Testing Equipment
Appliances for the Long Term

by David Simpson, Contributing Editor

Developments in testing equipment help keep appliances looking good and performing perfectly long after they leave the factory.

The Lightning leak detector from FasTest, Inc. (St. Paul, MN, U.S.) performs pressure decay leak testing, sensing pressure changes to 0.00005 psi. It is said to reduce test cycle times by 80 percent and can be a valuable alternative to water-dunk and bubble testing. The detector reportedly provides easy-to-read self-diagnostic messages and setup procedures and can be integrated into a fully automated system. Test results can then be downloaded onto a computer or PDA for analysis.

In the appliance industry, testing can head off conditions such as electrical or other safety faults, mismatched colors, leaking refrigerant, “dead-on-arrival” situations, or a host of other problems. Just as important, testing can improve plant operation by assuring that production processes are running properly and supplied parts or components meet factory specs. Documented testing can also play a role in defending an appliance producer in product liability suits.

In appliance product testing, the use of electronics continues to climb. Much of today’s testing equipment offers more precision and flexibility than ever before, often through the replacement of analog with digital technology. Interaction with computer systems allows gathered data to be organized and available immediately in remote locations. In addition, ease of use has been improved, again with an assist from digital technology that makes possible such features as menu-driven interactive displays. Today’s technology also lends itself better to automation.

While automated testing is not for every company, Dwayne Davis, technical services manager of Associated Research, Inc. (Lake Forest, IL, U.S.), says that automation makes it much easier for a manufacturer to record and analyze test data. “Recording test data can be of significant value in determining testing trends and ensuring high quality standards,” Mr. Davis tells APPLIANCE. “Automation allows test data to be viewed in a graphic or detailed format, stored in an ASCII format, or exported to any database or spreadsheet program. Depending on the requirements of the manufacturer, this can be a great benefit. Storing data is a much better solution than manual recording of pass/fail statistics. A manual process of recording data many times can result in a loss of productivity, and a manufacturer might have a hard time accounting for operator error. Data capture practically eliminates these errors.”

Enjoying More for Less

With the return of growth in the appliance market, a number of appliance producers are studying means of obtaining more output from their facilities and staff. Long-term growth is, as always, dependent on meeting the demand for better performance and more reliable products at a lower cost. Sotcher Measurement Inc. of San Jose, CA, U.S. says it is finding a sudden spike in orders from its long-term customers that are looking to adjust their facilities to the new realities.

Marc Sotcher, president and CEO of Sotcher Measurement, adds that he is seeing a shift in specifications from testing products that just perform the compliance-type testing, such as hi-pot and ground wire continuity, to much more comprehensive evaluation of the product’s performance and reliability. Mr. Sotcher notes that there is more emphasis on self-testing and labor-saving test programs. “With today’s advances in technology, appliance makers are finding they can have the cake while eating it too,” he says. “They can have the benefits of a more comprehensive evaluation of their products, while enjoying a saving in labor costs.”

Mr. Sotcher says that customers such as BSH Bosch und Siemens Hausgeräte GmbH are integrating all the test bays and conveyor lines into their SAP networks. “The up-to-the-minute flow of data from the test stations is immediately available to the plant management in a clean concise format,” he explains. In other examples, Mr. Sotcher points to the subassembly test bay his company provides to BSH that not only reads the features installed on an appliance and then programs the control panel, but also sequences it through a full functional test and electrical safety test. “This allows the appliance maker to use one standard control panel for all appliances of similar type,” Mr. Sotcher explains.

He also points to continued growth opportunities that companies such as garbage disposal maker In-Sink-Erator are enjoying in countries like Japan. With its experience in overseas test requirements, Mr. Sotcher says his company allows the testing bays to be specified and built in the U.S. for use in Japan. As with most products they export, the operator information is displayed on a touch screen in the local language.

