Author Topic: Pick and place build, openpnp  (Read 1389 times)

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Offline mendez

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Re: Pick and place build, openpnp
« Reply #25 on: October 04, 2019, 12:15:17 am »
@pisoiu

That looks nice!! Keep up the good work!
 

Offline pisoiu

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Re: Pick and place build, openpnp
« Reply #26 on: October 05, 2019, 08:01:19 am »
And we have X axis:

 

Offline stoyanoff

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Re: Pick and place build, openpnp
« Reply #27 on: October 06, 2019, 05:31:12 pm »
Impressive! Congrats!
The hardware is serios! I`ll show you mein in a few days, when I`m ready with the control. But I don`t use  cartrige guides and lead screws, but rods and belts! I think your approach is better. I think I will have problems with the vibrations, but I am not sure. Your design is 100% better!
Best regards!
 

Offline Kjelt

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Re: Pick and place build, openpnp
« Reply #28 on: October 06, 2019, 05:40:01 pm »
I like the 45o tilt on the Y axis, you don't see that that much.
I only saw it on an assembleon machine once.
You like to share you're thoughts why you choose this over the standard 90o approach  :popcorn:
 

Offline SimonD

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Re: Pick and place build, openpnp
« Reply #29 on: October 07, 2019, 06:27:57 am »
Hi,
Very impressive plan! Can I ask how much money it has cost so far?
Thanks.
 

Offline pisoiu

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Re: Pick and place build, openpnp
« Reply #30 on: October 07, 2019, 08:39:04 am »
Stoyanoff,
My design may be better in regard to some aspects but is definitely worse on others, in which your design is better. As everything in life, there are pros and cons in each choice. My design is better in precision and speed than a stepper and belt design, but is much more expensive, difficult to calibrate and heavier.

Kjelt,
This approach is a result of a combination of factors. My table has roughly 1x1.5 meters in size, it is very big, table alone have around 90-100kg. This is due the particularities I need for my machine. This whole pnp business, as I see it, is focused towards high speed in medium and high production volumes. This is why we see components on feeders and those are the kind of machines designed and optimized by big players in industry. But this is not good for low volume and prototyping, and everyone who asked quotations from PCBA for 10 pcs, knows it. This is also my business, designing many different products, prototyping them in 5-10 pcs and then low production batches, up 1000 pcs. For me is critical to have a fast machine setup and possible offline setup. I cannot spend an entire day setting up a machine for 100 unique components then run the machine for 10 minutes to produce a test batch. I need that machine offline and loaded up in less than 30 minutes. Fastest I can think of is with cut tapes and some kind of standard fixtures. Not feeders. Maybe only on very common components like 100nf and that feeder stays on the machine. Cut tapes are most common when we are talking about prototyping, it is not economically feasible to buy full reels or pay re-reeling service only for 10-20 components. This is why I need big XY space, for many cut tapes and trays.
And that comes to your question about 45 degrees. That 1.5 meters X support has to be very solid to avoid deflection. The profile has 2 stainless steels bars inserted on sides. The carriage balls run on those bars when traveling. If I would placed the profile horizontally, it deflects in the middle with approx. 0.2-0.3mm only due to its own weight, not counting the head weight. If I would place it vertically, it bends and it induces oscillations when travelling on Y axis, because it is quite flexible in the direction of travel. That is why I placed it at 45 degrees, to obtain stiffness in both directions. The only other way was to use another profile type, square, but that one would have been much heavier, and this is not good for Y drive elements, supports and performance.

SimonD,
I do not have at this moment total costs, they will be accounted only at the project end. But I can give you some price examples for most important components:
-ballscrews (plus end supports and motor connector) are TBI, around $750 plus $250 shipping from China
-Panasonic minas a6 400w servos, drivers and cables for both axis, around $1000, also from China. From european distributor, one motor alone was quoted at 700 eur.
-precision aluminium table 1x1.5 meters plus raw aluminium material for manufacturing parts: $800
Then comes the interesting part of fitting all together. If you do not have a mechanical workshop at your fingertips and you don't know how to use it, prepare to spend a lot in designing and manufacturing unique mechanical parts. This is also valid for every other task which you have to put others to do it if you don't know how to do it yourself. Calibrating mechanics, configuring servos, vibration analysis, driver hardware and firmware design, optical systems design, pneumatics, integration with software, etc....
« Last Edit: October 07, 2019, 10:05:05 am by pisoiu »
 

Offline MR

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Re: Pick and place build, openpnp
« Reply #31 on: October 07, 2019, 10:15:39 am »
Seriously I think you underestimate a Belt design, my Mechatronika is very precise with a belt (in theory hah since those id**ts misconfigured the servo motors initially and we had to fix it by ourself), but they also do a reduction (can't say how much they do on the Y axis since I did not pay too much attention to it, it should be at least >2:1).
Even if you watch some high speed Siemens pick and place machines, they're also using belts. I think the idea that belts aren't accurate enough comes from inexperience.

