Pick and Place Machine TVM802A / TVM802B

[harry4516]

most of my standard parts are 0603.
I use the nozzle which is recommended for this size.

But there is a big problem with vibrations.
The TVM802 would easily be able to place correctly at 100% speed.
But on the way from pickup to place position the part moves a little bit on the nozzle, probably due to vibration.
So I use only 40 or 50% max speed which is boring.

What can be done to solve this problem ?
Would it help to use a stronger vacuum pump ?
Or should I use a new nozzle, but it is just 2 month old, maybe 50 board.
Or what else could be done ?

[uncle_bob]

most of my standard parts are 0603.
I use the nozzle which is recommended for this size.

But there is a big problem with vibrations.
The TVM802 would easily be able to place correctly at 100% speed.
But on the way from pickup to place position the part moves a little bit on the nozzle, probably due to vibration.
So I use only 40 or 50% max speed which is boring.

What can be done to solve this problem ?
Would it help to use a stronger vacuum pump ?
Or should I use a new nozzle, but it is just 2 month old, maybe 50 board.
Or what else could be done ?

Hi

Unless the pump is broke, it is unlikely you will get a lot by switching it out. Going from 80% of an ATM to 100% of an ATM isn't that big a deal.

Take a look at the tip of the nozzle with a good microscope. If it is damaged, you will be able to see the problem. Check the tip and the seal.

Vibration can come from a few dozen sources. One common one is a micro stepping controller that does not do it's job well. A bit of Google investigation on the controller part number will help you dig into that one.

Bob

[mikeselectricstuff]

most of my standard parts are 0603.
I use the nozzle which is recommended for this size.

But there is a big problem with vibrations.
The TVM802 would easily be able to place correctly at 100% speed.
But on the way from pickup to place position the part moves a little bit on the nozzle, probably due to vibration.
So I use only 40 or 50% max speed which is boring.

What can be done to solve this problem ?
Would it help to use a stronger vacuum pump ?
Or should I use a new nozzle, but it is just 2 month old, maybe 50 board.
Or what else could be done ?

Hi

Unless the pump is broke, it is unlikely you will get a lot by switching it out. Going from 80% of an ATM to 100% of an ATM isn't that big a deal.

or just under-powered,  or too  much leakage. Remember we're  talking  Chinese kit   here,  so maybe they didn't fit   something that was really up to    the job. Another  possibility is there's some ripple in the vacuum, in which case a reservoir before the vacuum valve may help.
 Probably worth experimenting with on the basis that it's a potentially easy fix

Take a look at the tip of the nozzle with a good microscope. If it is damaged, you will be able to see the problem. Check the tip and the seal.

Or maybe  roughen  the    end surface   very   slightly   to increase friction

Also could be something silly like it's not waiting quite long enough during the pick befopre moving off, or not waiting long enough for it to stop before the camera images it.

[uncle_bob]

most of my standard parts are 0603.
I use the nozzle which is recommended for this size.

But there is a big problem with vibrations.
The TVM802 would easily be able to place correctly at 100% speed.
But on the way from pickup to place position the part moves a little bit on the nozzle, probably due to vibration.
So I use only 40 or 50% max speed which is boring.

What can be done to solve this problem ?
Would it help to use a stronger vacuum pump ?
Or should I use a new nozzle, but it is just 2 month old, maybe 50 board.
Or what else could be done ?

Hi

Unless the pump is broke, it is unlikely you will get a lot by switching it out. Going from 80% of an ATM to 100% of an ATM isn't that big a deal.

or just under-powered,  or too  much leakage. Remember we're  talking  Chinese kit   here,  so maybe they didn't fit   something that was really up to    the job. Another  possibility is there's some ripple in the vacuum, in which case a reservoir before the vacuum valve may help.
 Probably worth experimenting with on the basis that it's a potentially easy fix

Take a look at the tip of the nozzle with a good microscope. If it is damaged, you will be able to see the problem. Check the tip and the seal.

Or maybe  roughen  the    end surface   very   slightly   to increase friction

Also could be something silly like it's not waiting quite long enough during the pick befopre moving off, or not waiting long enough for it to stop before the camera images it.

