The Implementation of the
NUD Process
How it is used to develop reliable products such as the
Lennox S30 thermostat
26 March 2019 | Joe Powell
9000 Virginia Manor Rd Ste 290, Beltsville MD 20705 | 301-474-0607 | www.dfrsolutions.com
Agenda
01
Why and what is NUDS
02
NUDS and FMEA
03
The NUDS Process
04
Lennox S30 and NUDs
05
Summary
06
Questions
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Why
•
•
•
•
•
Tool that is part of our DFR process.
In use for over 10 years.
Identify risks.
Begin mitigation sooner, with higher confidence of product success.
NUDS
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What is NUDs
• New: an adjective referring to something recently made, discovered, or created.
• Unique: a state or condition wherein something is unlike anything else.
• Difficult: requiring much work or skill to do or make.
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What is NUDs
• New: Just as it implies, anything that is new.
− First time using a material, component or technology.
› Switch, motor or LCD display never used before.
› Plastic material change.
› Newly implemented process.
− First time use in the present design.
› Used in xyz product, now used in abc product but same use and environment profile.
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What is NUDs
• Unique:
− Different use of material or component, with different use or environmental profile.
› What was used as an evaporator motor in a furnace, now is used as condenser motor in an
outdoor unit.
• Different ambient temperature, humidity, vibration, dust.
›
Same refrigerant pressure switch used in walk-in coolers, now is used in commercial HVAC.
• Also different ambient temperature and humidity, as well as duty cycles and use profile.
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What is NUDs
• Difficult: requiring much work or skill to do or make.
− Challenging agency or government regulation requirement.
›
Fuel efficiency improvement 20% by 2020 for automobile.
›
Phase out of ozone-depleting refrigerants.
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NUDs and FMEA
• Supportive and helpful for FMEA and design process, not
• Why do we need an alternative?
• FMEA NEVER GETS COMPLETED SOON ENOUGH!!!
Why not?
−
−
−
−
−
People are too busy. Schedule driven.
FMEA is boring, design is more fun.
Difficult to get all members to attend.
Paperwork check box.
Design engineer not skilled in preparing FMEA.
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a replacement.
NUDs and FMEA
• FMEA Output:
− Systematic identification of potential failures modes, and cause mechanisms.
− Manage risks.
− Recommend alternative solutions.
• All important for identifying tests to insure that the product meets all targeted
performance criteria, but especially reliability objectives.
• NUDs can provide the same and sooner.
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NUDs and FMEA
Ideal development process with DFMEA
Concept
Specification
DFMEA
Design
Production
Preproduction
Design Verify
Prototype
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NUDs and FMEA
What really happens with design DFMEA
Concept
Specification
Production
Preproduction
DFMEA
Design Verify
DFMEA
Design
Prototype
THIS DOES NOT WORK FOR RELIABILITY ENGINEERS
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NUDs and FMEA
Ideal development process with DFMEA, PFMEA AND S&IFMEA
Concept
DFMEA
Specification
S&IFMEA
PreProduction
PFMEA
Design
Design Verify
Prototype
Production
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NUDs and FMEA
What really happens with PFMEA and S&IFMEA
Concept
Specification
DFMEA
Design
Design Verify
PreProduction
Prototype
Production
PFMEA
and S&IFMEA
THIS DOES NOT WORK FOR ANYONE
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HOW DOES NUDs IMPROVE THIS?
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NUDs and FMEA
NUDs for design
NUDs
Concept
Specification
DFMEA
Design
Production
Preproduction
Design Verify
Prototype
RELIABILITY ENGINEERS CAN BEGIN TEST PLAN ON
HIGH RISK, SPECIAL REQUIREMENT ELEMENTS
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NUDs and FMEA
NUDs for Process and Service and Installation
NUDs
Concept
Specification
S&IFMEA
PreProduction
DFMEA
PFMEA
Design
Design Verify
Prototype
Production
THIS WORKS FOR P AND S&I FMEAs
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Summary to this Point
• New concept, NUDs.
− New
− Unique
− Difficult
•
•
•
•
Gets to high risks issues of change quickly.
Helps reliability engineer develop risks mitigation sooner.
Not a FMEA replacement.
Efficient utilization of resources.
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NUDs Process
FMEA Diagram
Block Diagram
DFMEA Form
P-Diagram
Interface
Matrix
Failure Mode
Worksheet
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NUDs Process
• Utilizes a portion of DFMEA process.
Block Diagram: Describes system relationships.
