February 6 2018
Your workhorse machine has given you decades of service due to your diligent maintenance practices and emphasis on safe and careful operation over the years. Overlooking one small and easily missed reminder can stop you dead in your tracks and result in costly downtime and service visits. This inexpensive component (usually less than $20.00) can save your organization a lot of grief if it is an included item in your preventive maintenance regimen.
Web handling systems and converting machines have used Programmable Logic Controllers (PLCs) for decades. Many of these legacy machines also have some form of operator control station that uses a small interface screen or Human Machine Interface (HMI). The programs for the PLCs and HMIs are usually developed by the original equipment manufacturer (OEM) and stored in the device’s memory. Very often a small back-up battery in the PLC and HMI retains this custom software and other critical register values when power is interrupted to the machine. As equipment gets older, these batteries get weaker and incapable of keeping the memory functional. Usually there is some form of reminder or indicator light to alert you once the battery power falls below a safe value. If these reminders are ignored and the battery dies, the program may get erased the next time power is removed from the machine. We have also seen numerous instances where the program remains intact, but critical register values are not accurately retained, and the machine does not operate properly. All it takes to prevent this is to be sure to pay attention to the low battery warnings and replace the back-up batteries when needed. The procedure is typically straight-forward but must be done properly and with power maintained to the device to prevent accidental program loss.
Staying on top of your back-up batteries’ replacement schedule can save you time and money. If you are not confident replacing the battery yourself or if you have any questions, it’s always best to contact the OEM to request assistance. They have the original programs and tuning parameters to restore the machine to factory settings should anything happen during the replacement or if you’ve already waited too long.
While you’re checking the back-up battery it’s probably a good time to check other items on your preventive maintenance list. In the follow-up article we’ll look at other items that should be high on your list.
