42 65.51 65.41 7.00 7.04 7.04 6.99 44.97 43.47 44.69 44.16
11:01:26 AM 3000000 3000000 2750000 3250000 0.15 0.15 0.15 0.13 68.46 69.36 69.46 68.27 6.87 7.04 7.04 6.85 45.71 44.41 45.19 44.66
11:02:56 AM 3250000 3000000 2750000 3250000 0.16 0.15 0.16 0.14 71.10 72.03 70.96 70.86 6.99 7.04 7.04 6.99 45.52 44.38 45.39 45.10
11:04:27 AM 2750000 3250000 2750000 3250000 0.15 0.15 0.16 0.14 73.56 74.44 74.54 73.23 6.97 7.03 7.04 6.96 45.90 45.59 45.77 45.55
11:05:58 AM 3250000 3250000 2750000 3000000 0.16 0.16 0.16 0.14 75.80 76.63 75.53 75.43 6.97 7.04 7.04 6.97 46.55 46.50 46.24 46.27
11:07:28 AM 3000000 3000000 3000000 3250000 0.16 0.16 0.16 0.15 77.85 78.67 78.77 77.49 7.00 7.04 7.04 7.00 47.10 46.22 46.32 46.80
11:08:59 AM 3000000 2750000 2750000 2750000 0.16 0.16 0.16 0.15 79.74 80.52 79.46 79.36 7.00 7.04 7.04 7.00 47.62 46.66 47.16 46.69
11:10:29 AM 3250000 3000000 2500000 2750000 0.17 0.16 0.17 0.15 81.53 82.30 82.40 81.14 6.92 7.04 7.04 6.93 47.87 47.48 47.39 47.83
11:12:00 AM 3000000 2750000 2500000 2750000 0.17 0.16 0.17 0.15 83.11 83.85 83.95 82.71 6.99 7.04 7.04 6.99 48.10 47.27 47.85 48.18
11:13:30 AM 2750000 3000000 2750000 2750000 0.17 0.17 0.17 0.16 84.65 85.33 85.43 84.20 6.99 7.04 7.04 6.99 48.65 47.25 47.67 47.78
11:15:01 AM 2750000 2750000 3000000 3250000 0.18 0.17 0.17 0.16 86.02 86.66 86.76 85.56 7.00 7.04 7.04 6.99 48.75 47.94 48.25 48.31
11:16:31 AM 2500000 2750000 2500000 2750000 0.18 0.17 0.17 0.16 87.29 87.88 87.98 86.81 7.00 7.04 7.04 6.99 49.63 48.45 48.55 48.58
11:18:02 AM 2500000 2750000 2500000 2500000 0.18 0.17 0.17 0.16 88.51 88.99 89.09 87.99 6.99 7.04 7.04 6.99 49.63 48.03 49.08 49.48
11:19:33 AM 2750000 2750000 2750000 2750000 0.18 0.18 0.17 0.16 89.62 90.06 90.16 89.09 7.00 7.04 7.04 6.99 49.85 49.00 48.88 49.56
11:21:04 AM 2750000 3000000 2750000 2750000 0.18 0.17 0.17 0.16 90.57 90.95 91.05 90.05 6.98 7.04 7.04 6.98 50.05 49.01 49.02 49.53
11:22:34 AM 2750000 2750000 2500000 2750000 0.18 0.18 0.17 0.17 91.45 91.85 91.95 90.98 6.98 7.04 7.05 6.98 50.30 49.62 49.63 49.82
11:24:05 AM 2750000 3000000 2750000 3000000 0.18 0.18 0.17 0.17 92.32 92.66 92.76 91.87 6.99 7.04 7.05 6.99 51.09 49.65 49.90 50.09
Step 4:
Daily Performance Data.
[ 2 : 5 ]

Blue Room
Step 4:
Discovery :: Perform Random Interval Audits ::1 motor/audit
Contamination
(Brush dust build up)
Bushing wear after 550hrs
Encoder disk discoloration
Motor brush/bushing assembly
Brushes
Bushing
Motor brush wear after 550hrs
[ 3 : 5 ]

Blue Room
Step 4:
Brushes
Folio :: Extruder Motor :: Total sample space = 25
In this study the folio was built on ReliaSoft’s Weibull++. The LDA was modeled with an
exponential function since the design of the complete sub-assembly would be replaced
prior to entering wearout.
[ 4 : 5 ]

