Process control in electron beam welding is typically based on control of machine settings, such as accelerating voltage, beam current, focus coil current, and vacuum level. These settings, though important, provide little insight into the characteristics of the beam used to make the weld. With the enhanced modified Faraday cup (EMFC) diagnostic tool, these beam characteristics, including the peak power density, full width at half maximum, and full width at $1∕e2$ values, can be quantified. The use of this diagnostic tool in an extended production run at Lawrence Livermore National Laboratory (LLNL) is described. Results show that machine performance, in terms of these measured beam characteristics, varies over time when the EMFC is not used to adjust the machine settings. Testing has shown that the variability of the beam characteristics can be measurably decreased with the use of the EMFC diagnostic tool. With the implementation of this diagnostic tool in the process control procedures, every electron beam weld, which encompassed approximately 90 welds over an $18month$ time frame, met all of the requirements defined in the weld process specification and passed all of the postweld quality control checks. The results also show that variations in each of the measured beam parameters can be controlled at levels below $±2.2%$, which is smaller than the 5% tolerance band suggested by ASME for other welding parameters. Such an enhanced level of control allows product throughput to be increased by decreasing the number of rejected parts through the elimination of unexpected variations in beam characteristics. The benefits of integrating this diagnostic tool into future process control regimes are also discussed.

1.
2004, “
Recommended Practices for Electron Beam Welding
,” AWS C7.1M/C7.1:2004,
American Welding Society
, Miami, FL.
2.
Anderl
,
P.
, and
Scheffels
,
W.
, 1992, “
Process Control for Electron Beam Welding
,”
Weld. World
0043-2288,
30
(
5/6
), pp.
138
144
.
3.
LaFlamme
,
G. R.
, and
Powers
,
D. E.
, 1991, “
Diagnostic Device Quantifies, Defines Geometric Characteristics of Electron Beams
,”
Weld. J. (Miami, FL, U.S.)
0043-2296,
70
(
10
), pp.
33
40
.
4.
Dilthey
,
U.
, and
Weiser
,
J.
, 1995, “
Study of the Electron Beam ‘Tool'—Part 2: Effects on the Welding Result
,”
Schweissen Schneiden
0036-7184,
47
(
7
), pp.
558
564
.
5.
Dilthey
,
U.
, and
Weiser
,
J.
, 2001, “
Study of the Electron Beam ‘Tool'—Part 1: Comparison Between the Area Beam Test and Diabeam Beam Measurements
,”
Schweissen Schneiden
0036-7184,
47
(
5
), pp.
339
345
.
6.
Elmer
,
J. W.
, and
Teruya
,
A. T.
, 2001, “
An Enhanced Faraday Cup for the Rapid Determination of the power Density Distribution in Electron Beams
,”
Weld. J. (Miami, FL, U.S.)
0043-2296,
80
(
12
), pp.
288s
295s
.
7.
Elmer
,
J. W.
, and
Teruya
,
A. T.
, 1998, “
Fast Method for Measuring Power-Density Distribution of Non-Circular and Irregular Electron Beams
,”
Sci. Technol. Weld. Joining
1362-1718,
3
(
2
), pp.
51
58
.
8.
Elmer
,
J. W.
,
Teruya
,
A. T.
, and
O’Brien
,
D. W.
, 1993, “
Tomographic Imaging of Non-Circular and Irregular Electron Beam Power Density Distributions
,”
Weld. J. (Miami, FL, U.S.)
0043-2296,
72
(
11
), pp.
493s
505s
.
9.
Teruya
,
A. T.
,
Elmer
,
J.
, and
O’Brien
,
D.
, 1991,
The Laser and Electron Beam in Welding, Cutting, and Surface Treatment: State-of-the-Art 1991
,
Bakish Materials Corporation
,
Englewood, NJ
, pp.
125
140
.
10.
Dilthey
,
U.
, 2005,
,
N.
Ahmed
, ed.,
CRC
,
Boca Raton, FL
, pp.
198
228
.
11.
Nello
,
O.
, “
Electron Beam Probing Systems—A Review
,” TWI Bulletin, May/June, pp.
38
40
.
12.
Palmer
,
T. A.
, and
Elmer
,
J. W.
, 2007, “
Characterization of Electron Beams at Different Focus Settings and Work Distances in Multiple Welders Using the Enhanced Modified Faraday Cup
,”
Sci. Technol. Weld. Joining
1362-1718,
12
(
2
), pp.
161
174
.
13.
Palmer
,
T. A.
,
Elmer
,
J. W.
,
Nicklas
,
K. D.
, and
Mustaleski
,
T.
, 2007, “
Transferring Electron Beam Welding Parameters Using the Enhanced Modified Faraday Cup
,”
Weld. J. (Miami, FL, U.S.)
0043-2296,
86
(
12
),
388s
398s
.
14.
ASME Boiler and Pressure Vessel Code, Sections VIII and IX.
15.
Ross
,
P. J.
, 1998,
Taguchi Techniques for Quality Engineering: Loss Function, Orthogonal Experiments, Parameter and Tolerance Design
,
McGraw-Hill
,
New York
.
16.
Elmer
,
J. W.
,
Teruya
,
A. T.
, and
Palmer
,
T. A.
, 2002, “
User’s Guide: An Enhanced Modified Faraday Cup for the Profiling of the Power Density Distribution in Electron Beams
,” Lawrence Livermore National Laboratory Document UCRL-MA-148830, Livermore, CA.