In today’s manufacturing
environment, improving product quality is often part and parcel of
broader efforts to achieve continuous improvements. Many manufacturers
have opted for a Six-Sigma approach, which can significantly shake
up manufacturing and other operational areas, while driving down unnecessary
costs.
For instance, Maytag Corporation
uses what it calls a LeanSigma approach in manufacturing. This identifies
ways to eliminate waste in operations, as well as variations in parts
and processes that can undermine product quality. It has been implemented
in a Jackson, TN, U.S. plant, transforming a half-mile long, continuous-line
dishwasher assembly operation. The line was split into seven separate
assembly cells capable of a wide range of product mix capabilities.
The effort freed up 43,000 sq ft of manufacturing space while improving
productivity by 22 percent. Not least of all, it also resulted in a
55-percent improvement in product quality.
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DeFelsko
Corporation (Ogdensburg, NY, U.S.) reports it provides
coating thickness gauges that are advanced, yet easy to
use. This is said to enable a manufacturer to have the
process control it needs without spending money to learn
how to understand the instrument.
One
model, the PosiTector 6000 FN, has the ability to measure
coatings on both steel and aluminum with the same probe.
This automatic substrate recognition, the company says, allows
the user to test coating thickness on all metals, reducing
confusion and possible operator error.
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As appliance companies
look at their manufacturing processes, they have a wide range of testing
equipment available to help them meet their goals. Technology continues
to advance, allowing improvements in accuracy, flexibility, record
keeping, ease of use, and even cost.
In powder coating,
for instance, Tennsco (Dickson, TN, U.S.) has benefited from using
new powder measuring technology. The company makes products such as
shelving, lockers, storage cabinets, filing cabinets, and workbenches.
It has six plants with a combined total of seven powder paint lines
and one e-coat line.
The company decided
to use an Elcometer 550 uncured powder thickness gauge from Rochester
Hills, MI, U.S.-based Elcometer
Inc. “It was first used in plant number five to establish
some baseline settings for the powder booth operators to use as a guide
for the proper booth settings,” says Johnnie Morris, plant manager
at plants five and six in Dickson, TN, U.S. The gauge has since made
its way to the other plants running powder to establish the same settings
and look for areas of excess coverage.
The probe, shaped
somewhat like a handgun, is positioned about 17 mm (3/4 in) from the
surface to be measured. LEDs on the probe and on the front panel of
the gauge indicate the position and alignment of the probe relative
to the surface. The readings are taken automatically when distance
and orientation are correct. The operator then pushes the measurement
button again to stop measuring. After approximately 1 sec, the gauge
will display the predicted cured powder coating thickness reading.
Prior to the company’s
acquisition of the new gauge, cured film measurement was about the
only option available. This meant that the company had to wait 45 min
until the parts left the bake oven. Now, the gauge gives instant knowledge. “You
can make powder adjustments on the fly, rather than waiting 45 min
for final confirmation of any adjustments,” says Mr. Morris.
He reports that the gauge works well, and that it required minimal
training. With the operating costs for each line, it didn’t take
too many hours of repaint savings to recoup the investment. That does
not even take into account
the powder savings incurred by getting the powder setting dialed in correctly
much faster than waiting for the first cured parts to become available for
inspection.
“We still
have a ways to go before I feel we are totally utilizing the one gun
we now have, but in time I feel we will probably purchase two more
guns so that each of our facilities spraying powder can have access
to their own gun,” says Mr. Morris. One
way to maximize testing efficiency is by combining multiple safety tests
into one workstation. Slaughter
Company (Ardmore, OK, U.S.) says its enhanced line of hipot testers
can be interconnected to its enhanced line of ground bond testers to
form a complete test system that will do the most commonly performed
electrical safety tests—a.c./d.c. hipot, insulation resistance,
and ground bond test.
“This allows these tests
to be performed through one connection to the Device Under Test (DUT),” observes
Tim Collins, sales coordinator. “Being able to perform these tests
in one DUT connection will increase efficiency. With one test station
and one test connection, products will be moved through the workstation
faster.
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White
Light Sensor (WLS) technology from Mycrona of North America
Inc. (Elgin, IL, U.S.) uses a white light sensor to scan points
on a part’s surface. The measuring principle of a WLS
for measuring heights is based on wavelength instead of intensity.
This reportedly results in several advantages compared to traditional
laser scanning, including the ability to scan diffuse surfaces
with up to 89 degrees of inclination, simultaneous measurement
of surface thickness, uninterrupted part scanning regardless
of surface roughness, reflectivity (mirrors, glass) or light
absorption (mat black surfaces), and the measurement of transparent
parts.
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“Secondly, one DUT connection
will yield more accurate results,” he continues. “With fewer
connections, there are fewer chances for a connection to be made incorrectly.
Tests are being performed at the same station, with the same operator,
and the same connections. This reduces possible discrepancies that could
occur if integrated tests were not performed at one test station.”
