Mitsubishi CNC | M70-M80 Series | Servo Motor Vibration and Noise Suppression

In this article, we describe how to reduce servo motor vibration or noise (reason is electrical resonance) for Mitsubishi CNC (M70-M80 series) controlled machines. 

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Introduction

In order to reduce motor noise and vibration, Mitsubishi’s M70/M700/M80 and M800 series controller can be adjusted in a very short time without any other equipment.

Attention!
It is useful to have your hand on the EMG – EMERGENCY STOP button so you stop immediately in case of excessive noise and vibrations that may occur during this adjustment.

How to?

  1. First, the original values of parameters #2205(SV05), #2233(SV33), #2238(SV38) and #2246(SV46) are noted.
  2. Then we enter SV05 =100, SV33 =0, SV38 =0, SV46 =0.

3. The axis is moved from beginning to end along the entire axis range.

4. If there is no vibration or noise, parameter value SV05 (# 2205) is entered as 150-200-250-300-350-400-450-500-550 respectively, and at each value entered the machine is moved again in full axis range and vibration/noise is observed.

For example, when SV05(# 2205) =100, and axis is moved in full range and there is no noise, SV05(# 2205) =150 is input, repeat movement and SV05 (# 2205) =200 if there is no noise.

Above process is repeated until noise-vibration-chatter occurs.

Attention!
SV05(#2205), can be set up to 600, please be careful.
There is no lock on this parameter to prevent more than 600 values to be entered.
If you enter about or more than 600, the motor may be damaged due to vibration-noise condition.

5. Press DIAGN and DRIVE MONITOR buttons to get below image. If SV05 (#2205) value becomes too high, excessive noise and vibration will occur. You can stop this by pressing EMG AFLT value is to be observed at this time.

After getting the above image, the value written in red marking gives you the approximate value that should not be entered to the parameter.

We find the value closest to this value in the frequency table (see page 6) and enter the value into parameter SV38(# 2238). In our example, value is 524 and the closest value to the figure is 529.

We will write 529 in SV38(# 2238) in this example.

After entering this value to SV38(# 2238), we remove the machine from the EMG state, check for noise and vibration by hand and listen.

After entering the value, do not be fooled by the noise cut, we will try to catch the vibration-noise points by moving it again as we did when setting the SV05.

After adjustment of SV38(# 2238), we repeat the axis movement (full stroke) to see if there is noise/vibration anywhere and we check the maximum number of AFLT frequency value at DRIVE MONITOR page.

As in our example, when moving the machine through full stroke, there was noise in some places and at this time the AFLT frequency value was at most 226.

Now that SV38(#2238) parameter is already set, We search parameter SV46(#2246).

In the same way, we find the value closest to above AFLT value in the frequency table. In our example, this value is 226 and we find the table’s closest value to 226, we will write 225 to SV46(#2246) in this example.

Move the machine again to check for noise/vibration. Do not take into account if there is very little noise, since parameter SV05(#2205) will be restored to its original state in the next step, this noise will disappear.

Then look at the servo-drive model used in your machine, find the default value of SV05(#2205) in  servo-drives manual and enter this value. If you do not have this manual, set SV05(#2205) back to the previous value before start of this adjustment.

6. Find 1-A SV33(#2233) value based on your previous adjustment of SV46(#2246)

SV33 (#2233) Setting

As you can see, our example is 4 and we enter 40 to SV33(#2233) as seen in the picture below. This value is generally 80, sometimes 40.

This completes the setting process.

Keep in Mind

  • This procedure is only available in M70/M700/M80 and M800 series and is applied to reduce motor noise.
  • Do not try to correct mechanical noise generated by your machine in this way.
  • Support from the technical service department of the dealer is needed for this adjustment.
  • It is the responsibility of the authorized person/institution to adjust any problem that may occur during this setting.
  • Do not forget that these settings have been made and set by the machine manufacturer.

Hint: A small app. for Iphone to identify frequency of vibrations – “Feedback Detector”
Similar one for android phones – “Audio Frequency Counter”. You can download both from Google Play Store or App Store.


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