The Process
Capacitor Discharge
2
1
Stud against work
Stored energy discharged
through special
weld “timing” tip and stud
starts downward
Capacitor Discharge (CD) Stud Welding
is also a semi-automatic arc welding process.
However, with CD welding small diameter
fasteners (1/4" and under) are end welded to
ex tremely thin gauge parent metal. The CD
process operates on the principle of capacitor
stored energy which is instantaneously dis
charged by the equipment system through a
special weld “timing” tip. Since the entire weld
cycle is completed in several milliseconds,
welds can be made to thin sheet without pro
nounced distortion, burn-through or discol
oration. CD welding permits stud welding of
dissimilar metals.
4
3
Stud forced into
molten metal
Metal solidifies and
weld is completed in
a split second
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General Specifications
Capacitor Discharge
Arc
Standard in low carbon steel, 18-8
Standard in low carbon steel
stainless, and 1100, 6061, and 5000 series
aluminum. Brass and other grades of
stainless steel are also available.
and 18-8 stainless. Aluminum,
monel, inconel, and other grades
of stainless steel are available.
Copper plating is standard. Nickel,
Zinc to ASTM-B 633 (formerly
zinc, and other platings are available.
A 164) and other platings are available. Non-weldable plating is removed from the weld end to avoid
contamination of the weld.
Annealing:
All low carbon steel and stainless steel
studs are annealed where required.
Low carbon steel can be annealed
to a ma ximum of 75 Rockwell B
and stainless steel to a ma ximum
of 90 Rockwell B.
Threads:
UNC-2A is standard for ex ternal threads prior to plating and UNC-2B for internal threads.
Metric and other thread sizes are available.
Weld Base:
Flanged, small-flanged, and non-flanges
are available.
Material:
Plating:
/4" diameter and over have solid
flux. Diameters under 1/4" are
standard pointed, and flux is optional.
1
Stud Length: CD studs have no appreciable length
reduction af ter welding.
Stud Diameter
1
Ferrules:
Does not apply to CD.
3
1
/16" thru /2"
7 "
"
/8 thru /8
1" and over
1
5
3
/8" wide rectangulars
1
All orders include ferrules when
they are required.
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Approx.
Reduction
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/ 8"
/16"
1 "
/4
/8"
CD Stud/Base Metal Combination
Welding Capabilities
Base Weld
Surface Material
Mild Steel
1006 through 1030
Medium Carbon Steel
1030 through 1050
Galvanized Sheet Duct
Or Decking
Structural Steel
Stainless Steel
405, 410, 430, and 330 Series,
except 303
Lead Free Brass,
Electrolytic Copper,
Lead-Free Rolled Copper
Most Aluminum Alloys
Of The 1100, 3000, 5000, and
6000 Series**
Die-Cast Zinc Alloys
Stud Material
Mild Steel
1008, 1010
Stainless
304, 305
Aluminum
1100, 6061
Brass
70-30, 65-35
Excellent
Excellent
—
Excellent
Good*
Good*
—
Good*
Excellent
Excellent
—
—
Excellent
Excellent
—
Excellent
Excellent
Excellent
—
Excellent
Excellent
Excellent
—
Excellent
—
—
Excellent
—
Good*
Good*
Excellent
Good*
*Good: Generally full strength results, depending upon the
combination of stud sized and base metal.
**Other materials, such as 7000 Series aluminum, titanium
alloys, Inconel, etc. can be welded under specified conditions.
CD Stud Reverse-Side Marking
limitations
The charts on the following page will be of help
in determining the best combination of stud
weld base size and base metal thickness. The
terms on the chart are defined as follows:
EXCELLENT—
No marking, excellent
weld.
ACCEPTABLE—
Visible markings, excellent
weld.
UNACCEPTABLE— Unacceptable marking,
base metal failure.
It should be noted that these charts are based
on optimum laboratory conditions. Even under
optimum conditions, it is dif ficult to determine
the precise point at which reverse-side marking
will appear. Therefore, these charts should be
used only as a guide.
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How To Find The Optimum Combination
Of Stud Sized And Base Metal
Thickness In Order To Prevent
Reverse-Side Marking.
BASE METAL THICKNESS
.010"
.020"
.030"
.040"
4-40
4-40
Mild Steel
Stud: Mild Steel, Flanged or
22 TO 28
Small Flanged
14 GA. TO 25 GA.
16 GA. To 25 GA.
Stainless Steel
17 GA. TO 28 GA.
Base Metal: Stainless Steel
19 GA. TO 28 GA.
Stud: Stainless Steel, Flanged
or Small Flanged
22 TO 28
15 GA. TO 22 GA.
16 GA. TO 24 GA.
Aluminum
19 GA. TO 24 GA.
8-32
.010"
Acceptable
Base Metal: Mild Steel
10-24
4-40
Unacceptable
Excellent
1/4-20
6-32
.090"
22 TO 28
10-24
6-32
.080"
20 TO 25
1/4-20
8-32
.070"
19 TO 25
10-24
6-32
.060"
10 GA. TO 22 GA.
1/4-20
8-32
.050"
Base Metal: Aluminum
19 GA. TO 26 GA.
Stud: Aluminum, Flanged or
Small Flanged
21 TO 26
.020"
.030"
.040"
.050"
.060"
BASE METAL THICKNESS
.070"
.080"
.090"
Note: Stud tip size can influence the
degree of reverse-side marking.