Hi

The "obvious" thing that neither one of us came up with:

Go to a bigger nozzle, recommendations aren't always right.

That may or may not be possible with a specific small part.

On the B model the nozzles are more or less Juki standard. You probably can find other ones. The rubber on a real Juki nozzle might have more grip.

Bob

[sergeil]

I place loads of 0603 and 0402 parts with the smallest nozzle, at 100% speed.

Some ideas:

Do make sure you don't have some paste (or even a component!) stuck inside the nozzle. Use a needle to clear it. I had to do it once to make the pressure sensor work well again.

Does the prick needle ever get stuck on one of the reels? If the pickup location is not set correctly (ex slightly too close to one of the ends) that will hurt you. Fixed with re-calibrating the position of the pickup.

Check that your tape collector is not too tight. If it's too tight it will move the tape just a bit between the "prick" and pickup steps, which could mean you're not 100% on the part with your nozzle.

The machine requires a really solid surface, if operating at 100% speed my table is shaking quite a bit but doesn't seem to affect placement too much.

[harry4516]

I place loads of 0603 and 0402 parts with the smallest nozzle, at 100% speed.
...

do you use the 502 or 503 nozle for your 0402 and 0603 parts ?

[ar__systems]

Or maybe  roughen  the    end surface   very   slightly   to increase friction

No, don't try that. Rough surface means more leakage. Instead you need to polish the surface as much as possible.

On my machine I had the problems with vibration as well and to avoid any guesses about the quality of the built in pump I simply use a big ass external vac pump that I keep in the next room.

[mikeselectricstuff]

Or maybe  roughen  the    end surface   very   slightly   to increase friction

No, don't try that. Rough surface means more leakage. Instead you need to polish the surface as much as possible.

On my machine I had the problems with vibration as well and to avoid any guesses about the quality of the built in pump I simply use a big ass external vac pump that I keep in the next room.

If a small amount of leakage makes a difference then the vacuum flow rate is too low.

[harry4516]

...
On my machine I had the problems with vibration as well and to avoid any guesses about the quality of the built in pump I simply use a big ass external vac pump that I keep in the next room.

When buying a vac pump for that purpose, what are the right parameters for airflow, vacuum and others ? Or buy the biggest one available ?

[rx8pilot]

...
On my machine I had the problems with vibration as well and to avoid any guesses about the quality of the built in pump I simply use a big ass external vac pump that I keep in the next room.

When buying a vac pump for that purpose, what are the right parameters for airflow, vacuum and others ? Or buy the biggest one available ?

I use a 1/4hp rotary vane pump from Gast with a 5gal storage tank. It is enough to supply vacuum for a couple of machines in addition to a few manual pickup tools on my benches. It holds about 26in of Vac but I am not sure what the flow rate is. I was more concerned about the depth of vac than the flow rate. The deeper the vac, the more stable the part is. The flow rates are rather tiny on P&P machines.

[ar__systems]

The flow rate is tiny that is true, but that parameter determines how fast the pump recovers the vacuum. Every time a pick up occurs the pump has to swallow a bit of air. (The air inside the tubing from the solenoid to the nozzle.) The faster it does it, the faster the vacuum at the pick up nozzle reaches the maximum. I think the main issue with built-in pump is actually low flow rate.  The max vac level is not that bad, I think it was like 560mmHg, and my big one reaches 670mmHg. So only 20% less holding power. But it is very (relatively) slow at recovering vacuum. Keep in mind that if it takes a second to recover, that's almost as long it takes for the part to travel from pick up to placement.

[ar__systems]

Storage tank is actually a very good idea. It allows to get away with a less capable pump.

[rx8pilot]

Storage tank is actually a very good idea. It allows to get away with a less capable pump.

I am very happy I added that to the system - and it was not expensive at all. I did have to find a high-flow passive vacuum check valve to prevent the vac from pulling air in from the pump when it cycles off. Regular check valves are useless.

These are fantastic : http://www.vaccon.com/SearchResult.aspx?KeyWords=VCV

[harry4516]

so it may be sufficiant to add a storage tank to the existing pump in the 802 ?

[mikeselectricstuff]

I always thought the idea of a vacuum "storage" tank a little odd....
Is it full of "empty"...?
 