P-Diagram: Describes external factors.
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NUDs Process
NUDs Diagram
Block Diagram
DFMEA Form
P-Diagram
Interface
Matrix
NUDs
Failure Mode
Worksheet
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NUDs Development Example
Block Diagram Step
Input 2
Input 1
Output 1
24V Rectifier/
Regulator circuit
Power Supply
3.3V regulator circuit
HW
Detect ckt 1
Input Detection
Detect ckt 2
Detect ckt 3
XYZ
Control
Relay Driver
Output Drive 1
K5
R49
R46
Regulator Drive
R44
CPU function
Pump Drive
FW
GV Drive
C4
D12
D13
LED
PCB
R48
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NUDs Development Example
P-Diagram Step
Signal
Factors
INPUTS
XYZ Control: Noise
Factors
System Factors
Input 1
Input 2
Output 1
New/Unique/Difficult
Yes
No
No
User Factors
Voltage Surges
Number of cycles
Wiring
New/Unique/Difficult
No
Yes
Yes
Environmental Factors
Temperature
Humidity
Vibration
New/Unique/Difficult
No
No
No
XYZ Control
Response/
Ideal
Function
OUTPUTS
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NUD Electronic Example
• Cell Phone
− Next years model, what has changed.
Table with
Headers
Identify and
Record NUDs
NUD
Display/touchscreen
Identify and
Record Risk
RISK
MITIGATION
Breaking of glass.
Perform standard drop test.
Scratch resistance.
Perform standard scratch
test.
Touch sensitivity.
Different button supplier
and increased count of
presses.
List Mitigation
Method
Meet lifetime button
presses.
Perform touch sensitivity test.
Perform standard button press
life test with increased number of
cycles.
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NUDs Development, NUD Worksheet Step
• Simple:
Identify the
associated
risk.
List the NUD
NUD
RISK
Pump efficiency > 20 %
List the test,
analysis, method
you will use to
mitigate that risk.
MITIGATION
Fuel economy
Redesign -valve size and
shape
Insufficient torque
Improve pump flow
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NUDs Development
• Two reasons to develop NUD list:
− Type 1: Existing product change, upgrade etc.
− Type 2: New product development.
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NUDs Development
Type 1: Existing Product Change
What has
changed?
What is
different about
use?
New Parts?
ABC Control
What worries
you?
Anything
different about
environment?
KEEP ASKING QUESTIONS!! INTERACTIVE DIALOGUE
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NUDs Development
Type 2: New Product
New
Processor?
What have we
never done
before?
Different p/s
design?
XYZ Control
What wakes
you up at night?
More cycles
over lifetime,
different relay?
KEEP ASKING QUESTIONS!! INTERACTIVE DIALOGUE
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Summary
• NUDs process is straight forward table.
• Uses block diagram and p-diagram of FMEA process to focus thinking.
• Interactive dialogue with designer is important.
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How was NUDS used for S30 Testing
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NUDs and S30
What is S30
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NUDs and S30
HD Display
Over 250 parts
Over 135 parts
Over 500 parts
Device
DFMEA Lines
No. of Man Hours
HD Display
290
110
Mag Mount
218
60
Smart Hub
274
73
782
243
Total
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NUDs and S30
Display NUD list
NUD
Risk
Breakage for use or dropping
Scratch resistance
Capacitive Touch
Display Touchscreen
Chemical Susceptibility
UV susceptibility
Backlight life
Viewing angle, brightness and contrast
Life
Battery
Electronics
Plastic Housing
Microphone and speaker
PC Board
New Firmware
Temperature Sensor Location
Proximiity Detector
Fire
ESD susceptibility of regulator failure allowing
battery to thermally runaway.
EMI and Environmental
Environmental susceptibility
Durability and mounting strength.
Mitigation
Packaging drop test
Drop test without packaging
Test to be developed.
Electronic qualification test, touch
sensitivity test
Chemical exposure with environmental
stresses.
UV testing
Analytics for backlighting life.
Display testing
Combination of analytics and testing
under adverse conditions.
Fire test
Electronic qualification test
Electronic qualification test
UV testing, thermal shock,
FEA, Plastic
Durability (household chemicals)
Durability test to be developed
Loudness of speaker
Sensitivity of microphone
Thermal/mechanical stresses
Unintended operation or not meeting
specification
Poor temperature control
False triggering
Test to be developed.
Test to be developed.
FEA, HALT, Thermal Shock.
