Robot greasing is an important element in maintaining the overall efficiency of your secondary packaging equipment. Over time, grease breaks down from friction and subsequent heat until its viscosity levels are insufficient in effectively lubricating and protecting the internal mechanical components. To ensure that your robots run smoothly and withstand wear or damage to critical parts, we address the four most important aspects of an effective robot greasing program.
The greatest risk of not greasing often enough is causing damage to internal components. Bearings can lock, gear teeth can break and servos can be strained. Most critical is the risk of harm or failure to Rotate Vector (RV) reducers – critical gear sets that control motor rotation, speed and torque output. Reducer replacement can be upwards of $10k between part, shipping and labor costs, not to mention the loss in profits due to line downtime.
The recommended frequency for robot greasing varies by brand and model. As a general rule of thumb, leading robot manufacturer FANUC suggests greasing every 3 years or 11,000 hours of operation. However, this recommendation is only a guideline and is based on ideal operating conditions – meaning moderate production rates in a moderate climate. Customers who are operating in high-volume production facilities, or those that are particularly hot or cold, should consider replacing their robot lubricant more frequently – as often as once a year.
GREASE TYPE AND TOOLS
Before you begin, it is important to ensure you use the correct type of grease or oil, which is indicated in your robot manual. Robots are similar to vehicles – different models require slightly different variations of lubricant in order to maximize performance.
Greasing kits can be purchased directly from the robot manufacturer and usually include a can of the appropriate grease or oil type in the necessary quantity, along with a hand pump. Additional tools are not required, but custom hoses and fittings can make the job easier and less messy. At the very least, you should consider attaching a bag to each outlet to catch the old grease as it is excreted to make cleanup easier.
PORT IDENTIFICATION AND JOINT POSITIONING
Before beginning the greasing process, identify the port locations. There are typically (2) ports for each robot joint: an inlet where new grease is inserted and a corresponding outlet where grease is released. Joints are labeled on the physical robot as J1, J2, J3 and so on, but the inlet and out ports are not. Because the ports are capped with bolts that can easily be confused with other types of bolts on the unit, best practice is to refer to the robot manufacturer’s manual to ensure you don’t miss any locations.
Keep in mind that robot joints may need to be positioned in a particular orientation when greasing to ensure grease can flow in and out through the channel(s) properly. The proper degree of rotation is noted in the robot manufacturer’s manual for each stage of the greasing process.
FLUSH & FILL
Giving the robot what is known as a ‘grease bath’ involves pumping in fresh lubricant, which subsequently forces the existing/old grease from the cavity. If the robot has been idle for any length of time or if you’re in a particularly cool environment, power up and run the robot for a few minutes until the grease has warmed up and liquefied to a state where it can easily drain.
Begin by using a hand pump to inject grease into the first inlet. While expert technicians may utilize expensive automatic pumps, robot manufacturers highly discourage inexperienced users from utilizing them, as they can easily blow out seals if pressure is not carefully monitored and regulated. This risk of damaging seals is greatly reduced by using a hand pump (the operator will feel the resistance from the pressure as it builds), but it’s still best not to inject grease more frequently than every 1.5 seconds. Don’t be surprised if initial pumping takes some time – as much as 15 minutes – before the old grease starts to come out.
Keep pumping until the outflow of grease is no longer dark in color and matches the color of the new grease. You should examine the expelled lubricant for flecks of metal that would indicate damage or breaks to internal components.
Once the flush is complete, keep the inlet and outlet open and run the robot for a period of time before resuming normal operation. Because grease expands as it heats, the pressure will build inside the cavity and seals are susceptible to blowing if there is no exit available for release. Running the robot with the ports open ensures excess grease is expelled and air pockets naturally form before caps are secured back in place.
Please consult your robot manufacturer’s manual for model-specific information, along with step-by-step instructions on how to carry out lubrication tasks. Alternatively, Pearson offers greasing service as well as training as part of its preventative maintenance service. Please contact us at 509.838.6226 for further information.