Blue Room
Step 4:
Brushes
RCA :: Extruder Motor :: 5 Whys & the Fishbone
In this study three undesirable events occurred. Utilizing the 5 Whys & the Fishbone
diagram, along with working with the OEM to understand how all the undesirable events
occurred. The following root cause was concluded.
Dorado
Motor
Failure
Winding
Bushing
Motor Failure Components
VOLTAGE SURGES
OVERHEAT
OPEN/SHORTED
CONTAMINATION
Motor Insulation
Stator
Encoder
Rotor
OVERHEATING
OVERLOADING
VIBRATION
AGING
VIBRATION
CORROSION
Enclosure
CORROSION
INCORRECT FITTING
MANUFACTURING ASSEMBLY
VIBRATION
ASSEMBLY
CONTAMINATION
MIS-WIRED
LOOSE MAGNET
CORROSION
IMBALANCE
Shaft
IMPROPER ASSEMBLY
MISALIGNMENT
OVERLOADING
CONTAMINATION
THERMAL STRESS
MOISTURE
Connector
VIBRATION
MISALIGNMENT
HIGH TEMPERATURE
CONTAMINATION
DISK FAILURE
OV/OC
CABLE FAULT
HEAT
OVERHEAT
CONTAMINATION
HIGH VIBRATION
HIGH VIBRATION
PHYSICAL DAMAGE
PHYSICAL DAMAGE
VIBRATION
CORROSION
OV/OC
brushes
VIBRATION
CORROSION
PHYSICAL DAMAGE
HIGH TEMP
MOTOR SPEED
DIRECTION
CONTAMINATION
“5 Whys”
1. Why did the motor stop?
Not enough torque
2. Why not enough torque?
Too much friction
3. Why too much friction?
Shaft misalignment (2), bushing to shaft seized (1)
4. Why shaft misaligned, and seized?
Shaft bent(2), contamination(1)
5. Why bent shaft, and contamination?
Improper assembly in all cases,
Load disk press force too high(2)
Overfill of epoxy(1)
[ 5 : 5 ]

Blue Room
Step 5:
Index
 Demonstrated MTTF & BX%
 Functional Test Results
 Internal Component Review
 RCA /CAR
 Final Conclusion
[ 5 tasks ]

Blue Room
Step 5:
Brushes
LDA :: MTTF:: BX%
After executing the test for 3416hrs, all surviving UUTs were suspended, then the
final results were analyzed to determine the MTTF and BX%.
F= 3/S= 22
Demonstrated MTTF exceeds the predicted!
B15% >> 1100hrs
BX% (1100hrs) = 4.9%
[ 1 : 5 ]

Blue Room
Step 5:
Brushes
Functional Test Results
It can be seen below that the motor's velocity and acceleration performed reliably
to the commanded test control signal. We can also observe that output signal had
been stable and repeatable throughout the total test period.
Measurements below are from the seam stress part test, which is our best measurement
of the motor’s ability to accurately/reliably control the extrusion volumetric.
[ 2 : 5 ]

Blue Room
Step 5:
Brushes
Internal component review :: BUSHING REVIEW
Prior to executing test, a sacrificial motor was disassembled to learn of the bushing
quality and initial dimensions. These dimensions were utilized to understand the wear
out. The measurements weren’t used to perform a degradation analysis. But merely to
observe if any unexpected wear surfaced that may jeopardize the motor’s predicted
reliability. Furthermore, this exercise had assisted in understanding plausible failure
modes. Note below for a before/after picture of the bushing.
Wearout < 1%
[ 3a : 5 ]

Blue Room
Step 5:
Brushes
Internal component review :: BRUSH REVIEW
If we assume all the brushes at t = 0 are of the same length (+/-.01%) ,the worst case brush
wear rate in our sample space was 6.0E-5in/hour (+/-.01%). This would lead to a total wear of
0.09” after 1500 hours of run time.
‫؞‬(0.139” t = 0) – (0.09” t = 1500) = 0.049”wear ‫؞‬ 35.3% wear out at 1500 hours < 80%
Motor 21 3416.000 hrs
[ 3b : 5 ]

Blue Room
Step 5:
Brushes
RCA/CAR result
• Total of 3 failures occurred during the total test period.
• All assembly induced failures.
 Overstressing the motor shaft
 Contamination
Corrective Action Request:
• In production the use of a gear press tool
shall be utilized, and the edges of the shafts
and the gear holes will be chambered
helping to distribute the force evenly around
the circumference.
• Work instructions, and training on how to
properly use gear press and applying
Loctite after the gear is pressed onto the
shaft.
[ 4 : 5 ]

Blue Room
Step 5:
Brushes
Final Conclusion
All conducted tests have demonstrated that the suggested motor exceeds the allocated
extruder reliability requirements. Therefore said motor is an approved direct drop-in
replacement to support the VE cost reduction by component substitution initiative.
However, this case study shall not be considered to provide any reliability information
outside the extruder use case.
[ 5 : 5 ]

Blue Room
Summary
Brushes
• Don’t assume that common industry part types and market competition gives
rise to parts of equal reliability.
• Executing the VE initiative: component substitution; without sufficient
consideration to the impact on product reliability, could lead to loss of profits
and customer loyalty.
• To sustain customer loyalty a Structured Reliability Engineering Evaluation
Process must be integrated into the Value Engineering Strategy.
• Question everything!

Blue Room
Michael Rioux, Sr. Systems Reliability Engineer
michael.rioux@stratasys.com
Michael Rioux is a Senior Systems Reliability Engineer at Stratasys, Inc.
supporting design and test engineering. In this role he is responsible for defining
the process required to meet reliability goals for New Product Development.
Michael received his Baccalaureate of Science from Northeastern University,
Boston, Massachusetts. He began his engineering career at MIT designing
electrical/electronic hardware for analyzing Plasma Fusion. For 25+ years he
continued to design hardware for various projects supported by the DoD, DoE, as
well as various commercial Industries.
Over the last five years he has transitioned into the role of Reliability Engineering.
Michael is not only providing product reliability analysis, with his experience in
design engineering, he is reviewing system designs to propose design
modifications that have a direct impact on improving product reliability.

Blue Room
Questions
Thank you for your attention.
Do you have any questions?

2016ARS_NA_Blue_S7_Rioux

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