AKG of America’s research and development center at its Mebane, North Carolina, facility hosted a grand opening in February that features a new water/glycol thermal shock test stand for product validation. Truck & Off-Highway Engineering attended the event at the supplier of high-performance coolers, heat exchangers and cooling systems to get a first-hand look at the new 32,000-ft2 (2973-m2) facility.
The high-capacity, water-glycol, thermal cycle test stand can test large heat exchangers. It tests up to six products simultaneously with a combined water and glycol flow of 250 gal (946 L) per minute at temperatures ranging from -20 to +120°C (-4 to +248°F). The test stand features minimum inlet pressure of 1 to 5 bar (14.5 to 72.5 psi), as well as automatic leak detection, test stop, and email notifications.
“We build heat exchangers: they’re subjected to pressure inside, and they’re subjected to heat differentials. Both ultimately, at some point in their product life, fail our radiators,” Matt Rankin, director of new product introduction for AKG explained at the opening. “What we want to learn is how to predict that life and also how to extend it through product development.”
Applications for AKG of America’s products include construction, mining, agricultural, forestry, specialty on-highway machinery, power generators, compressors, materials handling equipment, and buses.
Although interested in making this addition for some time, Rankin explained that the thermal shock test stand became a priority for the company in 2016. AKG R&D manager Steve Sydnor started framing the specifications of what the company wanted to accomplish. Sydnor told media at the event that he envisioned the design for some time: “It’s been in my head since 2010.”
“Everything on it is custom,” Rankin said. The one-off test stand was installed in December 2017 and validation testing began in January 2018.
Before the addition of the test stand in Mebane, the company relied on third-party services for this type of testing, as well as AKG’s R&D headquarters in Hofgeismar, Germany, which also offers sophisticated testing. “We utilized them, or if it made more sense to do the testing in the States then we used third party,” Sydnor told TOHE.
“Being able to test multiple samples gives us a way to be more cost effective by combining tests if they have similar parameters, but it also gives us the ability to test four samples (or products) so we can get better statistical results to present to our customers,” Rankin said.
“What is kind of unique about the test stand is the series of manifolds and valves that we custom-build in house,” Sydnor said. On a monitor stationed outside the test stand area, Sydnor showed media two radiators and two oil coolers from different customers being tested simultaneously. “Each of the coolers is seeing the same exact flow rate and the same exact temperature profile.”
Two separate tests were previously required for this scenario, he noted. A 10,000-cycle test might take 10-12 days. It would take almost a month to complete these two tests. Now, with the new thermal shock test stand, AKG looks to shorten the number of cycles and perform more testing simultaneously.
“When we had this tested and designed, I asked for it to be very powerful,” Sydnor said. The number of test cycles can be shortened to 1500 maybe 2000 cycles, he explained. “We have large coolers like this [that] come from construction or mining; it takes a lot of power and energy to fail those coolers, so it could be 2000 cycles easily. We should be able to test a lot more samples than typical testing, maybe in less time.”
The R&D center in Mebane also offers a new laboratory for dissection and analysis and strain and temperature gauge installation.
"We can apply strain gauges smaller than a postage stamp that we can apply to a product at a number of different places to study strains of the expansion or contraction of the metal in those sensitve places," Rankin explained. "These gauges allow AKG to measure the deflection and by knowing the properties of the aluminum the company can actually predict life failure using that information."
Installing the strain gauges is very detailed work, Rankin said. It can involve very delicate gauges and soldering wires that can be the diameter of a hair.
The company has plans to install a charge-air cooler thermal cycle test stand capable of testing heat exchangers with combined internal airflow of 26,460 lb (12,000 kg) per hour at 482°F (250°C).
Sydnor explained that AKG also uses the test stand in conjunction with some of its larger customers. The company instruments a customer's cooler (radiator or oil cooler) with strain gauges and thermocouples, collecting test data out in the field, in their machines.
“We are able to use [our customer’s field] data to correlate and design an equivalent test; then the results will allow us to make a life prediction. It is an extremely valuable tool for us,” he said.Continue reading »