Mr. Sotcher notes that while such results were possible in the past, the result would often be a large and very expensive test system. The appliance producer could hire a system integrator to purchase a collection of test equipment, computers, and interfaces. The integrator would then program the collection of items to meet the needs of the situation. The time required to create such a test station, plus the costs of adapting it to the continued changing needs, limited the application of such systems to only the largest and most stable production lines.

“Testing equipment companies are now able to create test stations using small modules and existing software programs and create a fully automatic test station to evaluate the performance as well as the safety of a very wide range of products, providing the operator instructions and statistical data all in languages selected by the operator,” he explains.

Warranty Documentation

Addressing warranty claims is an important reason to consider full-function production testing, says Karl Kohlhase, marketing services manager of ECI (Collierville, TN, U.S.). “When done correctly, this kind of testing can slash warranty costs by as much as 90 percent or better, since defects are caught in the plant rather than in the field. In addition, our clients have reported returns on investment in as little as 5 months to a year,” Mr. Kohlhase explains.

Using the company’s AutoTest product, typical tests include hi-pot, ground continuity, ground bond, low-voltage start, starting and run current, compressor overload, cooling/heating temperatures, suction and discharge pressure, unit vibration test, unit voltage, current and power, four-way valve operation, 24 V a.c. winding check, wiring harness verification, gas-flow rate, and individual component current. An automated, computer-controlled sequence of operation eliminates operator dependency. All collected test data for each piece of equipment are automatically written to the database per serial number for quality control tracking.

“The only way to prove that an appliance was properly tested is through documentation,” affirms John Barnett, operations manager at Clare Instruments (Worthing, England). “With conventional manual recording systems being fraught with potential errors and problems, the most effective way to prove compliance with relevant standards is to use test instrumentation that not only automates the test process, but is also capable of recording the results at the same time. As well as storing results for later printout or downloading to a PC, such systems can be combined with pass/fail label printers complete with serial numbers and/or linked to bar code identification,” he explains.

Mr. Barnett adds that networking with central management information systems can allow the test station to become an important data collection point, not only in identifying failure rates, but also by providing details of productivity levels and other information as part of quality audit trails.

“There is also evidence that the costs of warranty claims can be reduced significantly by linking 100-percent production line testing with full traceability,” Mr. Barnett notes. “In the appliance producing industry, for example, there are examples of warranty costs being reduced by 90 percent with introduction of an integrated fully traceable safety testing system.”

However, while sophisticated equipment and automation have their place in appliance production, speed and simplicity are also key concepts. According to Jim Richards, marketing/applications at QuadTech, Inc. (Maynard, MA. U.S.), for most applications in the electrical safety area, handling a large quantity of product and arriving at a clear pass/fail end result is critical.

“In some processes, the move to automation is underway, but in others, operator activation (manual testing) is still alive and well,” Mr. Richards says. “Appliance producers tend to lean toward the rather basic, low-cost testers, where the bells and whistles are generally not required. Cost considerations become an important factor when multiple test stations are to be employed. There is some movement toward data logging of test results, more commonly found in an R&D setting, but in the production environment, there has to be a compelling reason to justify adding time and cost to the testing process.”

Atlas Material Testing Technology LLC (Chicago, IL, U.S.) has introduced extra-large cyclic corrosion cabinets with true testing volume of 110 cu ft/3,120 L. This is said to allow testing of fully assembled components to real-world conditions and more samples to be tested under identical conditions, eliminating the variables that occur with multiple chambers. The new cabinets can hold more than 900 standard test panels. One model is the BCX11000, or the Basic Cyclic Corrosion Cabinet, and another is the CCX11000, or Advanced Cyclic Corrosion Cabinet. Standard features include air-assisted cover lifters and four Omni-Fog II dispersion towers. Both models can be equipped with additional options.

Vibration: Good or Bad?

