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Feeder Communication

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#52694

Feeder Communication | 29 November, 2007

Hi,

I'm a final year student of Electronics Engineering and I'm gonna start my final year project about Pick and place system. I've seen the Siemens Siplace pick and place machine and wondering how does the tape feeder know when to feed forward the component? (whether the pickup device has picked up the component?)

and also how does the pickup device knows that the feeder is ready for pickup?

thanks in advance

Regards,

Henky

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#52702

Feeder Communication | 29 November, 2007

Some other machines are a lot simpler. Here's how the Philips (mady by Yamaha) CSM84 works. Smaller tape (8 and 12 mm) feeders are all mechanical. A plunger on the head pushes a lever on the feeder at the same time the head comes down. First, the feeder retracts a thin sliding plate that covers the top of the tape where the cover tape has already been peeled back. This exposes the pocket in the tape where the component is, allowing the nozzle to grab it. When the head is going back up, the plunger releases the feeder's lever, and a spring advances a ratchet pawl to turn the tape sprocket one notch of 4 mm. If the component requires a greater spacing, the plunger is commanded by the software to thump the lever up to 5 times to advance the tape the right amount. (This can get out of sync, and need manual pushes to get back in the right alignment with the tape pockets.) Larger tapes have pneumatic feeders, and the lever on the feeder opens an air valve to drive an air cylinder. This allows a much stronger spring, and the cylinders have stops with notches you set for 4,8,12,16, etc. mm of advance, to match the tape. With these, the software never needs to push the advance lever more than once.

The sliding cover I mentioned above lays right above the tape and prevents parts from bouncing out of the pockets, even when the feeder is turned upside down.

So, this is the most basic kind of feeder system, low cost, no motor, microprocessors, sensors, etc. in them, and it makes the head do most of the work.

Jon

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#52705

Feeder Communication | 29 November, 2007

Thanks Jon, indeed it sounds simple from your reply. But unfortunately I'm not a mechanical engineering student :( beside, my final year project is something about motors control and sensors. My supervisor suggest me to take a look at the feeder communication first because it seems to have some interface communication.

Henky

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#52718

Feeder Communication | 30 November, 2007

Sounds like Mydata might be one you could look at, for example. I don't have experience with them but they do have "smart" feeder capability.

Some machines use electronically controlled and motor driven feeders, some use pneumatic and/or mechanically driven feeders. In both cases, the machine knows a part is picked based on the vacuum level after the pick but the feeder doesn't know anything unless it's got input from the control system. It just advances when it's told to.

One type of motor driven feeder may advance whenever a nozzle breaks a photosensor beam at the pick location, unlike a mechanically driven feeder that just ratchets ahead when it gets punched. Our Philips has pneumatically driven feeders, our Quads use motor driven feeders. They both have there advantages and their liabilities.

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#52729

Feeder Communication | 30 November, 2007

This doesn't help the original poster any, but does the Quad have any sensing of what is going on in the feeder? On the pneumatic or mechanical Philips feeders, if the tape jams in the feeder for some reason, the head just keeps tapping the lever and never knows that the tape is not advancing, all it knows is it doesn't still have a component properly on the nozzle when it is at the placement point on the board. When the operator gets there to see what is wrong, you have no indication unless the tape has run out. If not the most obvious, you have to clear the error and watch closely to see if it is failing to pick up a component that is properly positioned in the feeder, or if the feeder is failing to bring a fresh component to the right spot for pickup. (Or, the more obscure, such as tape is binding just a little, so component is not centered under nozzle when it is picked up, then centering jaws knock part off nozzle when it raises, and then you get a low vacuum reject over the board.)

Having the feeder sense any of these problems within the feeder could be a real help. Sometimes the Philips feeders will continue to feed sluggishly, causing a LOT of dropped parts or just pick failures (like 50%) but the machine keeps trying to chug along as long as it doesn't get 4 pick failures in a row.

(I know the Philips CSM84 series is REALLY old-school today.)

Jon

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#52735

Feeder Communication | 1 December, 2007

"...but does the Quad have any sensing of what is going on in the feeder?"

Not with the feeders we use. Same deal as the Topaz, i.e., the machine knows if the nozzle has a part on it, but doesn't know what is happening in the feeder. There are "smart" IQ feeders available for Quad machines, but I don't know what capabilities they feature over and above the standard feeder.

You're right about the frustration of bad feeds with a Philips machine. It's the only real beef I have with ours, particularly with 16 and 24 mm feeders.

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