Belt design (older Siemens, but I'm sure even that would be high level for openPNP at the current stage):





this is a stepper based system

From my point of view the only intelligent part of a pick and place machine lies in the pick and place head nowadays. The X/Y movement is nothing worth to mention anymore.



-> my opinion the X/Y movement is the easiest part of that machine.... pay attention how close the camera is, the illumination of the PCB is crucial, my Mechatronika is an utter failure with that (you can see the big distance of the camera and illumination ring in the first video) and misdetected fiducials can end up in misplaced or shifted components - and a lot re-working.



-> this one picking up all components at the same time, you might need adjustable feeders for that
I would say this is even more efficient than gatling gun pick and place heads I would say, in those areas feeders are the key point.

https://www.youtube.com/watch?v=JQcf46hquNQ&feature=youtu.be&t=21

this one needs special feeders .. it's getting expensive. some of them don't even use the regular stripe feeder anymore but just queue up the components in a slot.
I wonder if that guy also talks like that with his wife at home, freaky ad-talker.
« Last Edit: October 07, 2019, 10:21:36 am by MR »
 

Offline pisoiu

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Re: Pick and place build, openpnp
« Reply #32 on: October 07, 2019, 11:00:16 am »
I do not have practical experience with belts on pnp, so yes, I may have some misconceptions. But what I see is that many manufacturers move from belt to ballscrew. In my unexperienced opinion, the accuracy of a belt design has not much to do with the belt itself being imprecise by construction, rather with the fact the material has some elasticity and that creates oscillations when using short acceleration and stopping times. Of course, that can be mitigated by proper servo tuning, using of external encoders, etc. but before being mitigated, designer must have means to analyze them and that can be done only with accelerometer based instrumentation or with high speed camera. Manufacturers, perhaps, have such tools. DYI builders most probably don't.
I have some experience in the past with transmissions with belt in other systems and I found them difficult to purchase and the variety was not as wide as ballscrew's. Also, the design of the drive/support ends is a bit more complicated for me, compared with ballscrew, which has all components readily available, aliexpress/alibaba is full of suppliers.
Otherwise yes, XY movement is the least challenging part, I expect to be a little difficult only at servo configuration and tuning.
Vision system will be with coaxial illumination, ethernet camera on head and usb camera on bottom. I have already built and tested a rough prototype. Currently, openpnp cannot work with multiple component cameras, so for the moment I'm stuck with one. In the future, I plan to develop a fly vision camera to speed up things.


LE: your M80 have one nozzle travelling over...don't know exactly, say 50cm from the videos? Mine will have 24 nozzles (hopefully) over 150cm. I would need a pretty wide belt :)
« Last Edit: October 07, 2019, 11:29:50 am by pisoiu »
 

Online SMTech

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Re: Pick and place build, openpnp
« Reply #33 on: October 07, 2019, 11:32:41 am »
Most bigger machines stopped using belt a while ago, these days cheaper machines use ball-screw and more expensive ones use linear motors. Linear motor options are often promoted as a zero maintenance option.

On our Essemtec it is suggested the 30mm X belt is changed every ~2 years (but this will depend on usage, 5+ seems more common as far as I can tell) on a Paraquda at least Y is driven by belts on both Axes and these last 10+years, although again Essemtec would like you to change them more regularly. When the belt fails you will hear the gantry vibrate when it moves, all the belts can be tensioned & the tension is checked by measuring the resonant frequency by plucking it. On these machines there are linear encoders on both Y axes as well as X, the location from all of these is fed back to the servo controller. A full calibration of the machine maps the location of a glass plate covered in fiducials against the encoder data.
 

Offline Kjelt

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Re: Pick and place build, openpnp
« Reply #34 on: October 07, 2019, 12:51:32 pm »
AFAIK belts can be equally precise as ballscrews but they have some disadvantages, the tension is falling after time so you need auto tension mechanisms and they wear out much quicker than ballscrews.

Also with ballscrews you need to weigh speed vs accuracy, they are available in 3mm travel per rotation upto over 20mm travel per rotation. If your servos or closed loop steppers are accurate enough it does not matter and you often see the larger travel per rotation ballscrews used in p&p machines to optimize for travel speed.

Linear motors are the ultimate but very expensive and quite dangerous if you are doing the pid control loop on your own.
 

Offline MR

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Re: Pick and place build, openpnp
« Reply #35 on: October 07, 2019, 01:23:24 pm »
Linear motors are the ultimate but very expensive and quite dangerous if you are doing the pid control loop on your own.

After my experience with the Mechatronika machine (which is using Delta Servo Motors) I can say that those motors are pretty easy. There's almost nothing you can do wrong if you're careful enough.
A completely misconfigured PID will result in a controller shutdown of the motor.
So you just need to take care that you won't run against the boundaries of the machine.

