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CP-642 specific part missing/inconsistent

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CP-642 specific part missing/inconsistent | 5 May, 2020

I am having an issue with our CP-642.

It will place fine a great deal of the time however when there is a feeder issue or if the cycle changes, after a part is replenished, it will suddenly miss RS1A diodes on the boards for about five to ten boards. The missing diodes are random but isolated to three positions. E.g. D12 is missing but D13 is not (right next to one another). Next board D12 is missing D13 is missing. Next board D42 and both D12, D13 are missing. There are 12 to be placed, I can watch and see that the diodes that get placed first are never missing, but the ones more towards the bottom right of the board are the culprits.

They are seen in the vision camera and accepted as good to place.

I have cleaned the clutches with IPA and replaced all the filters in the heads.

I cleaned and lubricated the feeder initially and that seemed to help but now it happens as stated above, after a nozzle skip, part out, or unrelated feeder issue.

I HAVE witnessed the diodes flying off when the turret rotates (once or twice, it is not consistent, so it is hard to catch).

In the program the nozzle is set for Minimum Dia. 1.90 and Maximum Dia. 2.70

I have changed out all the 2.0 nozzles

Any help would be greatly appreciated, perhaps there is something I am overlooking.

Thank you,

Robert Husted

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CP-642 specific part missing/inconsistent | 5 May, 2020

Check for nozzles that are stuck up. They may be able to pick the part but will drop the part during placement. I have also seen a feeder several positions over from the part not being picked/placed have a piece of carrier tape sticking up and not going into the cutter. In rare cases it will pick the part in question but get dislodged as the tape sticking up will brush the part off the nozzle. Also when something odd like this happens I have edited the insert order to place a part first or last or move the feeder to a different device location to see if that has any impact on the issue.

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CP-642 specific part missing/inconsistent | 5 May, 2020

Did you try changing spring on the feeder? Maybe you need board supports?

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CP-642 specific part missing/inconsistent | 5 May, 2020

I will have to check the nozzles to see if they are stuck up, but I don't believe so as I changed them all out a couple weeks ago.

I have not went back to the feeder yet because I am not getting vision errors. I was able to see the diodes fly off on the board side of the machine (around station 10), so the parts are making it past vision. The bottom of the machine, under the x,y table, is littered with said diode.

Is there a way to see which nozzle on which head was picking a particular part at a specific time?

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CP-642 specific part missing/inconsistent | 6 May, 2020

I thought i posted this last night.

The easiest way I can think of to see what nozzle is being used is to put the machine in step mode and do one part at a time.

Also the levelness of the table and Z0 could be suspect. On a CP643 this can get out of spec if someone gets support tooling stuck under the rail when the table tries to raise. I don't have any experience on a CP642 so I'm not sure if its the same.

I would check the programmed component height and see if someone programmed in a positive Z place offset as well.

Does it look like the paste was disturbed like the part was placed but it came back up with the nozzle? If so check to make sure the vacuum valve is getting turned off correctly and that your air blow off is working.

Slow down the placement. Sometimes the problem goes away or you can see what is causing the problem at a slower speed.

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CP-642 specific part missing/inconsistent | 7 May, 2020

Yeah my post disappeared as well?

I checked to see if there was an offset and there was not.

I tried step mode and all was good.

I DID get to capture one video in, slow motion, and it shows the part being placed, the nozzle rising, and then when the table moves the diode starts rolling around on the board. There are no impressions in the paste. I am really leaning towards a leveling issue now.

I don't understand why it would be so inconsistent if levelness is the issue? And what really stumps me is why it will run great until a unrelated part is out or there is a feeder issue, perhaps it is just coincidence?

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CP-642 specific part missing/inconsistent | 7 May, 2020

From what you described of what you seeing from the slow motion is that the part is not actually "placed"; it's more like drops on top of the paste, so it's floating on top only which vibrations would cause it to slips away.

Even though I am not familiar with Fuji machines, but I am sure there is something you can edit on the package data to slightly increase the "downward" place force for the nozzle to place the part seat into the paste.

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CP-642 specific part missing/inconsistent | 7 May, 2020

Being new to the industry, the question is how much squish should I see once the part is pushed into the paste? Is there a recommended offset to create the perfect impression in the paste?

I did notice yesterday that the height called out in the program is different from that which I measured with calipers, however 12 diodes are placed and I seem to only have issues with 3 of them. Two of the three are close to one another but the other is in a separate group and it seems to be the culprit of that group.

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CP-642 specific part missing/inconsistent | 8 May, 2020

The squish is determined by the spring in the nozzle.

If Z0 or table level is out, you would see it on more than one component..most likely

Make sure board thickness and component height are correct.

Also make sure you have board support installed if needed.

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CP-642 specific part missing/inconsistent | 19 May, 2020

Thank you all that contributed to the troubleshooting!

I measured the height of 10+ parts with calipers and found the average to be around 2.15mm. In the program height was set to 2.42mm. I reduced the height to 2.15mm.

I have since ran 561 boards and not a single one is missing any diodes. There are less failures overall. I am very happy with the results and THANK YOU again for your suggestions!

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