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Jim Wachtel



I recently worked with a customer asking for help with upgrading the performance of their feeding machine. The machine indexes material into another machine upon demand, using a simple I/O handshake to feed in material when the processing machine requests it. Their prior designs have used VFDs and even stepper motors. While these low-cost machines did the job, they were unable to keep up with the marketplace’s demand for ever higher accuracy and speed.

Our TECHTEAM felt that switching to a servo motor-based system was the logical choice for delivering the enhanced performance requirements because with a servo motor, users can achieve the rapid accelerations and decelerations they required. Additionally, the servo motor system allows for much faster feeding, which also quickens cycle times. Adding to each of these speed improvements, a servo motor allows for the precise feeding of an exact amount of material.

Because of their initial concerns about both the servo’s expected cost, and implementation complexity, they were reluctant to make the switch to servo motors, concerns our team was quickly able to put to rest.

Enter the Mitsubishi MR-JET high-performance, low-cost servo!

The MR-JET is the newest, and lowest cost member of Mitsubishi Electric’s extensive servo family, and yet it retains all the precision control for which Mitsubishi Electric is known.

But what about ease of implementation?

Our team chose to pair the MR-JET servo with Mitsubishi’s low-cost iQ-F PLC which accommodates all the feeder machine’s I/O and control logic requirements, and which is capable of controlling multiple servos using it’s integral Ethernet.

Because no Ethernet switch is required, we simply ran an Ethernet cable from the iQ-F directly to the MR-JET Servo drive. If needed, we could simply daisy chain the Ethernet to another Servo using the 2nd on-board Ethernet port. In this case however, we used the second Ethernet port to connect to a Mitsubishi GOT HMI.

Programming was very simple to setup using GX-WORKS3 which uses a simple drag and drop utility to add the servo to the program. Programming the motion in the PLC was as simple as dragging standard IEC-61131 function blocks into the ladder program.

So, just like that, our customer ended up with a low-cost, high-performance servo system that is simple to program, simple to troubleshoot, and easy to wire!

This is a sample of the PLC program using simple function blocks for an Incremental move to control the product feed:




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