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MPM AP25 Print Repeatability Problem

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We've got a problem with our AP25.. I just finished repairi... - Sep 22, 2006 by Daxman  

Will do. ... - Oct 03, 2006 by Chris  

#44100

MPM AP25 Print Repeatability Problem | 22 September, 2006

We've got a problem with our AP25.. I just finished repairing and calibrating this printer. We needed to replace the camera. After the cal. was done, the print accuracy was superb. However, it seems now, the consistency will not maintain itself. This has been an issue for quite a while now. One board is great, the other is .5mm to 1mm off. we end up having to scrape a lot of boards and re-print them. Does anyone have any ideas as to what the problem may be? At this point, all I've done is checked the air pressure and cleaned the platens.

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#44105

MPM AP25 Print Repeatability Problem | 22 September, 2006

What type of tooling are you using ? Dedicated or universal ?

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chris g

#44107

MPM AP25 Print Repeatability Problem | 22 September, 2006

Have you tried doing a short diagnostic test? That will check the repeatability and backlash of the axis. Did you use the C-tool when calibrating the camera?

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#44110

MPM AP25 Print Repeatability Problem | 22 September, 2006

We are using the Universal tooling..the one with the side plates. I'm not sure what the C-tool is. The machine did not come with much. I'm running the vision system test now..I've never done it before..but I'll let you know what happens with it. To calibrate the camera, I zeroed the offset values in the ap.cal file, then taught vision for a board and loaded it to the stencil. I adjusted the X and Y screws for the camera prism until the boards was loaded fairly close to the stencil. Lastly, I printed a board and "taught vision offsets" until the paste was aligned perfectly. Should I have done anything else? Thanks Guys

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#44112

MPM AP25 Print Repeatability Problem | 22 September, 2006

I ran the vision test...here is what I got.

Camera System: Completed Repeatability

VX mean = -3.177942 Standard Deviation = .000059 VY mean = -12.114077 Standard Deviation = .000065

Vision System: Completed Repeatability * X axis mean = -3.177700 Standard Deviation = .000246 Y axis mean = -12.114506 Standard Deviation = .000120

Backlash X axis mean = .000197 Standard Deviation = .000104 Y axis mean = .000174 Standard Deviation = .000078

Not sure if this is bad or good.

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#44115

MPM AP25 Print Repeatability Problem | 22 September, 2006

Dax, Just an FYI....we have had AP25's for years. I have never had to calibrate them. Also, I am not a MPM service guy but I would have to say that if your standard deviation numbers are coming up less than .001" you are doing ok there.

Sounds to me like you simply have something loose.

Just a word of trouble shooting advice......Don't over complicate it. Check the most simple things first..Loose screws...loose stencil...etc...etc...

Save the plasma arc accumulator calibrations for last

Good Luck !

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#44117

MPM AP25 Print Repeatability Problem | 22 September, 2006

I think Sr is right. Miss prints are prolly a result of your tooling moving the board after the camera looks at the fids. It also could be the camera itself hitting the board from warpped board or tooling raising the board up. It may be the camera if the camera is hanging too low. Run with the hood up (safety key)to verify.

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KEN

#44131

MPM AP25 Print Repeatability Problem | 24 September, 2006

One wood agree the offset you are seeing is enormous and probably PCB tooling related. However, if this is ruled out you should have the C-tool to verify your cube alignment. Who knows, maybe your cubes are loose?

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#44141

MPM AP25 Print Repeatability Problem | 25 September, 2006

Thanks for the posts guys, I'd like to mention a few things... In my opinion, the tooling does not get any better than this. The board is fairly small and quite stiff. There is no board warping. The tooling plates are tight and the vacuum really holds the board tightly. The PCB does not move easily. The clearance between the camera and the board is acceptable. We have another AP-25 and set up the same tooling on it and it prints perfectly. I'm not sure what you mean by the "C-tool", or "cubes". Maybe I've heard them referred to as something else. What does the C-tool do? and what are the cubes? also, After further testing, we only see the offset in the X axis. Thanks,

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SWAG

#44143

MPM AP25 Print Repeatability Problem | 25 September, 2006

Not sure if this will help at all but you might try doing a lighting histogram test/adjustment since you have a new camera. It could be that your lighting is very bright or too dim and the camera is confusing features next to your intended fiducials. If you haven't already and you want to do this, I can explain how.

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chris g

#44149

MPM AP25 Print Repeatability Problem | 25 September, 2006

Daxman,

The diagnostic results didn't look very pretty. Especially on the vision x standard deviation. Any time there is an asterisk, that is a bad thing. The failure number for all axis, excetp theta, is .0002. Could need more air flow to the x platen forcer. Maybe dirty cube, or bad focus, or improper force on grub screw on the x forcer. That is the spring loaded set screw by the roller. It is recommended you use a force guage to achieve a reading of 3.4kg (7.5 lb).

If you remove the camera cover, you will see 3 cubes. These must be aligned properly. That is where the c-tool comes in. It is a cal. jig. E-mail me if you don't have one. Maybe I can let you borrow mine. Also make sure forcer psi is about 70. Do you know how to do a histogram test? Keep us posted.

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#44150

MPM AP25 Print Repeatability Problem | 25 September, 2006

Dax.. Please post when you find the problem. I am very interested to see the outcome.

I still stand behind what I posted earlier. My opinion is that you are digging too deep. But...I do realize there are always exceptions....

