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Quality manufacturing demands flexible, scalable data acquisition tools

May 2013

The automotive industry has become a volume consumer of a wide variety of sensors in its quest to provide vehicles that meet both evolving customer-driven performance and operational requirements and increasingly stringent environmental guidelines. Over the past 100 years, automobiles have evolved from true horseless carriages with no instrumentation of any kind to the basic speedometer, gas gauge, ammeter, radiator temperature gauge cluster-equipped vehicle of the 40s and 50s to fully functional electronic device-laden transportation marvels available to the modern driver. All of the basic gauges - even in the days before pollution control - required some sort of sensor to provide input for the dashboard readouts. Be they mechanical - not too many of those are left except for the speedometer cable - analog, or digital, the evolution of these sensing systems have marked automotive progress into the 21st century.

Variety is key

Modern automobiles rely on an untold number of sensors to provide operational information to the driver, monitor and optimize engine performance characteristics, drive train, and handling characteristics, monitor and control emission, optimize fuel economy, warn of potential mechanical or electrical problems, and optimize passenger comfort. Hi-Stat Manufacturing of Sarasota, FL, a division of Stoneridge Corp. (Warren, OH) is a volume supplier of a wide variety of sensors to the automotive industry. Companies that purchase Hi-Stat's products for their vehicles include General Motors, Ford, Chrysler Corp., Nissan. Volvo, and Range Rover, both domestically and abroad. According to Scott Yancey, reliability and development lab manager, at the Sarasota location, Hi-Stat produces and ships 50 different sensor types at a rate of 250,000 items per week to their customers.

"The variety of sensors manufactured at this location varies with requirements of our customers," says Yancey, "but within our catalog of sensors we include four basic types. These include fluid level sensors, temperature sensors, pressure sensors, and magnetic-based speed sensors. Packaging of these units can vary greatly but, for the most part, falls between the size of my little finger and a 1½-in. diameter by 6-in. long cylinder. The largest sensor we produce weighs slightly more than 2 oz."

Production at the 125,000 sq. ft. Hi-Stat plant is highly automated with 100 % production level testing carried out on all sensors manufactured. "Our lab facility is rather large," Yancey adds, "but its 4,400 sq. ft. is an absolute requirement to providing room for the extensive test programs we are often called on to perform. The lab does both routine parametric testing of products under controlled environmental conditions as well as troubleshooting off-spec product in order to identify and correct production problems. We have a lot of specialized environmental chambers, all of which are required to accurately test product under real-world conditions. Not only can we cycle and test product thermally from -40 to 150°C but we can subject our sensors to other potentially hostile field conditions including humidity, vibration, and accelerated corrosion. In order to do this efficiently and economically, the lab needed an upgrade in its data acquisition equipment."

Enter the new project 'dragon'

As any test facility manager is likely to tell you, nothing makes looking for the upgrade you "thought" you needed a priority quicker than a the arrival of a new and demanding customer-based testing program. "In our case it was a 2004 Model Year vehicle program, a highly publicized replacement for an already high volume vehicle model. The customer required that the sensors that were mounted on both the front and rear wheels as part of the stability and anti-lock brake systems of this entirely new vehicle be tested 96 units at a time in parallel. The test required monitoring of all 192 sensors in one minute intervals for a 7-week period. In short," Yancey says, "the lab's existing data acquisition equipment was not up to the job."

Scott Yancey chose to upgrade his test capabilities using the new Fluke Corp. (Everett, WA) LAN-enabled 2680A data acquisition system. According to Yancey, the 2680A provided the flexibility and scalability to handle this demanding new project. The Fluke 2680A features a 120-channel capable design, is flexible and scalable to 2000 universal channels per system, features an optional OPC server that is said to allow easy integration with existing software, and eliminated need for external signal conditioning - a potential savings of up to $250 per channel.

"I knew adding the 2680A would provide the lab with the needed capacity and scalability for the new project with Ford. However, it was the flexibility of the system and the adaptability of the Fluke's latest revision of their proprietary software, Trendlink, which has allowed the lab to do so much more. We can now more easily handle the wide variety of system setups that the lab encounters in our diverse testing programs. The new software allows me to provide our customers with extensive real-time data from any number of sensors over interval in a given test period. The data can be used to verify performance or provide valuable insight into parameter variability or trending in the case of production problems. In either case, all data can be captured and sent to interested parties electronically as required. Being able to do this for our customers has been just great, they really like this capability."

It's a digital world out there

Like most of the electronics world, sensors have gone increasingly to digital output. Hi-Stat's production has done the same. "The percent of our sensors that provide digital output has steadily risen. Approximately 75 % now are in that category. "The fact that the 2680A does not require external signal conditioning really works for us." Yancey says, "This feature has come to represent significant savings in our testing programs."

The Fluke 2680A data acquisition system chassis is designed for small to large multi-channel applications requiring reliable Ethernet communications. The front-end chassis system style has six-slots that allow users to custom build a complete data-logging system. Five of the slots accommodate any combination of 20-channel universal input modules compatible to the new 2680 Series, effectively doing away with the need for, and the added expense of, external conditioning. The sixth slot may be used for an additional analog input module or for an available digital I/O relay module that adds an additional element of control to the system. The 2680A's 10 BaseT and 100 BaseT compatibility means it will communicate with older networks as well as newer 100 BaseT installations.

Additionally, using Ethernet TCP/IP protocols and network interfaces for 10/100 BaseT, each analog modules features a proprietary Universal Input Module that lets users connect and measure virtually any electrical parameter without requiring external signal conditioning. Available 20-channel measurement modules include a fast analog module offering1000 readings/sec and a precision analog input module with up to 300 V channel-to-channel isolation. Inputs compatible with these units are V dc, V ac, resistance, current, 4-wire ohms, RTD, thermocouple, thermistor, frequency, and totalizer inputs. Compatible outputs include digital I/O and alarm relay contacts.

Quality pays off

According to Scott Yancey, use of the new Fluke 2680A data acquisition system has gone a long way to help the reliability and development lab to control what could have become spiraling costs associated with more demanding projects. Yancey is quick to report that use of the 2680A system to support the wide variety of tests that his facility must perform has met his expectations.

Yancey says, "Costs of testing has decreased with integration of the new 2680A unit. A 50 % reduction in recording time has increased our lab capacity greatly. Because of the unit's versatility and ease of setup, the technicians are now free to run other customers' programs in parallel - greatly increasing throughput. I estimate that the lab is now saving $6700 per validation test over previous setups with older equipment. Labor costs are also down. In short, even though 90 % of all products coming through this facility are monitored, we have been able to sustain our customer requirements - something that they have come to expect from Hi-Stat Manufacturing. And because we are QS-9000 and ISO-9001 certified, they count on it."