Unique accumulation, helium sniffer leak detection technology is employed.
Involve, Test & Control Inc. (ITC), a Shelby Township Michigan-based designer and builder of leak test systems recently designed and built a special dual fixture three-position shuttle transfer machine to leak test two different types of large plastic battery covers for the automotive battery packs used by one of the leading electric vehicle manufacturers.
The shuttle transfer machine is a weldment structure 20-ft. long and 7-ft wide. The two dual fixture platens are indexed in and out of the leak test station in the middle of the machine. When parts are being tested on one fixture, the parts on the other fixture are manually unloaded and then reloaded by the operator with new test parts. Acceptable parts are marked with a green ink spot. The shuttle fixtures moves back and forth by a servo- controlled bearing and rail linear transfer system. Cycle time is 75 seconds.
In operation, the battery covers are manually loaded with the bottom opening down onto a loading fixture where diamond and round position pins radially locate the part. When the cycle button is actuated the parts are automatically clamped, sealed, air leak tested for “gross” leakage, and transferred into the test station where an upper rectangular chamber is lowered over the part , enclosing it. The chamber has viewing panels and LED lighting to assist in any needed troubleshooting. The helium leak testing sequence begins by continuing to pressurize the part with helium. If rejected, the part remains pressurized, the chamber is vented and, if desired, raised and the operator uses a helium sniffer wand to located the leakage area.
The machine is PLC controlled and utilizes the ITC ViCATS-He (Visual Control and Test System for helium tracer gas leak testing) as a gross test controller, gas management tool and helium leak test controller, Fig. 2. This cost-effective helium leak test system is using the accumulation method, and provides fast cycle times with high repeatability and accuracy. The ViCATS-He is capable of “accumulation” or “hard vacuum” methods, has multi-part flexibility for use with several fixtures and easily integrates with the PLC for complex applications.
The accumulation method eliminates the need for vacuum pumps and the need for the robust requirements of the fixture. When using vacuum, it is necessary to eliminate as many items in the test chamber as possible, and utilize rigid stainless steel construction. Without the vacuum, cold rolled steel, aluminum and plastics can be used as well as accommodating some devices inside the test chamber. Some rough guidelines for determining when you can use the accumulation method are large leak rates and enough cycle time available for the “accumulation”. If your leak rate tolerance is too low, it may be impractical to wait for enough helium to accumulate to see a significant “signal” from the instrumentation. Also, if your cycle times are very fast, it may be necessary to use a hard vacuum, or a large enough vacuum pump that can get to vacuum very quickly providing only sensing time… not any accumulation time.
Involve Test and Control (ITC) was founded in 2000 and specializes in stand-alone test instrumentation, systems, and machines. In leak test applications, ITC systems can utilize mass flow, laminar flow, pressure decay, and other measurement methods. Integrated systems interface easily with various types of LVDT, laser, vision and other sensors providing “virtual condition” quality assurance to part testing.
For Further Editorial Information Contact:
Al Pike, VP and General Manager
Involve Test & Control Inc. (ITC)
50508 Central Industrial Drive
Shelby Township, MI 48315