The information contained in this site is experiential and for general interest only. The application and impact of methods, suggestions or instructions can vary based on a wide variety of factors. Accordingly, the information on this Site is provided with the understanding that the authors and publishers are not herein engaged in rendering original equipment manufacturer advice. While we have made every attempt to ensure that the information contained in this Site is correct, Balanceworx is not responsible for any errors or omissions, or for the results obtained from the use of this information. All information in this Site is provided "as is", and without warranty of any kind, express or implied, including, but not limited to warranties of performance, and fitness for a particular purpose. In no event will Balanceworx or its partners be liable for any decision made or action taken in reliance on the information in this Site or for any consequential, special or similar damages, even if advised of the possibility of such damages. |
Closed loop pneumatic board troubleshooting |
Always start at the output line of the pneumatic board with a calibrated pressure measuring device such as the digital pressure box from DHI or PV350 from fluke. The easiest connection point is to remove the line from the 3 way valve that toggles between vacuum and pressure.
The pneumatic boards are calibrated from the factory to put out 0 psi at 1vdc. The ideal look-up table would look like this
BWX offers Dual Channel Pneumatic board |
COMMAND |
IDEAL PRESSURE |
FEEDBACK |
|
A common failure is zero shift and can be detected if the unit puts out pressure with a input of 1vdc or less. If the 0 is shifting it is time to replace the unit since it can effect the lower end of the downforce on the pad conditioner. If you are interested in a drop in replacement that uses the table from above please contact us. One note is the black nobs should be turned off, these are used to command voltage to the board for offline testing. If the pneumatic board checks out fine on all 3 of the used channels then it is time |
0 |
0.000 |
0.000 |
1 |
0.000 |
0.000 |
2 |
1.666 |
1.666 |
3 |
3.333 |
3.333 |
4 |
5 |
5 |
5 |
6.666 |
6.666 |
6 |
8.333 |
8.333 |
7 |
10 |
10 |
8 |
11.66 |
11.66 |
9 |
13.333 |
13.333 |
10 |
15 |
15 |
to verify the rest of the system. The 1st slot channel 1 is for platen 3 and the second board channel 1 & 2 for the same respective platens.
Next, check for leaks. The next step is to connect the calibration box to the input to the pad conditioner head and see if the readings match the numbers directly out of the board. If they don’t match, then follow the next steps.
|
| |
Check to see if the lines are secure at all the fitting connections working your way backwards.
Verifiy that the none of the rotating pulley’s or shafts have cut or slice any part of the line.
Check to see if the 3-way valve has failed and requires replacement.
The valve has 2 common failure modes one being the diaphragm that actuates the valve which can be heard leaking with pressure to an activated valve.
The second and less common is internal leak of the valve.
Useful Info. Once you have verified that you a good pressure source to the pad conditioner head some other items can be checked to ensure optimal performance.
- Verify that any rotary fittings are replaced on a PM schedule.
- Check that the internal chambers are clear of grease by using a N2 pressure nozzle.
- Replace the bronze bushing and keyway on a PM schedule.
- Check the rotation bearings for corrosion or loss of grease. Contact us if you are looking for a custom drop in solution to extend the life of these bearings.
- A good way to prevent drift of the internal diaphragm when it is new is to pack them with grease and stage them for PM’s. The excess grease is remove during installation so it is only lightly coated. This allows the grease to penetrate the material and calibration is done at a stable state of the diaphragm.
- Have a training program in place so everyone knows how to use the calibration equipment for instance to zero and span a downforce meter. It is also a good idea to have calibrated weights of the downforce used in processing to verify the meter prior to actual calibration of the tool.
- If you are looking for a low maintenance robust meter please contact us to provide a custom solution for your type of holder to match the height of the conditioning apparatus.
|