Dwayne Davis, technical services
manager at Associated
Research, Inc. (Lake Forest, IL, U.S.), reports seeing more use and
integration of multi-function instruments in production lines. “The
main advantage of using multi-function instruments is much more productivity
for a manufacturer,” he explains. “The combination of a.c./d.c.
hipot, insulation resistance, and ground bond in a single instrument
with one DUT connection will increase throughput by providing an efficient
testing process. Multiple connections to the DUT are not required.”
In addition to multi-function Dielectric Analyzers, customers can also choose
to integrate multiple test instruments with one DUT connection into a workstation,
says Mr. Davis. “This setup is usually chosen because the manufacturer
already owns some of the necessary equipment and simply wishes to add more
test capability. Although upgrading to a multi-function instrument is still
the preferred method, using linked testers can be effective in solving certain
test application problems,” he explains.
As an example, Mr. Davis tells
of a small home appliance producer that has an application requiring
a functional run test. This is designed to ensure that the manufactured
product will perform its intended functions. This test is normally performed
after a hipot test.
“The functional run tester,
which the manufacturer developed itself, included its own set of test
connections in addition to the test connections of the hipot tester,” Mr.
Davis explains. “After the hipot test, the manufacturer would perform
the functional run test without always disconnecting the test leads of
the hipot tester. This caused a failure in its hipot testers when a faulty
product was tested because line power was fed back into the return circuit
of the electrical safety tester.
“The repeated damage
to the hipot testers led us to review the application,” he continues. “Once
the problem was diagnosed, it was determined that it would be eliminated
by connecting an external functional run tester to the existing electrical
safety testers to allow one DUT connection. This eliminated the connection
issues, as the external functional run tester included an internal switching
matrix. This automatically disconnected the electrical safety tester
before the run test was performed. This manufacturer currently owns several
of our RUNCHEK stand-alone functional run testers. This solution saved
repair costs for the manufacturer while increasing productivity.”
Leak testing is one area where
appliance companies may face continued cost pressures because of increasingly
tight leak specifications. “Government regulations for environmental
protection and user safety, plus product validation against consumer
litigation are driving the specification changes,” reports Gary
Grebe, marketing director for Cincinnati
Test Systems (Village of Cleves, OH, U.S.). “This trend makes
it more difficult to provide an economical leak test solution to the
customer. The lower leak rate specifications are requiring the use of
more sensitive and more expensive tracer gas technologies like helium
mass spectrometers. These technologies are production-proven and successfully
applied in many industries. But they are more expensive than the traditional
pressure decay and mass flow technologies that are typically used.”
The solution, he says, is getting
the customer to budget and get approval for the higher expenditures required
to meet those specifications.
“In addition, as the
appliance producers assimilate the leak test function into their manufacturing
line as a process gauge, they want to identify causes for failure so
that they can improve their manufacturing process,” Mr. Grebe continues. “In
leak testing, that means identifying the leak location. At this time
that requires taking the reject parts out of the manufacturing process
and manually re-testing the part to visually identify the leak and keep
records. Because of the expense of performing this extra manual test,
there has been very little progress in closing this process control loop.”
One way appliance producers
could reduce their manufacturing costs is by providing a continuous feedback
from their leak test operation to their assembly operation, Mr. Grebe
offers. “This would require leak location identification by the
on-line leak test system,” he says. “This need to quantify
a part’s overall leak rate and simultaneously identify the leak
location has challenged leak test equipment manufacturers for decades.”
Enhanced Controls
Testing equipment is increasingly
involved in downloading data into networks. Says Christian Petrilli,
marketing manager for Fischer
Technology, Inc. (Windsor, CT. U.S.), “More and more of the
equipment on the production floors is ‘smart’ and can be
wired into a company’s network.”
As a result, he says, many
manufacturers capture information in real time to control production
and processes. “When it comes to coating thickness measurement
in the appliance industry, instruments are typically used near a paint
area, powder coating line, or plating line. This requires rugged hand-held
instruments capable of fast, accurate measurements with the capability
to download data to a network. Various models are available that feature
RS232 interfaces for downloading data to a networked PC. This enables
measurements to be taken in the production area, downloaded, and evaluated
for process control,” Mr. Petrilli explains.
“Even in today’s
slow economy when a piece of older test equipment wears out, replacing
it with something of current technology is still a viable option for
most appliance producers,” adds Jim Richards, marketing/applications
for QuadTech,
Inc. (Maynard, MA, U.S.). “Test equipment continues to advance
by offering more bang for the buck, meaning it can do more, do it better,
faster, and for less money. When purchasing test equipment, one caution
seems to be think beyond the needs of today. Don’t exclude test
capabilities, computer interface, or data logging ability that could
become future requirements in the testing process.”
Network capabilities are an
essential part of one quality trend observed by Karl Kohlhase, manager
of marketing services for ECI (Collierville, TN, U.S.). “The shipping
watchdog guarantees that consumers receive the best quality product manufacturers
can provide,” Mr. Kohlhase says. “An all-encompassing cross
check through all processes, our PackOut module is the final assurance
that each unit has passed all previous quality tests. No defect gets
through. Electrical interlocks prohibit final packing and shipping until
all tests have been passed. For instance, if the watchdog detected that
a unit bypassed a final leak test, the shrink-wrapping machine would
refuse to work for that serial number. This gives the consumer a consistent
level of quality-guaranteed.”