Cost pressures have also affected the testing of motor noise and vibration for the domestic and foreign appliance industries, notes Robert Mihata, president of Alta Solutions (Escondido, CA, U.S.). “The push to reduce costs in general has lowered noise and vibration quality standards for appliance sub-components,” he warns. “Both cheaper materials that have larger tolerances and increased outsourced labor have resulted in a wide range of manufacturing problems. Appliance makers use our testing equipment to produce quieter devices that vibrate less. The value of better-performing products can be easily seen in how today’s higher-end appliance market commands premium prices.”

Still, in many appliance motor applications, noise and vibration testing continues to be fairly low tech. “The vibration testing generally performed is having operators catch defective products by holding up each part to their ears, listening for subtle noise differences,” says Mr. Mihata.

In one medical motor application, Emerson Motor Technologies (St. Louis, MO, U.S.) was concerned with this subjective approach, although the company notes that low labor skills and large materials tolerances were not factors in this case. The company instituted a pilot program that uses an Alta Solutions system to test for noise and vibration in electric a.c. gear motors. Results after just more than 6 months are promising. “Taking a Six Sigma approach, we exhaustively studied the motors, looking at vibration at different frequencies and searching for potential causes for noise,” says Blake Vogt, Emerson’s manufacturing engineer. “We then developed a statistical mask using the Alta Solutions equipment. This mask represents an ideal motor, showing what the vibration profile should look like. Now motors are tested at the end of the line to see if they meet the standard. If vibration pierces the masks, the tester gets a light or buzzer to warn that there is an issue.”

Testing takes only about 5 sec. “We believe that since there will be fewer customer rejects, on balance the benefits far outweigh the cost of implementation,” says Mr. Vogt. If the customer questions whether a motor meets the standard, the portable test equipment can be transported to the customer’s site.

While inappropriate vibration in an appliance can lead to noise and even product damage, vibration also plays a useful role in appliance testing. According to Jeffrey Marshall, vice president of M/RAD Corporation (Woburn, MA, U.S.), a company may choose to utilize vibration as a method to qualify the design of a product. This, he says, ensures that a product can withstand critical frequencies, without failure, before it is released for production. “It is not uncommon, for example, to determine that a PC board exhibits a resonant frequency, which may cause it to mesh with other items in the chassis, thereby causing damage,” says Mr. Marshall. “The solution could be to add a brace or stiffener to solve the problem. Or perhaps, an entire electronics console filled with product may react unfavorably to vibration, creating a need for redesign.”

Another domain for mechanical shakers is in the simulation of vibration environments. The vibration profile required to simulate an airplane, ocean vessel, or truck is different and often requires a field-performed signature analysis or the guidance of a specification to duplicate these vibrations in a laboratory. There are myriad military and commercial specifications, which either suggest or mandate vibration levels for all environments.

“A popular use for mechanical shakers is to weed out manufacturing defects, such as excess solder and loose screws, during production,” Mr. Marshall adds. “This process is called Environmental Stress Screening (ESS), where the product is stimulated, as opposed to simulated. In this regard, it is intended to ultimately build from component to finished product with zero defects.”

According to Mr. Marshall, the success of the mechanical shaker in an ESS application is dependent on the fact that the shaker, in all probability, has enough performance (force, displacement, and acceleration) to damage a product. “If the shaker is capable of inducing failure and all aspects of the shaker are adjustable (which they are), then there may be a lesser vibration level in which manufacturing defects will occur,” he says.

Many industries have started switching to coated plastic parts in lieu of metal parts to reduce weight and cost. The PosiTector 200, reports DeFelsko Corporation (Ogdensburg, NY, U.S.) is an easy-to-use, affordable gauge for non-destructive measurement of coating thickness on non-metals, including plastics. The palm-sized model is designed to measure coatings including paint, varnish, and lacquer. The non-destructive unit is said to eliminate the need to repair coatings or scrap parts in order to accurately measure their coating thickness. Its non-destructive ultrasonic technique conforms to ASTM D6132.

