22 Signs That a Robotic Cell Has Problems
Posted on Mar 28, 2018 7:00 AM
How can you tell if your robotic cell has problems? These 22 warning signs will help you get your cell running at full capacity in no time.
Sparks fly, people shout, and warning lights flash. Plumes of black smoke spew from the machine, while workers rush to the nearest fire extinguisher. A deafening alarm blares throughout the workshop as the company lawyer calmly dials the number of the insurance company.
Sometimes it's obvious when a machine breaks down. Other times it isn't.
In fact, most of the time our machines don't break down completely. If they did, that would suggest a severe lack of proper maintenance. Instead, they just slowly stop working as effectively as they could.
The same is true with robots. Most of the time, it's not immediately obvious when a robotic cell has problems.
So how can you tell when your robot has encountered an issue? What we need is a list of warning signs – signs that we can watch out for to tell when a cell has problems. Well, here you go!
1. Piles of work-in-progress (WIP)
A robotic cell with problems quickly becomes a bottleneck. Often, the first sign of a problem is that WIP starts building up in the stages before the robotic cell.
2. Concerned team members
Employees on the shop floor are frequently the first to notice when a cell is not performing properly. For example, they may raise concerns that there's not enough (or too much) product coming into their own work station.
3. Low productivity
When there's an unexpected fall in overall productivity, you can be sure there's a problem somewhere in production. The robotic cell might be the cause of this problem, but you'll have to investigate further to be sure.
4. Product defects and reworking
Another warning sign is when an excessive number of products need to be reworked. As with the previous issue, this requires further investigation to establish the root of the problem.
5. An idle robot
A rather obvious sign that a robot has problems is when it sits doing nothing for long periods of time. However, it can take awhile for anyone to notice when a robot is idle, unless you use a monitoring software with automatic notifications.
6. Error messages
If you use monitoring software like Insights, it will notify you as soon as a robot is idle or encounters an error. You'll receive an email and/or SMS message telling you immediately that the robot has encountered a problem.
7. Emergency stop alerts
The first type of error alert you can receive from Insights is an Emergency Stop. This is usually triggered by an external input (such as a safety sensor or emergency stop button) and it leads to the robot's power being completely turned off.
8. Protective stop alerts
The second type of error alert you can receive from Insights is a Protective Stop. This also turns off the robot's power, but it is triggered by an internal trigger – usually a safety-related part of the robot's control system.
9. Safeguard stop alerts
The final error alert you can receive from Insights is a Safeguard Stop. This is similar to an Emergency Stop in that it's usually triggered by an external input (e.g. a safety sensor). However, it only pauses the robot, instead of powering it down completely.
10. Insights error flags
Along with your automatic notifications, you can view robot errors in the Insights software itself. These show up as red error flags on insights.robotiq.com, and you can also see how long the error was active before the robot was reset.
11. Low utilization
When a robot is sitting idle – either due to an error or lack of work – it's not being productive. This is reflected in the Utilization metric, which is one of the most important KPIs for collaborative robots.
12. Lots of unnecessary movements
The opposite of a robot that sits idle is a robot that moves too much. Your robot should move as efficiently as possible, or else it will waste both time and energy.
13. Low efficiency
Another important cobot metric is Efficiency. This indicates the amount of time that a robot is doing productive work when it's running a program. Low Efficiency suggests that the robot is waiting too long for other processes to finish, or is encountering errors too often.
14. Everything out of sync
Production relies on smooth communication between cells. When robots are involved, inter-cell communication is especially important. There are at least five signs that robotic cell communications have broken down, which you can read about in the article How to Ensure Your Cells Are Talking to Each Other.
15. Many long disconnections
The most obvious sign that a robot is having connection problems is when it disconnects from the network. If you're using Insights, such connection problems show up in the Disconnected metric, which will be high if a robot has connection issues.
16. Connection failures
Failed communication between a robotic cell and another machine can halt production completely. Such problems can show up in several ways, but a common sign is an error message on the robot's teach pendant.
17. Teach pendant error flags
Not all robot problems will show up on Insights, which is focused on productivity metrics. Fortunately, you can get a lot of low-level information from the robot teach pendant. The pendant will display errors regarding connection, programming, software, etc. This is especially helpful when debugging.
18. Software upgrade issues
As with any software, upgrades can cause problems. Whenever you install an upgrade to your robot, be especially vigilant in the hours and days afterwards so that you can react quickly to any problems that may arise.
19. Overheating motors
Although this is more of an issue with high-volume industrial robots, overheating motors can happen to any robot. A hot robot could indicate bad programming, a faulty motor, or another hardware issue.
Singularities occur when a robot tries to move to an impossible position. See our previous articles for more details: Why Singularities Can Ruin Your Day and Dealing with Singularities on Universal Robots.
21. Long wait times
Another important metric for collaborative robots is the Wait Time. This reflects how long a robot was waiting for external signals, such as for parts to arrive or other machines to finish. Excessively long wait times often indicate inefficiency.
22. Few cycles completed
Ultimately, the most important measure of a robotic cell's success is how many products it is able to process. On Insights, this is reflected in the Cycles Completed metric. If this number is unexpectedly low, it could indicate that the robot encountered some problems.
You can try out Insights for yourself within a matter of minutes by going to the Insights Demo at insights.robotiq.com. Try playing around with the interface and see if you can work out where the demo was experiencing some problems.