SMD paste application...

[eSlavko]

Hello...

Does someone use openPnP for paste application. And if yes what head is used. I really like to see that someone has simple design to do paste jetting like in that video.

https://www.youtube.com/watch?v=SZ-Kq2Gkm5Y

(Have just started to build PnP machine)

[Daren Schwenke]

Thanks for sharing that!  You got the gears turning in my head.. 

From the sound of it, I would guess they are using a tiny piezoelectric pump to do the jetting.  I imagine this was not a trivial engineering task though as the paste is quite viscous, so I don't think jetting and simple will end up being in the same sentence again.

I believe the standard approach is to use a syringe and a stepper, but I too have just started building a PnP machine so I'll wait for the experts to chime in.

[eSlavko]

...actually as seen in their website is not piezo. It's just some kind of needle valve and compressed air. And they can shoot 270 dots per second! If we can make reliable 5 dots per second will be really nice. And this thing really jets dots and not drag with some kind of needle (no Z motion required)

[Daren Schwenke]

Yeah, I saw the air line to the back of the cylinder containing the paste/glue.  I'm guessing that just turning a valve on the solder paste side on/off rapidly is still not enough energy to make it fly though (at least at standard air compressor levels anyway).

So that left either a solenoid or piezo pin type pump and/or some form of air assist to get the material moving.  Probably both.  

But this napkin engineering is all just happening in my head so I could be full of it.

[Michael Anton]

My guess is they keep constant pressure air on the syringe, and use a needle valve to release the paste.  That would be pretty fast.  I don't think you could get speed like that if you controlled the air side, as paste doesn't like to move that fast.

[Daren Schwenke]

That's what I was (poorly) saying.  The static air pressure keeps the liquid moving, but a valve on the paste side deploys it.  

But... I was questioning if the paste would jet like that though under normal air (120-160psi) pressures given how small the orifice would need to be and how thick the paste is.

I was theorizing that the pin used to allow the paste to flow perhaps also imparts some energy to it, or that they had a directed laminar cone of air.

With the pin idea, how far it retracts controls how much paste to jet, but then the return stroke of the pin sealing off again actually causes the jetting.

This is all assuming that it acts like I think it does of course as I've never pressurized a tube of solder paste before.

I suppose the cylinder could actually be generating hydraulic pressure as well which would solve the energy issue as well.

As in air pressure in a larger cylinder mechanically coupled to paste pressure in a smaller one.

Perhaps someone here actually knows...

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[Daren Schwenke]

Well I bothered to do the research and it seems at least one company is doing what I theorized.

http://www.fcc.chalmers.se/focus-areas/electronics/simulation-of-jet-printing/

This of course still doesn't answer the author's original question.  Sorry for hijacking the thread...  I get excitable.  

Anyone else?

[eSlavko]

I see that diagram...

[Daren Schwenke]

Yep.  That's the pneumatic version of the same idea.

[eSlavko]

Seems that this can be doable. I think electromagnetic can be even smaller. Just thinking on the old dot matrix printers and their hammers. But for jetting I assume that nozzle geometry is important too.

Dne četrtek, 08. februar 2018 08.30.22 UTC+1 je oseba Daren Schwenke napisala:

[Daren Schwenke]

Automotive fuel injectors have a very similar design.  The nozzle is completely wrong of course and I'm not sure the plunger closing will generate the desired impulse, but it may be something to look at.  They will easily operate at the desired frequency and at 12v.  

There are probably a lot of gotchas like a lot of extra paste for the inline designs and possible lubrication issues, but If they can be adapted, that's an $18 solution to a $1000 problem.

[Daren Schwenke]

On Thursday, February 8, 2018 at 2:44:28 PM UTC-5, Daren Schwenke wrote:

Automotive fuel injectors have a very similar design.  The nozzle is completely wrong of course and I'm not sure the plunger closing will generate the desired impulse, but it may be something to look at.  They will easily operate at the desired frequency and at 12v.  

[eSlavko]

Seems close to that we need.
But by design I see that fluid path is through entire device (from top to bottom) and path is probably very narrow. That's good for diesel as they have lubrication property but not for solder paste as they are little abrasive and does have particles of solder. But indeed this can be nice source for parts we needed, just need to rearrange them and of course change nozzle itself. I don't have part here but I assume that all thing is pressed together and not so easy to open it.

[Daren Schwenke]

Yeah, the ones I've changed in my cars at least were all crimped shut on both ends.  Like 10 ton press, perfect circle type crimped.  That lip would need to be ground off to get them apart.

The other injectors I've found with a more direct path unfortunately also include a hydraulic amplifier. They are designed to open faster by bleeding off some fuel pressure via a return line similar to a quick exhaust valve, so they won't work.

[Mike Menci]

Hello eSlavko

Here is a option in this video / speed is slow but that could be faster: https://www.youtube.com/watch?v=w3fm-gYnoMY&t=9s

Mike

[eSlavko]

What pump motor operate here? Air seems to be just backpressure.

