How often do robots need preventative maintenance?

Throughout the United States, we find robots performing dangerous and distasteful jobs that only present risk and boredom for human workers. Robots are used by various major industries, including Agriculture, Food Preparation, Healthcare, Manufacturing, Mining, and even by the Military.

Furthermore, we also have prominent examples of the automotive and the electronic appliances industries that use automation achieved through robots on assembly lines. Robots bring consistency in output, increase productivity, speed up the process, and deliver results closer to perfection.

According to a recent study by Tech Jury, there are 12 million robotic units worldwide as of 2020, with global spending on military robotics set to reach $16.5 billion in 2025. Through robotics, around 150,000 people have been employed worldwide as engineers and assembly workers.

Furthermore, 88% of businesses worldwide plan to adopt automation through robotics within their infrastructures, and from 2020 to 2022, a 12% increase in shipments of robots is expected worldwide.

Preventive Maintenance for Industrial Robots

Due to their ability to work continuously and supporting a tremendous amount of workload without any rest, robots include preventive maintenance to sustain their productivity and safety of use levels.

Without it, faults may arise, the robot might suffer from internal or external damages, and all of this may lead to severe losses and hazardous situations for businesses and organizations.

However, it is essential to know that different robots are recommended with varying amounts of time for preventive maintenance.

For example, the Japanese company FANUC recommends that planned preventive maintenance for industrial robots be performed for 12 months or 3,850 work hours, whichever comes first for your robot.

On the other hand, the German company KUKA recommends preventive maintenance after 10,000 hours of use for their robots. Hence, it is evident that a general rule of thumb isn’t possible, and therefore for many robots, the manual often offers the best time frame to carry out preventive maintenance for each robot.

Types Of Preventive Maintenance And Their Routine Cycle

There are several things involved in the preventive maintenance of robots. Some of the most common procedures are listed as follows:

1. Backing Up Controller Memory

Many motion control robots require their operators to understand the importance of backups and how they can prevent losing your robot mastering. If the backup is not maintained correctly, they could lead to unplanned downtime for robots in case of a service call, leading to a tremendous loss in productivity for any organization.

In backups, the most important values are the TCP (tool-center-point) positions based on zero points set for each robot joint. If these values are lost, then your robot may no longer work accurately. The best practice is to perform weekly robot backups as this will ensure the best and up-to-date values for the recent workload.

2. Checking for Defects

Industry 4.0 is the current trend of automation and data exchange in manufacturing technologies. It includes cyber-physical systems (robotics), the Internet of Things, and cloud computing as well.

In this new standard, several processes are linked together with the idea to perform an internal real-time feedback loop that offers a fast and precise diagnostic for correcting processes and issues.

The following figure showcases the Information Value Loop for Industry 4.0:

As you can see, cloud computing, IoT, and AI play an essential role in identifying processes’ accuracy and timeliness.

This means that when carrying out NDT (Non-Destructive Testing), these technologies can provide real-time detection of defects in robotics or deviations in their ability to produce results. However, while these technologies will require greater aptitude to prevent mishaps, the professionals at North Line Robot World recommend that you inspect robots for defects after every 3,850 hours.

3. Checking Over-Travel Limits

In motion control robots, the over-travel limits are categorized as either Positive or Negative. The Positive and Negative Travel Limits specify the position and boundaries in which a particular robot’s axis is allowed to operate.

When the Target Position exceeds the Positive Travel Limit, your robots are registering a Positive Over-Travel error. When the Target Position is less than the Negative Travel Limit, your robots register a Negative Over-Travel error.

Many of the present-day robots come with over-travel alarms as well as axis software limits. However, it is best that you periodically perform preventive maintenance every 12 months as it can help prolong your equipment’s life.

4. Checking Robot Repeatability

Robot repeatability is probably the most crucial factor which makes using robots efficacious in the first place. Repeatability is the ability of the robot to produce accurate results and deliver consistency in output.

This is why checking for robot repeatability and testing is a critical component for the robot reconditioning process. Many robots and their repeatability generally range from +/-0.02mm to +/-0.4mm. If the ranges are exceeded, then it means that your robot is not working correctly.

To test for robot repeatability, each robot is used for a minimum of eight hours. The data accumulated from this performance is then analyzed comprehensively to determine the source of derivations.