Uncovering Small Leaks

Global competition and tighter environmental regulations have some manufacturers of refrigeration and air-conditioning equipment (RAC) second guessing the traditional methods of leak detection, suggests James T. Brown, product marketing manager, Leak Detection at Pfeiffer Vacuum Inc. (Nashua, NH, U.S.). He believes the more “environmentally friendly” refrigerants used today are less efficient and more expensive than the older, ozone-depleting CFCs (chlorofluorocarbons). This, Mr. Brown says, has resulted in the need to ensure that RAC systems and subassemblies meet more stringent leak test specifications. With the goal of improving product quality, lowering warranty expenses, and ensuring that products are accepted worldwide, manufacturing companies are replacing less-effective methods of leak testing with helium leak test equipment.

“The widespread popularity of helium leak testing within the RAC industry has been driven by the fact that it is a simple, extremely versatile, non-destructive method that provides the ability to quickly and accurately locate and measure very small leaks,” summarizes Mr. Brown. “In addition, the equipment is relatively easy to operate and requires little operator judgement. Helium leak detection is more sensitive, more accurate, and more repeatable than the water immersion bubble and rate-of-rise test methods.”

In fact, helium leak detection has become the de facto standard for air-conditioning and refrigeration system manufacturers, says Andy Moscarelli, vice president of Engineering at Serv-I-Quip (Downingtown, PA, U.S.). Helium leak detection methodologies, he says, provide a greater level of sensitivity for finding smaller leaks. The combination of helium’s smaller molecule size versus air or refrigerant, and a mass spectrometer-based sniffer with 10-6cc/yr leak rate sensitivity, and fast-response time versus other leak detection methodologies (pressure decay, water bath, etc.), provide a high-quality test.

“Helium is a by-product of natural gas production, and while its use as a tracer gas for leak detection is rising, the worldwide supply is not,” Mr. Moscarelli explains. “Bulk helium prices increased as much as 20 percent last year, and may increase even more this year. This has resulted in more interest in helium recovery systems. With this kind of system, if you are using U.S. $150,000 annually in helium, a recovery system is easily cost justified.”

Previously, lower volume helium users could not cost justify a helium recovery system, he adds. With this in mind, Serv-I-Quip has developed a system with lower recovery capacities, while maintaining all of the features of its other recovery systems. Mr. Moscarelli explains: “Customers are requiring helium recovery systems that have smaller recovery capacities because the return on investment is justifiable on smaller amounts of helium usage due to increased helium costs.”

In a helium leak testing system, connector performance is critical. The seal material must not allow helium to permeate, absorb, or out-gas. “The challenge is to provide a material that is compatible with the rigorous applications required by customers,” points out Bill Racine, president of Ramer Products, Inc. (Niles, MI, U.S.). “The rubber seal must provide a leak-free connection. Oils, refrigerants, high temperatures, and trace gases are just a few of the considerations when selecting a seal material. Also, customers and their test-engineering consultants are constantly coming up with new test methods that challenge connector design and material selection.”

One challenging application is provided by Danfoss, which makes commercial air-conditioner compressors in Lawrenceville, GA, U.S. “We first do a pressure test to 465 psi, and then add helium and air,” says Associate Engineer Steve Armour. “We pull a vacuum around the compressor, and measure the helium. But many of the leaks that were found by our helium tester were caused by the connection.”

About a year-and-a-half ago, the company went to Ramer for connectors. The compressor maker now has four connector sizes and is working on getting fittings for all of the sizes it uses. Each connector has an ID seal. “There has been a great decrease in helium detection due to what we call ‘non-leaks,’ which are primarily caused by helium leaks through the connectors,” Mr. Armour says.

Combining Tests

While ground bond tests on the production line are now required by a number of safety agencies, U.S. agencies only require a basic continuity test, observes Tim Collins, sales coordinator at Slaughter Company (Lake Forest, IL, U.S.). However, as the economy becomes more global, products need to meet safety requirements for both U.S. and international agencies. Not surprisingly, some manufacturers are implementing a ground bond test into their workstations in order to comply with all international standards.

