In mechanical engineering, backlash, sometimes called lash, play, or slop, refers to the clearance or lost motion in a mechanism caused by gaps between parts. It is the angle or distance a part of a mechanical system can move in one direction without moving the next part in the sequence.
Why is Backlash a Problem?
When gears are manufactured, it's impossible to make all gear teeth perfect. Designers intentionally make gears slightly undersized to prevent binding and ensure smooth operation. This clearance results in a brief moment where the output shaft remains stationary when the gearbox changes direction, causing an offset equal to the clearance. Backlash can also come from reducers, indexers, ball screws, and couplings, leading to positioning errors that can significantly impact machine performance.
Mitigating Backlash
- Load-Side Encoder: Attaching a load-side encoder to your application provides real-time feedback to the servo amplifier, allowing the motor to compensate for backlash based on the machine’s position. This solution, however, increases the cost and complexity of the machine.
- Built-In Backlash Compensation: Motion controllers often have a built-in backlash compensation function. This function allows the user to input the amount of backlash, and the controller offsets the motor's motion by this amount when changing direction. However, measuring backlash accurately can be challenging and requires special tooling.
Mitsubishi Electric’s Solution
Our MRJ 5 servo amplifiers feature a backlash estimation function. This function rotates the servo motor back and forth at four points along the machine’s travel. By measuring motor feedback, the amplifier approximates the machine’s backlash. This process is quick, taking about two minutes and a few clicks.
Steps to Use the Backlash Estimation Function:
- Power on the amplifier and connect it to your PC with a USB cable.
- Open MR Configurator 2 and switch to online mode.
- Under the Diagnosis tab, select Gear Failure Diagnosis to open the estimation function.
- Adjust the parameters to fit your application, write them to the drive, and cycle the power.
- Click Start. The drive will move, and in less than two minutes, it will show the estimated backlash.
Conclusion
Backlash is a necessary result of mechanical clearances but can cause significant positioning errors. The MRJ 5 servo amplifiers' built-in backlash estimation function allows for quick and easy estimation of backlash, enhancing your machine’s performance without the need for complex and costly solutions.
Thank you for reading, and I hope you found this information helpful. For more insights into automation solutions, stay tuned to our blog.
For More Information:
If you have any questions or are just looking for some help, we're happy to discuss your application with you. Reach out to us at (855) 737-4716 or fill out our online form.