The other question:
The mx80 has a travel distance of around 50cm.

After all my experience with the machine I can say all Mechatronika really sells is the machine (at a cost which just does not justify anything they sell) ... but for a successful manufacturing ability you'll need much more...

a) stencil mask printer, and experience with solder paste
b) component management
c) maybe AOI, depending on what you want to do

The big limitations of our machine:
- I need a tray feeder, we're currently juggling trays manually it's okay but I don't like that. There's a commercial company (probably the first one you'll find on youtube) which sells one tray feeder for 20.000 EUR (yes right, 20.000 EUR). I'm not going for that, I'd rather do it myself with a few steppers and a 3d printer for prototyping.


If you would have done a portal design with the portal being longer than the Y rails you could pick the components from outside of the portal.

See:


That's all stuff you learn once you juggle with feeders :-) Yamaha CL Feeders seem to be okay (I'm just starting with it and building an adapter for my mechatronika mx80).

One problem you definitely cannot have is parts falling into the machine, the Mechatronika MX80 is braindead when it comes to that, you cannot get things out of the machine without special tools. We have already modified the machine so we can get inside it.
 

Online SMTech

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Re: Pick and place build, openpnp
« Reply #36 on: October 07, 2019, 01:56:18 pm »
Trays represent a major issue to anyone who has multiple ICs that come packaged in trays on a single design. Its true for pretty much any vendor. Typically there is a basic option that uses up around 30 feeder slots and hold two trays, sometimes there might be an intermediate option where a feeder cassette that uses fewer slots can be loaded and it can alternate between ~6 trays, this is an option I've seen on Dima for a reasonable price & I think Fuji do it too, some devices in trays can be quite light so the mechanism needs to be smooth so nothing jumps out of its pocket. The next option is your more typical filing cabinet sized tray changer, £20k is a pretty good ballpark price I think, these can hold lots of trays so you are covered both from a volume and multiple device type perspective.

Two machines take a different approach, Europlacer have the option to fit a tray inside the machine over the conveyor that holds 10 trays and Hanwha have a tray feeder that feeds from beside the machine so uses no feeder slots. I think some Yamaha/iPulse machines have(or the option to) a tray area inside the machine possibly at a cost to max PCBwidth.
 

Offline Kjelt

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Re: Pick and place build, openpnp
« Reply #37 on: October 07, 2019, 02:10:47 pm »

Linear motors are the ultimate but very expensive and quite dangerous if you are doing the pid control loop on your own.

After my experience with the Mechatronika machine (which is using Delta Servo Motors) I can say that those motors are pretty easy. There's almost nothing you can do wrong if you're careful enough.
I was talking about LINEAR motors.
Those do not have any physical resistance (like a ballscrew or belt) which can slow rhem down, they can easily do 20G acceleration.
I have seen the damage it could do , a 1m linear motorcarriage went right through 20mm aluminium endplate.
 
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Offline MR

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Re: Pick and place build, openpnp
« Reply #38 on: October 07, 2019, 02:31:12 pm »
I was talking about LINEAR motors.
Those do not have any physical resistance (like a ballscrew or belt) which can slow rhem down, they can easily do 20G acceleration.
I have seen the damage it could do , a 1m linear motorcarriage went right through 20mm aluminium endplate.

oh thanks didn't know about those yet! However I really think that the X/Y configuration is just one part and not the bottleneck of a fast pick and place machine ... far before that the bottleneck will be the pick and place head and feeders.
« Last Edit: October 07, 2019, 02:35:12 pm by MR »
 

Offline Kjelt

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Re: Pick and place build, openpnp
« Reply #39 on: October 07, 2019, 03:00:39 pm »
I agree on that.
It amazes me that there are little new innovations in the feeder field.
Paper tapes with plastick cover is just so clumsy.
Only the bulk component  piezo shakers which are rediculous expensive are new developments.
 

Online SMTech

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Re: Pick and place build, openpnp
« Reply #40 on: October 07, 2019, 03:32:55 pm »
Where do they evolve too? Tiny parts with tiny legs and an orientation need to be presented to the pick head somehow in a predictable fashion without being at risk of damage, I don't think there is a way round tape with pockets for many items. The piezo thing could perhaps be extended to more parts 2-pin if you could make that feeder just as small as a tape feeder but those bulk parts, come in a tape its just there's a whole lot more in each pocket.
 

Offline Kjelt

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Re: Pick and place build, openpnp
« Reply #41 on: October 07, 2019, 05:35:15 pm »
True for asymetric and fragile parts but for the jellybean resistors, caps and diodes it is such a shame.
For resistors the time to sort , package plus packaging material itself outweighs the component costs, silly huh?
But I am going offtopic so will let it rest.
 


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