Mr. Kohlhase says that when
ECI first introduced the watchdog principle to its clients, there was
some resistance by operators who were concerned about meeting daily quotas.
But as management noticed the significant drop in warranty claims, it
was mandated in no uncertain terms that the watchdog could not be bypassed. “Our
customers have informed us that, with the aid of our Integrated Process
Control System (IPCS), they consistently approach zero DOAs (dead on
arrivals) and have dramatically reduced warranty claims,” he says. “In
one case of a very high-volume manufacturer, prior to installation of
an IPCS, the in-plant reject codes were in the 17 to18 percent range,
and in-field warranty claims were in the 5 to 6 percent range. After
the IPCS was put into place, the in-plant rejects sky-rocketed, and the
field claims basically went down to zero.”
As a result, the customer got
interested in determining what problems were causing these in-plant rejects. “With
our help it started eliminating problems one by one,” explains
Mr. Kohlhase. “It called in its suppliers and talked to them about
their component problems. It also improved the assembly process, the
drawings, and other factors that it found necessary to lower that reject
rate.
“As both of these rates
(in-plant and in-field rejects) approach zero, your profits will go up,” he
continues. “Add greater profits to increased customer satisfaction
and goodwill due to your commitment to quality, and you have a formula
for sustained success.”
The maker of the Jarvik 2000
artificial heart—technically referred to as a left ventricular
assist device—is now getting a manufacturing assist from the Sheffield
Discovery II Coordinate Measurement Machine (CMM). Dr. Robert Jarvik,
MD, inventor of the artificial heart, oversees development at Jarvik
Heart Inc. in New York, NY, U.S. The CMM, manufactured by Sheffield
Automation of Fond du Lac, WI, U.S., is an automated 3D measurement
device for high-precision manufactured parts.
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The
Jarvik 2000 device works as a complement to a heart’s
function. Production of the device required precision inspection
of the critical parts. Picture courtesy of Texas Heart® Institute.
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The Jarvik 2000, essentially
a miniature pump, has already been implanted in more than 40 patients
in the U.S. and Europe. Implanted inside the left ventricle, the device
pumps up to 6 L of oxygenated blood per minute through the heart, in
cooperation with the heart beat. In U.S. clinical trials, the Jarvik
2000 has been used as a bridge-to-transplant device, helping ill patients’ hearts
function until a donor heart is found. In Europe, the device has also
been implanted as a lifetime-use device for candidates unsuitable for
heart transplants. The first patient to receive the artificial heart
for this purpose is still surviving after more than 2 years on the device.
The artificial heart is approximately
the size of a “C” battery, fabricated primarily out of titanium
and ceramic components. The pumping action is valveless, operating by
means of a rotary impeller, which is suspended in the bloodstream and
spins on ceramic bearings using magnetic induction. The pump’s
blades spin at between 8,000 and 12,000 rpm, which is adjustable by the
users based on their level of physical activity.
Jarvik Heart manufactures many
of the critical parts itself, in a suite of offices in midtown Manhattan,
NY, U.S. It purchased the Discovery II CMM to assist with R&D and
manufacturing quality control. One hundred percent of the manufactured
parts are checked in all critical dimensions. According to Dr. Jarvik,
the company is now working on incremental improvements in the design,
manufacture, and assembly of the miniature components.
At first, Jarvik Heart was
looking for a vision machine, but found it limited for many of the parts
to be inspected, particularly precision conical forms. Sheffield representatives
instead showed Dr. Jarvik the Discovery II, which turned out to be well
suited. “We were looking for a versatile machine that was accurate,” says
Dr. Jarvik. “The main thing was for the inspection routine to be
fully motorized and automated. We wanted the program to run the inspection
and get away from any operator variation in the measured results.” The
fully CNC-controlled CMM, once programmed, can run repeatable measurements
with minimal operator input.
Another feature that was appealing
was the automatic temperature compensation—a standard feature on
all of the supplier’s CMMs. According to Dr. Jarvik, “The
machine is not located in a clean room, so the environment doesn’t
have the same degree of temperature control that a clean room would;
it’s probably plus or minus 2 degrees.” The CMM that Jarvik
uses is also equipped with an optional part thermistor to monitor and
compensate for the ambient temperature of the measured part itself.
Finally, the fact that the
CMM runs on high-precision, recirculating ball bearings and has no need
for an air supply like most other CMMs means that the user can locate
the machine anywhere, without regard for an air supply connection. In
fact, since the machine is on wheels, it can be moved to wherever it
is needed.
The long-term goal is to make
the Jarvik 2000 accessible to all cardiac surgery centers, so that many
more patients can benefit. The CCM can help Jarvik Heart Inc. ensure
consistently high-part quality as production volumes increase. The artificial
heart can help people with congestive heart failure enjoy better quality
of life and increased chance of survival. And that’s good news
by any measure.
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The
Discovery II Coordinate Measurement Machine (CMM) from Sheffield
Automation provides fully motorized and automated inspection
of critical components in the Jarvik 2000 artificial heart
device.
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