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CD Stud Load Strengths
Maximum
Ultimate
Fastening
Tensile
Torque
Load
(Inch Lbs.)*
(Lbs.)
Maximum
Shear
Load
(Lbs.)
Stud
Material
Stud
Size
Low-Carbon,
Copper-Flashed
Steel
6-32
8-32
10-24
1/4-20
5/16-18
3/8-16
6
12
14
43
72
106
500
765
960
1750
2900
4300
375
575
720
1300
2200
3250
Stainless
Steel
6-32
8-32
10-24
1/4-20
5/16-18
3/8-16
10
20
23
75
126
106
790
1260
1530
2880
3750
4850
590
940
1150
2160
5350
7150
Aluminum
Alloy
1100
6-32
8-32
10-24
1/4-20
5/16-18
3/8-16
2.5
5
6.5
21.5
36
53
200
295
380
670
1125
1660
125
185
235
415
695
1000
Aluminum
Alloy
6061
6-32
8-32
10-24
1/4-20
5/16-18
3/8-16
6.5
13
19
40
70.5
100
350
560
670
1240
2025
2985
160
229
310
679
1210
1750
Brass
70-30 (260)
65-35 (268)
6-32
8-32
10-24
1/4-20
5/16-18
3/8-16
8
16
18.5
61
102
150
600
860
1040
1950
3280
4800
390
560
680
1275
2140
3160
*These values should develop fastener tension to
slightly less than yield point.
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CD Studs Weight Charts
ESTIMATED WEIGHTS OF THREADED STUDS IN POUNDS PER 1000 PIECES
LENGTH
4-40
6-32
8-32
10-24
1/4-20
5/16-18
1/4
.69
1.00
1.39
1.79
3.08
4.90
3/8
.94
1.38
1.93
2.50
4.37
6.98
1/2
1.18
1.76
2.49
3.21
5.66
9.06
5/8
1.43
2.13
3.04
3.93
6.95
11.13
3/4
1.67
2.51
3.60
4.64
8.24
13.21
7/8
1.92
2.89
4.15
5.35
9.52
15.29
1
2.16
3.26
4.71
6.07
10.81
17.36
1-1/4
2.65
4.02
5.82
7.50
13.39
21.52
1-1/2
3.15
4.77
6.93
8.92
15.96
25.67
1-3/4
3.64
5.52
8.04
10.35
18.54
29.83
2
4.13
6.27
9.15
11.78
21.12
33.98
2-1/4
4.62
7.03
10.26
13.21
23.69
38.14
2-1/2
5.11
7.78
11.37
14.63
27.27
42.29
EACH ADD’L INCH
1.96
3.01
4.44
5.71
10.31
16.62
ESTIMATED WEIGHTS OF NON-THREADED STUDS IN POUNDS PER 1000 PIECES
LENGTH
3/32
1/8
5-32
3/16
1/4
5/16
1/4
.68
1.06
1.59
2.24
3.87
5.97
3/8
.92
1.50
2.27
3.21
5.61
8.68
1/2
1.16
1.93
2.94
4.19
7.35
11.39
5/8
1.40
2.37
3.62
5.16
9.09
14.11
3/4
1.64
2.80
4.30
6.14
10.84
16.82
7/8
1.88
3.24
4.98
7.12
12.56
19.53
1
2.12
3.67
5.65
8.09
14.32
22.25
1-1/4
2.60
4.54
7.01
10.04
17.81
27.67
1-1/2
3.08
5.41
8.36
11.99
21.69
33.10
1-3/4
3.56
6.28
9.72
13.95
24.78
38.52
2
4.04
7.15
11.07
15.90
28.25
43.95
2-1/4
4.52
8.02
12.43
17.85
31.75
49.37
2-1/2
5.00
8.89
13.78
19.80
35.23
54.80
EACH ADD’L INCH
1.96
3.48
5.42
7.81
13.94
21.70
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STUD WELDING PRODUCTS
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Hayward, CA 94545
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Downey, CA 90242
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STUD WELDING PRODUCTS
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Seattle, WA 98108
(206) 764-4561
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71
72
73
74
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Customer to specify material grade and stud type - Flanged or Non-Flanged
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Customer to specify material grade and stud type - Flanged or Non-Flanged
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Flanged Capacitor Discharge
weld-stud
Material: Mild steel, stainless steel, aluminum, brass.
STUD
Plating: All mild steel studs are copper plated.
Annealing: All studs are annealed.
D
2-56
H
.125
MIN
L
.250
4-40
.175
.250
6-32
.200
.250
8-32
.220
.250
10-32
.250
.250
10-24
.250
.250
1/4-20
.312
.375
5/16-18
.375
.500
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Non-Flanged
Capacitor Discharge
weld stud
Material: Mild steel, stainless steel, aluminum, brass.
STUD
Plating: All mild steel studs are copper plated.
Annealing: All studs are annealed.
D
4-40
6-32
8-32
10-32
10-24
1/4-20
5/16-18
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H
.112
.137
.163
.187
.187
.250
.312
MIN
L
.250
.250
.250
.250
.250
.375
.500
Small Flanged
Capacitor Discharge
weld stud
Material: Mild steel, stainless steel, aluminum, brass.
Plating: All mild steel studs are copper plated.
Nickel plating available.
Annealing: All studs are annealed where required.
STUD
D
4-40
H
.142
MIN
L
.250
6-32
.168
.250
8-32
.194
.250
10-32
.220
.250
10-24
.220
.250
1/4-20
.280
.375
5/16-18
.342
.500
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