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issue: July 2003 APPLIANCE Magazine

Testing Equipment
Appliances on Trial


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by David Simpson, Contributing Editor

Appliance companies use new technology and techniques to get more bang for their bucks in such areas as testing of electrical safety, coating thickness, dimensions, and refrigerant leaks.

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.


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.


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.


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.


“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.


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.


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.


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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