[Ondrej Janovsky]

Hi, 

I want to use OpenPNP for dispensing. For this time, I tested dispensing on my 3D printer with air presure paste dispensor YDL 983A . I used rpt2pnp tool for GCODE generating.

There is some video https://photos.google.com/photo/AF1QipPZwdUXQcvT3Bovn0z3zGUMlj5bmguvgx9MPDku

Regards

   Ondrej

  

Dne středa 7. února 2018 17:44:42 UTC+1 eSlavko napsal(a):

[evilwulfie]

I love the idea of fast paste dispensing. That said i cant see the time investment in creating such a beast when
applying paste with a stencil is fast and painless.

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[eSlavko]

Did you make stencil for 2 or 3 prototypes?

[evilwulfie]

I cut my own using a stencil cutter. search previous messages to this list.

I Make mistakes my software makes mistakes using wrong landpatterns sometimes ( missing past mask )
So buying a stencil can get expensive for one off testing. much less expensive overall to just cut one.

Sure if your going to make 100 of them its worth buying a stainless steel stencil
but for me while prototyping things cutting my own just makes sense

On 2/12/2018 9:20 AM, eSlavko wrote:

Did you make stencil for 2 or 3 prototypes?

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[Daren Schwenke]

This train of thought is going to live only in the realm of brainstorming for at least a couple months, unless I can build it with spare 3d printer parts and a 3d printer.  

My real shop is 1200 miles away right now, but I'm enjoying thinking about it.

Will one of those high wattage blue laser mods for 3d printers do acetate sheets with decent results?  Not a paste dispenser, but less than a full blown laser cutter and fits the niche of just making a few boards..

On Mon, Feb 12, 2018 at 11:29 AM, evilwulfie <evilw...@gmail.com> wrote:

I cut my own using a stencil cutter. search previous messages to this list.

I Make mistakes my software makes mistakes using wrong landpatterns sometimes ( missing past mask )
So buying a stencil can get expensive for one off testing. much less expensive overall to just cut one.

Sure if your going to make 100 of them its worth buying a stainless steel stencil
but for me while prototyping things cutting my own just makes sense

On 2/12/2018 9:20 AM, eSlavko wrote:

Did you make stencil for 2 or 3 prototypes?

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[Olyozz]

found this might help with this project see attached :

also they use jetting solder paist for these types of dispenser by the looks 

[Daren Schwenke]

Nice.  Thank you.

I've been mentally playing with the layout using a 0.1mm M6 thread FFF nozzle repurposed for this.  It's the correct shape internally..

Would need a piezo driven pin, a couple O rings, and a block of AL to hold it all together.  I've found you can get suitable O-rings from a Bic grill lighter.  

I'm wondering if the elements from an ultrasonic cleaner/humidifier could work for the piezo stack.

[eSlavko]

I think in same direction. But as I had bad experience with piezzo will try ordinary electromagnet.

Just wandering how to prevent oozing. I mean paste need to be presurized in reservoir. And having pin to close nozzle seems to be bad idea as paste isn't fluid. Here are a lot to do to get that functionally.

[Daren Schwenke]

On Wednesday, February 28, 2018 at 1:56:24 PM UTC-5, eSlavko wrote:

I think in same direction. But as I had bad experience with piezzo will try ordinary electromagnet.

Just wandering how to prevent oozing. I mean paste need to be presurized in reservoir. And having pin to close nozzle seems to be bad idea as paste isn't fluid. Here are a lot to do to get that functionally.

As I understand it, the pin both closes the nozzle and provides the impulse which actually causes the jetting, hence the reason I think the piezo is a simpler solution.  You can have positive action in both directions.

How long/far you retract controls the amount jetted, but then how fast you close the nozzle controls the actual jetting.  The pressure in the feed system just keeps things flowing to the nozzle and is not by itself enough pressure to actually jet.

[Olyozz]

just stumbled across this patent aplication it basically explains how it all works got to love the internet haha

On Wednesday, 7 February 2018 16:44:42 UTC, eSlavko wrote:

[Joe Eagar]

I thought I'd share this simple (non-jetting) dispenser:

It's an extremely simple concept.  The piston is double racked and is driven by the two motors, as well as a spring that fits inside the rocket-shaped thing on the top (these particular motors are self locking).  A normal solder paste tube fits in a slot at the bottom (that you can't see).  I have tested it and it does work, though I'm still building the rest of my PnP machine so I've not tried it on actual circuit boards.  It does extrude pretty slowly, though theoretically with a strong enough spring it should be able to go faster (I tested it with a really weak spring).

Anyway, I just discovered OpenPNP.  Originally I was going to write my own software and firmware, but OpenPNP looks promising.  I'll make to submit patches if I manage to get it working with my dispenser.

Joe

[Oliver Osbourne]

any vids using this how does it perform 

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[Oliver Osbourne]

any vids using this how does it perform 

On 4 March 2018 at 09:48, Joe Eagar <joe...@gmail.com> wrote:

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