1. WELDING IN WORKBENCH
Bruce Russell
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2. HISTORY
 In 1941 Orange Fowler Merwin sold
equipment to grain Millers
 Common complaints of stray metal in the
grain
 Devised a non-electric magnetic
separator in 1942
 Worked well enough, it developed into
product used today for the food industry
 130,000ft2 facility serves as
Headquarters in Erie, Pennsylvania
 Has sales offices all across the United
States and over 80 international markets
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3. Product: How it works
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4. Metal detector housing
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• Stainless steel
• Welded together
• Hollow walls aside from coil
• Rigid metal structure
• Hollow cavity filled with
foam and marbles
• Weighs 2400lbs

5. Problem
• Fill material cures, and
shrinks during the
curing process
• When end plate is
welded on, heat causes
foam to separate from
housing
• Rigid Metal zone is
compromised –
deflection of housing
registers as a false
metal detection.
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6. Problem – HOUSING
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• Initial weld on outer housing
• Causes thermal expansion of housing and foam

7. Housing Temperature
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8. Problem – FOAM
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• Heat transfer from welding arc is disbursed into the housing, and
then into the foam
• Properties of foam are compromised due to heat of weld

9. Foam Temperature
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10. Problem – PRESSURE FROM WELD
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• Weld increases negative pressure inside of housing
• Negative pressure increases likelihood of foam separating from
housing

11. Workbench Weld Command
D=.5 ! Desired length of weld
SP=-3.5 ! Start point of weld in axis
LL=6 ! Total length of weld
TTI=1 ! Time spent on current weld area
XYZ=Y ! Chose Plane that weld is in either X,Y or Z LEAVE QUOTES
Weld_1=Weld_A ! Enter Named Selection of Elements for Weld LEAVE QUOTES
! DO NOT ENTER OR CHANGE ANY DATA BELOW
CMSEL,S,Weld_1
eplot
EKILL,ALL
allsel
BFUNIF,TEMP,71.6 ! uniform initial TEMP
BFUNIF,HGEN,0 ! uniform intial heat generation
/PBF,HGEN,1
eplot
/USER
TIMINT,OFF ! 1st solve is steady-state to establish initial conditions
Time,0.001 ! for short duration (1 millisecond)
NSUBST,2 ! 02/26/2106 - use 2 substeps
solve
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12. Ansys Result - Current Fill Process
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• Simplified – all foam/marbles are in place initially (no weld
considered)
• Shows foam wants to pull away at the top of the housing
Contact Pressure, negative shows separation likely

13. Current Solution
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• Attach grease fitting
• Drill two pressure relief holes
• Pump full of epoxy until epoxy leaves pressure relief holes
Downsides
• New grease gun each housing – epoxy ruins grease gun
• Significant post processing – extra expenses

14. Goal: Eliminate possibility of foam
retracting from metal housing
How?
 Non-metal bracing inside housing (trusses/splints/ribs)
 Change the filling process of the housing
 Cool the marbles before filling process
 Heat the housing before/during the filling process
 Weld end plate with hole in it after 1st shot, instead of
at the end of the shot process
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15. Non-metal bracing inside
housing (trusses/splints/ribs)
 Adds rigidity to the housing
 Larger surface area for foam to adhere
to
 Has to be non-metallic
 Bracing will be slightly press fit into
housing
 Foam will hold bracing into place
 Investigate welding process
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16. Change the filling process of the housing
Current Process:
 Foam shots typically 15 seconds in duration
 Post foam shots executed randomly
 Random amount of marbles used per shot
Concept Process:
 Foam shots done one after another in strict equal intervals
 Foam shots done before previous shot is cured
 Equal amounts of marbles per shot
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17. Cool the marbles before filling process
 Will lower the chemical reaction temperature of the foam
 Without marbles, reaction temperature reaches 250 degrees
Fahrenheit
 With marbles, reaction temperature reaches 150 degrees
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Why wont cooling the marbles work?
• Proper cure temperature of foam is 78⁰F ambient temperature

18. • Expands housing larger than desired dimensions
• Once cooled, will conform to cured foam, creating
compression in the foam
• Slow the cure process of the foam
• Foam and Housing will shrink uniformly
Heat the housing before the filling process
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19. • Heat distribution of weld will be done
before foam is affected
• Perform shots through small hole in
the end plate
• Heat of weld to cap the hole will be
significantly less than entire end
plate
Weld end plate on after 1st shot,
instead of at the end of the shot
process
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20. Weld Analysis on end hole
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21. QUESTIONS?
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