Transcript Butt Joint with Backing - Utah Valley University | uvu.edu

Weld Types - Lap Weld
UVU CRT 2009
Lap Weld
 Many automotive
structural panels
are assembled
using a lap joint.
 Technicians must
 make test welds
 visually inspect
 destructively test
“before welding on the
vehicle”
UVU CRT 2009
Lap Weld Example
One side of the rail is crimped
to fit flush inside the other.
These are the crimping
tools. Notice the offset jaws
Relief cuts are also made at
the seams.
UVU CRT 2009
Lap Weld Fit Up
This is the backside of the
rail showing the overlap.
The crimp allows the panels
to fit flush.
UVU CRT 2009
Lap Weld
 You should now have an understanding
of what a lap weld is and where it is
used.
 The next step is to tune the welder and
perform a lap weld that will be
evaluated visually and destructively.
UVU CRT 2009
Lap Weld – In Class Assignment
 Joins two pieces of
overlapped metal
 Used for sectioning
rails and pillars
 Always follow
manufacturers
recommendation
UVU CRT 2009
Getting Ready to Weld
1” to 1.5”
Overlap ½ way
 Set one 3”x5”
coupon on top of
the other.
 Overlap ½ way.
 Mark 1” to 1.5” in
the center of the
coupon.
 The crimp is not
necessary on these
coupons.
UVU CRT 2009
Gun Position
70
90
90
 The proper gun to
work piece angle
for a lap joint is 70
degrees off the
surface.
 Angle the wire into
the top piece
UVU CRT 2009
Tune the Welder
 Make sure to “Tune the Welder” by
making practice welds on the same
material that will be used for the final
weld.
 Make the necessary voltage and wire
speed adjustments and check for proper
penetration before beginning the final
weld.
UVU CRT 2009
Lab Assignment
 Print off the Lap Weld “Task
Performance Sheet”
 Set up and tune the welder.
 Set up and mark the coupons for the
weld.
 Perform the Lap Weld.
 Visually inspect the weld.
 Destructively test the weld.
UVU CRT 2009
Visual Inspection
Length = 1” to 1.5”
Melt Through = 1/16” max.
Bead width = 3/16” to 3/8”
Height = 0” to 1/8”
Check for penetration on back of
coupons
UVU CRT 2009
Using I-Car’s WQT Gauge
 I-Car has provided
a gauge to help in
visually inspecting
welds for:





bead length
width
height
penetration
defects
UVU CRT 2009
Using I-Car’s WQT Gauge
Weld Bead Length
Weld Bead Width
UVU CRT 2009
Lap Weld Visual
Weld Penetration
UVU CRT 2009
Record the Results
 After the visual inspection is complete
record the results on the task
performance sheet and have the
instructor verify your results.
 Now the destructive test will need to be
performed.
UVU CRT 2009
Destructive Weld Test
 Secure bottom coupon in vise.
 Bend top piece back and forth until the
coupons separate.
 The metal should break along the length
of the weld.
UVU CRT 2009
Destructive Test
Metal from top piece
Notice the torn section – This is a sign of a
good weld
The weld is good if the metal breaks
off from the top piece.
UVU CRT 2009
Weld
 When the welds pass the visual and
destructive test observe the final voltage
and wire speed setting.
 Have the instructor check off your task
performance sheet.
 Complete your final weld series in the
flat vertical and overhead position.
 Turn these in for final grading.
UVU CRT 2009
References
 Miller Electric Mfg. Co. Education.
http://www.millerwelds.com/education/library.html,
2006.
 Lincoln Electric Co. Lincoln Welders.
http://www.lincolnelectric.com/, 2006.
 Inter Industry Conference on Automotive Collision
Repair. I-CAR Online Training. http://www.i-car.com/,
2006.
UVU CRT 2009