PLC Upgrade Unlocks Testing Efficiency

Oct. 1, 2014
For air filter manufacturer K&N Engineering, a high number of simultaneous parallel processes taxed an older test system. A controls upgrade for the test stations doubled test-process efficiency.

K&N Engineering ( manufactures washable performance air filters and air intake systems for a variety of systems, such as cars, trucks, motorcycles and industrial engines. The goal of this 45-year-old, Riverside, Calif., company is to design and manufacture air filters that provide maximum possible airflow while providing guaranteed engine protection. To do this, K&N Engineering tests all its air filters and intake systems at its laboratory facility, reaching cumulative filtration efficiency between 96 and 99 percent.

“We test our prototypes in-house to make sure all our criteria is met for our manufacturing facilities,” says Dan Chutes, IT manager. “After a filter is released to manufacturing, recurring performance audits are also done.”

K&N Engineering tests its products using the ISO 5011 testing protocol to assess filtration efficiency and dust capacity. The filtration-testing systems use a testing process that introduces many variables managed by multiple PID controller loops.

Robust control needed
“In addition to introducing a measured amount of specialized ‘test dust’ into the air filter, we also use a blower to create a pressure differential,” says Chutes. “Our system must calculate the correct airflow rates and volume in cubic feet per minute, as well as control the air stream pressure differentials.” Most importantly, the system must also monitor and control the pressure differentials across the filter element itself, in order to deliver accurate results.

“Beside multiple PID control loops, the testing process requires extensive math functions to compensate for varying environmental conditions,” Chutes says. “The high number of simultaneous parallel processes was taxing our older automation system, leading us to consider improving the system.”

Before the automation upgrade, three different computer systems were required to control the multiple calculations. K&N Engineering decided to upgrade to the more robust H2-DM1E PLC from AutomationDirect ( because “this PLC has a large memory capacity and a very high scan rate, which would accommodate our system’s advanced math functions and multiple PID loops.”

Features include a PID view and overview mode that allows for monitoring and tuning of individual PID loops or multiple loops, respectively. The H2 series CPU offers a total of 192 KB of memory, including 64 KB flash and 128 KB user data memory/SRAM with battery backup.

For the integration of this new PLC, K&N Engineering was familiar with its basic functions, in particular the programming software and the counter I/O modules, says Chutes. PC-based software is used to program this PLC, offering intuitive program window displays when a new program is needed or when an existing one is opened.

“We found the PLC’s modular design made it painless to add new functionality,” says Chutes. “We connected the PLC’s Direct Logic I/O modules that con- trol the servo motors via the variable-frequency drives (VFDs), facilitating very precise speed and position control of the testing machine when dispensing the dust.” The PLC’s onboard Ethernet I/O master expansion port can support up to 16 slave devices.

The ease of programming the serial communication to the electronic weigh systems was another added benefit, Chutes says. K&N Engineering also used the Ethernet connectivity to provide remote access from its PCs, which was impossible with the previous system.

With two test systems in the lab, K&N Engineering can now operate both systems at the same time using two 15-in. AutomationDirect C-more HMI operator interface terminals. Calibration and maintenance is now run on one test system, while testing can now be done on the other system due to more robust and streamlined control.

“Testing is also now a much more automated process,” Chutes says. “Now, an operator selects a part number and the specific ISO standard for the test, using the programmed, recipe-based functionality, and all the values are all retained in one CPU.”

The new system logs data collected during each test and is stored on a server. The data is easily accessible and presentable on operators’ screens in a variety of ways, such as flow charts and bar graphs. The data enables users to determine trends or spot possible problems a lot quicker than before.

“With increased automated testing effectiveness, data collection and ease of setup, the entire process is easily twice as efficient,” Chutes says.

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