Instrument automatically and nondestructively monitors the quality of welds produced in microresistance welding. It measures the infrared energy generated in the weld as the weld is made and compares this energy with maximum and minimum limits of infrared energy values previously correlated with acceptable weld-strength tolerances

Deal, F. C.

English

NASA Technical Reports Server

September 1968	 Brief 68-10333 
NASA TECH BRIEF 
NASA Tech Briefs are issued to summarize specific innovations derived from the U.S. space program, 
to encourage their commercial application. Copies are available to the public at 15 cents each 
from the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia 22151. 
Automatic, Nondestructive Test Monitors ln : Process Weld Quality 
is
A new instrument, which has been developed, 
automatically and nondestructively monitors the 
quality of welds produced in the process of micro-
resistance welding of electronic assemblies. This 
instrument ensures 100 percent nondestructive inspec-
tion of the welds on every workpiece, as contrasted 
with conventional systems which involve either de-
structive or nondestructive tests on samples taken 
from the production line after the welding operation 
is completed. 
The new instrument automatically measures the 
infrared energy generated in the weld as the weld is 
made on each workpieëe and compares this energy 
with maximum and minimum limits of infrared 
energy values previously correlated with acceptable 
weld-strength tolerances. In the experimental correla-
tions performed on more than 17,000 welds of several 
wire combinations, infrared energy less than a certain 
value resulted in inadequate weld tensile strength, 
whereas excessive infrared energy resulted in weld 
expulsion. 
When the infrared energy measured by the instru-
ment is below or above the preset limits, a red indica-
tor light turns on, denoting an unacceptable weld. The 
instrument then locks out the welding system power 
supply, preventing further welding until the fault is 
determined. After the fault is determined and cor-
rected, the inspector can reset the instrument with a 
key, and welding can resume. When the measured
infrared energy falls between the preset limits, a green 
indicator light turns on momentarily, denoting an 
acceptable weld. 
Notes: 
I. This instrument can, in principle, be modified to 
provide an in-process, closed-loop, weld-control 
system. This system would control the shape of the 
weld pulse to ensure optimum weld strength. The 
system would include a computer incorporating a 
a generator of a predetermined infrared energy 
profile, a sensor of the infrared energy generated 
in the weld, and a welder whose output current 
would be controlled as a function of the difference 
between the infrared energy measured as the weld 
progresses and the standardized energy profile. 
2. Complete details may be obtained from: 
Technology Utilization Officer 
Marshall Space Flight Center 
Huntsville, Alabama 35812 
Reference: B68-10333 
Patent status: 
Inquiries about obtaining rights for the commercial 
use of this invention may be made to NASA, Code 
GP, Washington, D.C. 20546.
Source: F. C. Deal
of Martin Marietta Corporation

under contract to

Marshall Space Flight Center

(MFS-14996) 
Category 01 
This document was prepared under the sponsorship of the National
	 Government assumes any liability resulting from the use of the 
Aeronautics and Space Administration. Neither the United States
	 information contained in this document, or warrants that such use 
Government nor any person acting on behalf of the United States	 will be free from privately owned rights.
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Automatic, nondestructive test monitors in-process weld quality

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