“Manufacturers want to test their products in the most efficient manner possible and as a result, same-station electrical safety testing is being performed,” Mr. Collins says. “In the past, a production line might have had one station that performed a ground bond test and another that performed a hi-pot test. This meant that as the device under test (DUT) went from station to station, test leads needed to be removed and reattached. With same-station testing, there is only one connection to the DUT. Manufacturers can perform hi-pot and ground bond testing together without changing and reattaching test leads. This increases productivity and lessens the work involved with the setup and performance of electrical safety tests.”

Indeed, same-station electrical safety testing has advanced from complex systems consisting of multiple testers or big and bulky multi-function analyzers to smaller, more comprehensive, and easier-to-use electrical safety testers. Technology is now in place to allow a single automated instrument to perform a.c. hi-pot, d.c. hi-pot, insulation resistance, ground bond/ground continuity, functional run, and even line leakage tests, points out Mr. Davis of Associated Research. “These are the most common tests specified and are beneficial to manufacturers that are testing to multiple standards.

“In addition, companies that do not have large budgets can now have a single instrument that can do all safety tests that are required in both design and production stages,” Mr. Davis adds. “Design tests are far more comprehensive than production tests. Now manufacturers can meet those stringent design standards without purchasing multiple testers.”

Harvest Gold, Anyone?

While an appliance may leave the factory looking good, assuring that colors don’t fade and metals don’t corrode during the life of the appliance can be a challenge. This is especially true when several different materials are used. For instance, although coated metal is predominant in major appliances, appearance parts can include plastic through-door access ports and ice dispensers on refrigerators, or control panels or end plates on laundry appliances. Even if not in direct sunlight, white plastics in some situations can begin resembling the harvest gold appliance color from years ago.

“There are a couple of main drivers behind this potential problem,” says Allen Zielnik, director of Strategic Technical Sales at Atlas Material Testing Technology LLC (Chicago, IL, U.S.). “One is that as manufacturers drive down costs, they go to new plastic materials. They often substitute expecting identical performance, but they may get a wake up call because of a field failure due to color change. At the same time, resin companies are developing new materials and promoting them based on better processability and lower cost. But sometimes they are not adequately tested for color stability and permanence. And new colorants such as dye-based formulations, which offer the designer new creative flexibility, may not have the same color permanence of older pigment systems.”

Therefore, Mr. Zielnik believes that testing needs to be done not just because of color, but because of performance. “In one washer application, a manufacturer substituted a new nylon material for a water pump gear,” he offers. “It found that the chlorine in the water as well as surfactants in the detergent began to crack the gear. This was an unintended consequence brought on by lack of adequate environmental testing.”

Looking at corrosion, Harold Hilton, product specialist at Atlas, observes that with the growth of the global appliance industry, some appliances are finding their way into new locations and in a wide variety of conditions around the world. In addition, warehousing and transportation conditions can be extremely variable. To address corrosion, appliances are subjected to humidity, temperature extremes, and even salt-spray and pollution within testing cabinets.

“Corrosion testing of appliances used to be hit-or-miss due to outdated test methods in outdated equipment,” Mr. Hilton says. “Then engineers at one manufacturer heard about a test used in the automotive industry and realized that their products were exposed to many of the same environmental conditions. General Motors developed the test they used.”

For appliances, a part or assembly is exposed to alternating steps of dry and wet conditions. The impact of those changing conditions accelerates the effects of corrosion. An even more advanced test from the Society of Automotive Engineers has proved that 60 to 80 days of exposure in a test cabinet is equivalent to 3 to 4 years in the real world for automotive coatings.

“And the trend today is to speed up the process even more,” adds Mr. Hilton. “One way is to use greater temperature swings. Now some materials are tested in extremes of 90°C to -30°C, rather than 60°C to 24°C. With this kind of testing, even stainless steel testing cabinets will deteriorate after several years. The best cabinet construction for these extreme testing conditions is fiberglass with a gel coat.”

As testing equipment continues to evolve, look for further developments that assist appliance producers as they strive to produce better appliances more efficiently.