[rx8pilot]

I always thought the idea of a vacuum "storage" tank a little odd....
Is it full of "empty"...?

It's completely full of nothing.

so it may be sufficiant to add a storage tank to the existing pump in the 802 ?

Probably. Does the pump run continuous when the machine is on? It kind of acts like the output filter cap on a power supply - smooths out the vacuum.

[harry4516]

it runs as soon as a pick&place job is started.
I cannot find a storage tank for vacuum, but its available and cheap for compressed air.
These tanks should also work for vacuum ?

[rx8pilot]

Any compressed air tank is fine - that is what I use. It's actually a tank from the air brake system on a big truck.

[ttsthermaltech]

Not sure of the TVM802, but on the new TVM920, Qihe recommends (and supplies with the machine) to install an o-ring in the groove of the nozzle before installing in nozzle holder on machine. The holders on the TVM920 are magnetic, so not sure if the TVM802 is the same. They claim (and I agree) that any leakage makes a difference when trying to move fast and keep parts in place.

[harry4516]

yes, the 802 also has the o-ring in the groove of the nozzle.

I looked for some vac pumps,
Most of them do 26in (abt 85% vacuum),
some pumps (oil) go down to 99,8% vac. This is a very good vac, but I'm not sure if the parts and tubes in the TVM802 can handle that. So I will probably go with the 26in pump.

[ar__systems]

Not sure of the TVM802, but on the new TVM920, Qihe recommends (and supplies with the machine) to install an o-ring in the groove of the nozzle before installing in nozzle holder on machine. The holders on the TVM920 are magnetic, so not sure if the TVM802 is the same. They claim (and I agree) that any leakage makes a difference when trying to move fast and keep parts in place.

I think you are confusing things here. There is no magnetic holder per se. The rotational steppers however are magnetic and will hold the nozzle in place, but that's just side effect. o-ring is a must. Everything I said before was with o-rings in place.

[ar__systems]

yes, the 802 also has the o-ring in the groove of the nozzle.

I looked for some vac pumps,
Most of them do 26in (abt 85% vacuum),
some pumps (oil) go down to 99,8% vac. This is a very good vac, but I'm not sure if the parts and tubes in the TVM802 can handle that. So I will probably go with the 26in pump.

There is little pressure difference between 85 and 99% vacuum. Going from 0 to 85 % is 13PSI difference. from 85 to 100 - only 2PSI. It is not worth it, but the tubes will hold just fine.

[rx8pilot]

If 26in does not work, your machine is bad. My machine ill run full speed 3600CPH at 20in just fine.

[uncle_bob]

yes, the 802 also has the o-ring in the groove of the nozzle.

I looked for some vac pumps,
Most of them do 26in (abt 85% vacuum),
some pumps (oil) go down to 99,8% vac. This is a very good vac, but I'm not sure if the parts and tubes in the TVM802 can handle that. So I will probably go with the 26in pump.

There is little pressure difference between 85 and 99% vacuum. Going from 0 to 85 % is 13PSI difference. from 85 to 100 - only 2PSI. It is not worth it, but the tubes will hold just fine.

Hi

Speaking of tubes, simply adding a roll of tube to a system like this is a "poor man's" way to add a reservoir.

Bob

[ttsthermaltech]

I can only speak for the TVM920, which obviously is different. The TVM920 actually does have magnetic nozzle holders, as the holder is not directly connected to the stepper motor. It is offset with a belt drive, with about a 3:1 reduction for more accuracy in rotational angles.

But glad to hear the o-rings are in place on the 802's.

Sorry if I added some confusion....

Not sure of the TVM802, but on the new TVM920, Qihe recommends (and supplies with the machine) to install an o-ring in the groove of the nozzle before installing in nozzle holder on machine. The holders on the TVM920 are magnetic, so not sure if the TVM802 is the same. They claim (and I agree) that any leakage makes a difference when trying to move fast and keep parts in place.

I think you are confusing things here. There is no magnetic holder per se. The rotational steppers however are magnetic and will hold the nozzle in place, but that's just side effect. o-ring is a must. Everything I said before was with o-rings in place.