The ISO 9283 sets the critical criterion and method for accuracy and repeatability for industrial robots. A standard test is thus conducted over 24 hours, with a short test conducted over 5 hours.

5. Greasing Joints

Due to robots’ continuous and strenuous work, there can be signs of wear and tear, especially in the moving joints. This is why grease is applied to keep joints moving freely, smoothly, and in frictionless motion.

However, with time grease and oil products breakdown and thus lose their viscosity. Approximately after 500-700 hours, the grease in the robots will break down.

For those robots that are used daily, a monthly inspection for the color and consistency of grease is a must. Many robots use VIGO grease, a synthetic counterpart, and don’t breakdown quite as often as other greases available in the market.

For seldom-used robots greasing after a year or two can be harmful as by then, your robot would show a lot of wear and tear signs.

6. Inspecting Brake Operation

Robotic brakes offer precise control, which can hold robotic arms and joints accurately in place. Standard brake designs are most commonly used, while in some cases, even custom brakes can be developed to meet the special mounting needs and user-specific braking requirements.

In the case of medical-robotic applications, the ISO-13485 is applied. Common examples of brakes include spring-set brakes and permanent magnet brakes.

It is recommended that for both spring-engaged brakes and magnetic-engaged brakes, regular inspection is carried out. This can further be facilitated through the help of sensors built and installed for this specific purpose.

These sensors can then help you determine and detect the engagement and the disengagement of your robotic brakes.

7. Inspecting Teach Pendant

The teach pendant or the teach box is the control box for programming the motion of a robot. It can also be used to control the robot and perform a step-by-step iteration of the required process.

Teach pendants can be wired or wireless, and they are typically handheld devices. Mostly all teach pendants to offer you an error beep when an error is encountered.

These errors can further be viewed in the error log, which is automatically generated by the device. Teach pendants often support live-man switch and emergency stop features.

You can check these features using the teach pendant along with various other variables. You can do this at any time of the day.

8. Listening for Audible Noise and Excessive Vibrations

This is closer to visual inspection, where users of the robots can identify for audible noise and excessive vibrations in the equipment itself.

If such troubling events are identified, it is best to inform authorities and bring in an expert for closer and more detailed inspection to find out the cause behind the disturbance.

This kind of inspection is based on visual and other observational cues. It can have situational reasons behind them. You can inform your operators to be always on alert when they hear or find such discrepancies so that they can be readily dealt with without wasting time.

9. Monitoring Robot Motion

Robot control and monitoring systems tend to be complicated as they require a trained professional to use them.

However, many industrial robots are now coming with remote monitoring systems with IoT devices and sensors. In other cases, distributed systems for control and monitoring of robot motions are applied.

These systems can bridge the gap between programs written in different languages and carry out demanding tasks run on other platforms without the need to compete for processor time.

With these remote monitoring and distribution architecture solutions, authenticated users of robots can view and observe discrepancies in real-time and take adjusted measures to incorporate corrective remedies. Hence such preventive measures can be recorded and applied daily.

10. Testing Batteries

The secondary power sources of many robots are still batteries. Batteries are used to provide power for various elements such as installed software, system variables, and IO configurations.

Checking batteries ensures a free flow of work and fewer redundancies in operations such as downtime for changing or recharging batteries.

One quick look at the operative manual included with every robot that you purchase offers you the information you need about batteries.

Fresh batteries can be installed after the removal of the primary source of power. Hence, the removal and replacement of batteries in your robots depend on your battery’s model and make. However, it is also advisable to replace batteries after one year of use.

11. Tightening Loose Ends

This preventive maintenance can be achieved through built-in sensors and additional controls that warn users about loose ends in a robot. However, a visual inspection may take prominence as it is advised to check for loose ends before starting up the machine.

Conclusion

Working with robots in an assembly line or manufacturing plant requires your utmost knowledge and zeal to prevent mishaps and hazards from occurring.

As a trained professional, preventive maintenance and precautionary measures prioritize the safety of workers and the organization. I hope this post provided you with some valuable insights to conduct maintenance for your industrial robots. Please feel free to mention your query in the comment section below for any further questions relating to the topic.

About the author:

Amanda Jerelyn currently works as a Content Executive at Dissertation Assistance UK. She is fond of popular culture that references steampunk and mecha culture and their common variations in media. During her free time, she likes to read sci-fi novels, with the works of George Lucas, amongst her favorite.

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