Customer SolutionsLabVIEW Simplifies Automation of Igniter Testing and Sorting
Author(s):Peter Blume, Bloomy Controls
Industry:Machines/Mechanics
Product:LabVIEW, PXI/CompactPCI
The Challenge:Increasing measurement reliability and reducing high labor costs of manual testing and sorting of hot surface igniters.
The Solution:Using LabVIEW to automate the testing and sorting of hot surface igniters in a dusty, high electromagnetic production environment.Saint-Gobain Igniter Products, a manufacturer of hot surface igniters commonly used for gas and diesel ignition, contracted Bloomy Controls, a National Instruments Select Integrator, to help create a new automated resistance test and sort machine. The company required a machine that provides accurate and repeatable resistance measurements; sorts multiple products that have distinct specifications within the same batch; reliably handles material; offers a user-friendly human-machine interface (HMI); performs at a high-volume throughput; and executes data analysis, data logging, and testing verification. Most importantly, the machine must perform reliably in a very dusty production environment that contains a large amount of electromagnetic interference. An igniter’s time to temperature represents the time required for an igniter to reach its designed ignition temperature after "turn-down" power - 15 percent less power for which the igniter is designed - is applied. In general, the shorter the time to temperature, the faster the igniter lights gas. Directly related to time to temperature is room temperature resistance (RTR), which is much simpler and faster to measure than time to temperature. The lower an igniter’s RTR, the larger the initial inrush current once power is applied, and the faster the igniter’s temperature increases and corresponding resistance decreases. The Saint-Gobain igniter manufacturing process includes RTR testing and inspection of the igniters. Previously, Saint-Gobain performed this function manually, giving rise to three primary problems - ergonomic issues, measurement reliability, and high labor costs. Automation offered a desirable solution to these problems. A National Instruments PCI-7344 4-axis controller card that resides in a PCI slot in a Windows PC controls motion. We used thirty-five digital I/Os for a variety of purposes, including safety interlocks, proximity switches, and optical sensors. A NI PCI-6527 48-bit digital I/O board that resides in another PCI slot inside the PC monitors a wide variety of digital signals. These signals include npn-type transistors (npn are open collector transistors with n-, p-, and n-type semiconductor materials for the emitter, base, and collector, respectively); contact closure (relays); and transistor-transistor logic (TTL) digital signals with 0-Volt level for nominal low logic and 5-Volt level for nominal high logic. To protect the system from noise spikes, we optically isolated all I/O. Most PLCs can connect to an external terminal or PC running HMI software. However, developing the HMI software typically involves techniques different from those used to program the PLC, which is normally accomplished using ladder logic. Also, while PLCs can perform motion control directly or by interfacing with an external motion controller, if performed directly, it requires substantial ladder logic programming. For example, a simple homing routine may require numerous lines of tedious ladder logic. If performed through an external motion controller, the routines may require fewer programming steps; however, we again must use a different development technique to program the motion controller than the PLC and HMI. Hence, three different programming languages could have been necessary to complete the application. Furthermore, all three languages would vary based on the choice of PLC make and model, motion controller, and HMI.
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