H
VXI Tests Swedish Company’s
Welding Machines
Manufacturing Test
Case Study
Customer:
ESAB Welding Equipment AB of
Sweden, one of the world’s leading
manufacturers of professional
welding machines.
Introduction:
Professional quality welding
machines are used in virtually every
phase of manufacture -- from home
appliances to automotive and
aircraft to steel mills and
shipbuilding yards to nuclear power
plants. ESAB designs and produces
a variety of these systems, including
manual and semi-manual machines,
fully automatic welding systems,
and individual units for hobbyists.
Situation:
During the past few years, the test
group at ESAB’s division for
standard welding machines has
worked with automated test
equipment (ATE) to conduct final
testing of its products. The first
ATE systems were bought turnkey
from external consulting companies
who put together unique
configurations for each product. At
first, these systems worked well.
Solution:
HP VXI was chosen exclusively for
the new test systems. The first one
built was for final testing of ESAB’s
new small rectifier for manual
welding -- the Caddy 110/150.
This test system was specified to
manage welding currents up to
200 amps. The next four systems
were designed for functional test of
PCBs -- three in Electronic
Production, and one in the AfterSales department for testing PCBs
sent in for repair. A final system is
used to test ESAB's new wire
feeders. HP VEE was selected for
test development after evaluation of
several graphical programming
languages. ESAB considered
HP VEE the easiest to get started
with. ESAB also installed a custom
test executive from HewlettPackard with the help of HP’s
consulting service.
HP was chosen as the supplier
because of its excellent reputation
for knowledge and support.
Description of Test:
The following is the test sequence
of the Caddy 110/150 test system,
which tests entire welding
machines. The test sequence is
as follows:
• Current consumption
• Internal voltage levels
• Thermal switch simulation
• Output current under various
loads
Test data is saved in a database on
LAN if the welding system passes
the test. A fail report is generated
if it fails.
Results:
Through the use of HP VXI and
HP VEE, ESAB’s test group is now
building and maintaining its own inhouse test systems. Today, it has
several VXI-based systems running
on different production lines. This
has opened up new possibilities for
controlling and testing products.
ESAB's expenses for the VXI test
systems are almost all hardware,
with very little in integrating
Barcode Scanner
Computer
Printer
Interface
Implications:
If the company’s welding machines
were not routinely tested, it would
not be known if they were in good
working condition when shipped to
customers. If defective units were
sent out, they would malfunction,
customer quality issues would arise,
and damage would result to ESAB’s
excellent reputation for quality.
Other companies would eventually
step in and erode the company’s
customer base.
HP's consulting service also helped
with the first test plan for the Caddy
110/150, and with implementing the
CAN interface -- a special
“broadcast” bus developed
specifically by the car industry and
used in place of the normal RS-232.
HP VXI
DUT
Slot Ø
VXI E1302A
Command E1306A
DMM 1328B
MUX 1343A
MUX 1343A
D/A E1328A
Relay E1364A
Switching System
Primary Main Unit
Secondary Unit
Load Unit 200A
Short Circuit Unit
Problem:
Eventually, however, the systems
became inflexible as products
changed. In order to achieve more
flexible production and eliminate
the need for external help at
product switchout, ESAB decided
to acquire the knowledge to build
test systems on its own. An
important requirement was that the
new systems had to be modular so
as to be readily changeable.
Another was that they had to be
insensitive to noise and vibration.
Configuration:
Computer
PC (AST P100)
VXI
HP E1302A B-size 20-slot VXI mainframe
HP 1306A HP-IB command module
HP E1326B 5.5-digit digital multimeter
HP E1328A D/A converter
HP E1343A 16-ch relay MUX
HP E1364A 16-ch Form C switch
Peripherals
Thermal printer (Setron)
Software
HP VEE
Other
HP 82345B automation kit
Power switch unit (Pickering Interfaces)
systems, as before. The time for
creating systems is minimal,
eliminating most of the
administrative cost for the
operators -- previous test systems
required operators to write test
protocol by hand. All that is now
handled by the test executive,
saving time and helping to ensure
higher quality of the final product.
Since ESAB has several systems
built with nearly the same
components, the company is no
longer vulnerable if, say, a single
instrument goes down and has to be
sent out for repair. The company
has not had a single stoppage on
any new VXI system that could not
be fixed immediately.
About 30 test plans have been
developed for testing printed circuit
boards and final products during
the two years the systems have
been up and running. This was
largely made possible by the
extreme versatility and ease of use
of HP VEE.
©1998 Hewlett-Packard Company
Printed in U.S.A. 07/98
0000-0000EUS