Your machines can talk

Most of what I do is turning data into information.  Taking raw numbers and turning them into a meaningful story.  Sometimes, the story explains where a company needs to improve quality.  Other times, the story explains how a new product is doing in the marketplace.  Most of the time, the story is how a factory floor is performing.  In real time.  Accurately.  And without user intervention.  Amazing.

How is this possible?  By making your machines talk.  It’s surprisingly simple to get started.

Take a Teco SG2-20VR-D PLC (actually called a PLR by Teco, but we’ll use PLC).  The key to this PLC is the RS485 2-wire communication – MODBUS.  MODBUS is simply a way to ask the PLC for status.  You send the PLC a command that says “Give me the status of all your outputs”, and the PLC responds with “here is my status”.  You can do this every few seconds to get a real-time view of the PLC.  We’ve done this with Arduinos, Raspberry Pis, Teco PLCs, Mitsubishi PLCs, Siemens, etc…  There are many ways to skin this cat, but the goal is the same.  Have your machines talk to you.

For example, we recently hooked up a PLC to a machine that molds plastics.  After every cycle, there is a signal from the machine’s controller that says it completed a cycle.  We tap off this signal and send it to the PLC as an input.  On the PLC, there is a counter that keeps track of how many times a cycle has occurred.  We ping every 1 second to get the counter value.  If the value has changed from 126 to 127 (for example), we know it cycled up.  We record this in a database along with a timestamp.  By comparing to the last timestamp, we have an accurate measure for cycle time for that cycle.  We also know how long it’s been since this last cycle.  And we have extremely accurate historical information for how jobs, parts, molds, machines, etc… performed.

How is this helpful?  Say your standard for a given product is 45 seconds per cycle, but the machine is cycling at 62 seconds per cycle consistently.  This throws off a lot of planning and costing activities.  17 seconds is over 26% of the planned cycle time.  If you’re scheduling a shop, this makes things unpredictable and you seem to always be running behind schedule.  More importantly, say it’s been 90 minutes since the last good cycle.  You immediately know something isn’t right.  For example, we found that a specific material seems to always take longer than expected.  We discovered mold release was used on almost every cycle and wasn’t accounted for causing longer than expected cycle times.  This started a 5-why as to why mold release was being used.  After some investigation, we found the mold temperatures were too high causing issues with the material.  The temperatures were raised to fix a different issue with mold flow.  Lowering the temperatures and increasing the sprue size solved both issues.  This entire investigation doesn’t happen without great information.  And this results in a 20+% increase in productivity.  If you’re a shop owner, this is fantastic.

This doesn’t change the need to physically go and see what’s going on, but it does provide useful information to ensure people are focusing on solving issues in real-time.  You can prevent small problems from becoming big problems.  You can automate things like hour-by-hour charts so your people can focus more on the why than on the what.  Instead of “what was our last hour?”, it’s “why was our last hour under target?”.  And it’s becoming easier and easier to do.  If you want help in getting your machines to talk to you, give us a call.  702.683.6376.

PLC Hardware

About the author

Greg McFalls is a recognized leader in the field of custom software solutions in lean operations environments. MCFALLSTECH was started to help as many companies as possible be more competitive in this age of advanced technology.

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