Firmware test
Temperature test
Proximity test
9 NUDs
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NUDs and S30
Mag-Mount NUD list
NUD
Risk
Magnetic support for display
Loss of strength over time.
Magcon Connector
Communication Bus
2 screw wall mount with sheetrock
anchors
Humidity Sensor
Plastic Housing
METZ Connector
Life
PC Board
Power supply
Corrosion, connection reliability
Maintain spring tension
EMI
Holding strength to wall versus removal
strength of display
EMI
Accuracy
Environmental susceptibility
Durability and mounting strength.
Corrosion, connection reliability
Meet Lennox life requirements
Thermal/mechanical stresses
EMI
Handle range of input voltage
Mitigation
Analytics. Test to be
developed.
Corrosion test
Test to be developed.
Electronic qualification test
Analytics. Testing to be
developed.
Electronic qualification test
Humidity sensor test
UV testing, thermal shock,
FEA, Plastic
Corrosion/connector test
ALT
FEA, HALT, Thermal Shock.
Electronic qualification test
New processor
EMI/Environmental/Life
Electronic qualification test and
ALT
Communication protocol to HD Display
EMI/Environmental/Life
Electronic qualification test
New firmware
Unintended operation or not meeting
specification
Firmware test
13 NUDs
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NUDs and S30
Smart-Hub NUD list
NUD
Risk
Mitigation
Meet # of pushes
Analytics, testing if necessary.
Meet push force
Analytics, testing if necessary.
Linux operating system
METZ Connector
ESD
Gimbal
Environmental susceptibility
Durability and mounting strength.
Intended and reliable functionality
Corrosion, connection reliability
Electronic qualification test
Testing to be developed.
UV testing, thermal shock,
FEA
Firmware Testing
LR-805
Power Sequencer
Failure to process correctly during EMI.
Electronic qualification test
EMI, environment
Meet distance requirements
Meet brightness requirements
Clear becomes cloudy over time.
SD card becomes dislodged.
Meet Lennox life requirements
Thermal/mechanical stresses
Electronic qualification test
Testing to be developed.
Half Life calculation
UV testing, thermal shock,
Package testing, HALT
ALT
FEA, HALT, Thermal Shock.
Pushbutton Switch
2 wifi antenna
Plastic Housing
WIFI Radio
LED
Clear Plastic Lens
SD Card Holder Application
Life
PC Board
12 NUDs
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NUDs and S30
Comparison
Device
FMEA Lines (man
hrs)
NUDs (man hrs)
HD Display
290 (110)
9 (2.5)
Mag Mount
218 (60)
13 (1)
Smart Hub
274 (73)
12 (2)
782 (243)
34 (5.5)
Total
•
•
•
•
Brought to market 1 month earlier with higher confidence of reliability.
Warranty rate is lower than predecessor.
No warranty claims due to high risk items.
Identified unique manufacturing issues, magnet orientation.
Quicker than FMEA, higher confidence of reliability, early.
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NUDs
Pros/Cons of NUDs Method
• Pros:
−
−
−
−
−
−
−
−
−
Quicker path to identifying critical issues/components.
Efficient utilization of engineering and manufacturing resources.
Fewer team members to reach critical point.
Help guide engineering team to prioritize corrective actions.
Helps focus and prioritize FMEA process.
Actions underway on addressing high risk items at start of FMEA.
Help to reduce the time of project life cycle.
Identify risks at the beginning when costs of change are low.
Scales to scope of the project.
• Cons:
− Not 100% coverage as FMEA.
− Doesn’t necessarily include historical failure history data.
− There is a chance failure modes can be missed.
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Summary
•
•
•
•
•
•
•
NUDs: New, Unique, Difficult.
Uses block diagram, p-diagram.
Does not replace FMEA.
Identifies high risk issues at beginning of project with mitigation.
Efficient use of resources, (S30 3% of FMEA man hours).
Use for DFMEA, PFMEA, S&IFMEA.
Quicker to market, higher confidence of reliability.
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Speaker Bio
Joe Powell, Reliability Engineer, Fellow
Lennox International
Joe has been with Lennox for 31 years in various positions of design and management of electronic
controls and has spent the last 10 years in electronic control reliability. Previous to Lennox he worked in
electronic design at Ranco Electronics, Luminator, Northern Telecom. Joe holds an Associate and Bachelors
degree in Electrical Engineering and holds 8 patents.
Contact
joe.powell@lennoxind.com
214-460-3966
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Questions?
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