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#44166

MPM AP25 Print Repeatability Problem | 26 September, 2006

Thanks Chris... I do not have the c-tool, but I did make some adjustments to the middle cube when I was calibrating it. Like I said in an earlier post, I cleared the vision offsets in the ap.cal file and adjusted the middle cube until the board alignment with the stencil was really close, then did the Teach Vision Offsets. I've never been trained on calibrations...so this was a guess. I figured this made sense. By what you are saying though...the cubes may not be aligned?? If you feel that we need to properly align the cubes..I would be most appreciative to borrow yours. we'll put it on our shipping account. I'll go check the air flow, force on grub screw, and focus. Also, I do not know how to do a histogram test. Send me an email if you'd like to talk about loaning your c-tool. Thanks,

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SWAG

#44167

MPM AP25 Print Repeatability Problem | 26 September, 2006

Histogram: Place standard tooling block in centernest. Jog camera over block. Jog z-axis to soft limit. Place a white card under camera. User mode to test. Turn board lamp on. From test menu, select histogram. With board lamp on and white under camera, select next. Next again. Remove card and place solid, dark black card on block. Press next, next. Under reports, click on histogram data. You should see white histogram bars and black bars inside of bands shown on graphic. If not, adjust GS4 pot. in pneumatics tray clockwise to move white bars toward right (CCW to move bars left). Repeat steps until white peaks are centered in green band on chart.

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#44215

MPM AP25 Print Repeatability Problem | 27 September, 2006

Hey Guys, I checked the histogram...it doesn't look good. I'm assuming the graph for the black bars has to be in the green on the left and the graph for the white card needs to be in the green on the right?? Anyways, I can't find a "GS4 pot" I looked everywhere in the pneumatics tray....bashed my head on a few things...can't find anything. I saw a few pots on the power supplies on either side of the Panasonic camera controller...but nothing that said GS4. Any clues on where the heck this thing is?

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SWAG

#44217

MPM AP25 Print Repeatability Problem | 27 September, 2006

Open the rear door that has the cooling fans on it. Look at the wiper blade regulator, look toward the front of the machine about 8" or so and to then left 3"or 4". There should be a lexan cover/box over the board that has this pot. on it. If still there, GS4 is a sticker on the base plate that this lexan covered board is mounted to. The pot. is about 3/4 the way up on the board, closer to the rear of the machine and it faces upstream (upstream if your machine is L to R). You'll have to remove the cover to adjust it. MpM procedure only mentions adjusting to center white bars to center of green. I do not know what needs to happen (if anything) if the black bars are not centered.

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#44241

MPM AP25 Print Repeatability Problem | 30 September, 2006

I found this pot, and tried adjusting it. It was already turned to its maximum, and the histogram did not look good. I tried replacing the board lamp and this helped the histogram a lot, but I am not able to get the bars centered in the green. The question is, which green band am I shooting for? the one on the right, or the one on the left? Also, on the cable tray for the VX axis (the one that has the flexible plastic cable wrap for the camera cables) I noticed that there is some kind of plastic that lines the underside of the metal plate. I assume this is some kind of skid surface for the cable harness? anyways, it was all cracked and my guess is that the cable harness was binding on the cracked edges. I replaced the smooth plastic and re-ran the vision test. It passed very nicely this time. However, we are still seeing some misaligned prints. When we purchased this machine, we did not receive any calibration or operation manuals. We just have a basic maintenance manual that doesn't explain a lot. Does anyone have copies available?

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Chris G.

#44255

MPM AP25 Print Repeatability Problem | 2 October, 2006

Daxman,

Did you get my e-mail? I'm feeling generous today, so I can fax you cal. proceedures and maybe loan you a c-tool. Let me know if you still need help.

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SWAG

#44257

MPM AP25 Print Repeatability Problem | 2 October, 2006

Daxman,

Try this: - it might help your histogram.

The camera may be operating production reads at or close to the z-axis drive limit but you don't know really. Write a dummy program that will allow you to load a PCB into the centernest at vision height - make sure thickness is correct. Place a white and black card on this PCB so that the histogram is performed at the correct, operation height. As for black being out, it will follow the white but not as drastic of movement. You don't have control over it. Try to get white centered in green area to the right of the graphic. The black might be messed up because you are not using official cal. cards which might have different reflectivity. You could try black tape although that might be a bit too shiny. You could also try paper that has dull black on it from photo-copying something solid black to avoid sheen problems. Make sure the white is very solid, non-translucent like a thick business card or something like that because this is what your adjustment is ultimately based on. Beyond this, your guess is a good as mine. Hope this helps.

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#44267

MPM AP25 Print Repeatability Problem | 2 October, 2006

ARGGH! I've verified proper airflow, made sure everything is tight and secure, cleaned and lubricated the bearings and nothing seems to help. first few boards are nice...then the next few are really bad..then they kinda get good again. I have no idea what is causing the drift. I'm sort of lost here...not much experience calibrating/troubleshooting these machines. Chris, I'd appreciate you're help, thank-you for offering. No I did not get your email. Try me at, meshuga@sasktel.net I can get you the fax numbers and other details from there. Thanks,

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#44304

MPM AP25 Print Repeatability Problem | 3 October, 2006

Will do.

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#44581

MPM AP25 Print Repeatability Problem | 17 October, 2006

Hey all, I just though I give you all a quick update. I managed to get the printer working. The problems were a combination of everything that was discussed here. When I adjusted the GS4 pot for the histogram, I turned the wrong one at first. This threw out the timing on the board and stencil light. (for some reason, both lights would not come on at the same time, but would come on individually) I corrected that problem and got the histogram test to pass. I used the C-tool to align the cubes, performed the "calibrate vision" After that was done, I printed a board and it was just slightly off. I used teach vision offsets to correct. We've run quite a few boards now and the repeatability is excellent. Thank-you to everyone who offered their help here. Much appreciated!

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