[TMToronto]

I am in the process of setting up my Jianken JGL 2.2Kw ATC spindle. So far all is working well, and the tool logic and ATC routine of my Masso G3 is controlling everything as expected.
I am however wanting to better understand the role of the Air Return in the functioning of my spindle, and am hoping someone can better explain it to me.
When I asked my contact at Jianken, the replies were as follows:

1)
"Air return" should be turned on after the "air inlet" and "dust removal".
"Air return" can not keep under pressure until the next tool change. Otherwise, it will be a problem. The air from "air return" comes out of the spindle taper.
I don't know why some customers want to keep the "air return" under pressure.

2)
Actually, if you ignore "air return", the spindle can also work normally, especially when the spindle is new. Because there are springs in the spindle.
"Air return" only work for a few seconds during each tool changer. We can not keep the "air return" continuously energized.

My manual wants Air Return to be pressurized for 5 seconds after the new tool is clamped, then exhausted.
I believe I understand that the Air Intake when pressurized pushes against the internal spring/washers allowing the pull stud clamp to open/exhausting it allows the reverse and the tool is clamped.
What I am not clear on is exactly what the Air Return does internally within the spindle, and before I receive another somewhat unclear reply from Jianken, I thought I would ask the forum.

I appreciate any insights that can be offered.

[mactec54]

I am in the process of setting up my Jianken JGL 2.2Kw ATC spindle. So far all is working well, and the tool logic and ATC routine of my Masso G3 is controlling everything as expected.
I am however wanting to better understand the role of the Air Return in the functioning of my spindle, and am hoping someone can better explain it to me.
When I asked my contact at Jianken, the replies were as follows:

1)
"Air return" should be turned on after the "air inlet" and "dust removal".
"Air return" can not keep under pressure until the next tool change. Otherwise, it will be a problem. The air from "air return" comes out of the spindle taper.
I don't know why some customers want to keep the "air return" under pressure.

2)
Actually, if you ignore "air return", the spindle can also work normally, especially when the spindle is new. Because there are springs in the spindle.
"Air return" only work for a few seconds during each tool changer. We can not keep the "air return" continuously energized.

My manual wants Air Return to be pressurized for 5 seconds after the new tool is clamped, then exhausted.
I believe I understand that the Air Intake when pressurized pushes against the internal spring/washers allowing the pull stud clamp to open/exhausting it allows the reverse and the tool is clamped.
What I am not clear on is exactly what the Air Return does internally within the spindle, and before I receive another somewhat unclear reply from Jianken, I thought I would ask the forum.

I appreciate any insights that can be offered.

It's quite simple, and is not an air return, that is just a word that has not translated into English very well.

It is just an air blast used when you do a Tool change, this is to clear the dust chips away from the taper and in some cases to help / assist the Tool removal if the Tool is sticking in the taper, so the solenoid needs to turn on with the tool change and off once the new tool has started to enter the taper, 0ff before the Tool is fully inserted

Now the Tool Change and the Tool Blast are normally (2) different connections, for the Tool Change the solenoid will open pushing air into the Pneumatic cylinder, this too is an 0n / 0ff function also some of these spindles combine the air blast with the Tool change.

So how many air inlet ports do you have on the spindle, this will determine how many solenoid valves you need

[TMToronto]

Thank you as always for sharing your expertise. In my case I have four pneumatic hoses operating the various functions of the ATC - please see attached pneumatics diagram supplied by Jianken.

From my understanding, the 'Air Return' does appear to have a different function, as I also have have a separate 'Dust Removal' solenoid/line that serves the function you speak of.

I have also attached the section of the manual that describes the tool change process, to see if that helps.

Jianken has always been very responsive to my requests for information, and I have written them again in hopes of getting a more technical (what happens mechanically inside the spindle when Air Return is pressurized and exhausted) explanation of the functioning of the Air Return. I will update the the read once I hear back, which is usually within 1 to 2 days.

In the meantime, maybe the attachments I provided are of help.

[mactec54]

Thank you as always for sharing your expertise. In my case I have four pneumatic hoses operating the various functions of the ATC - please see attached pneumatics diagram supplied by Jianken.

From my understanding, the 'Air Return' does appear to have a different function, as I also have have a separate 'Dust Removal' solenoid/line that serves the function you speak of.

I have also attached the section of the manual that describes the tool change process, to see if that helps.

Jianken has always been very responsive to my requests for information, and I have written them again in hopes of getting a more technical (what happens mechanically inside the spindle when Air Return is pressurized and exhausted) explanation of the functioning of the Air Return. I will update the the read once I hear back, which is usually within 1 to 2 days.

In the meantime, maybe the attachments I provided are of help.

Dust removal= Dust/ chip Blast this works at the same time as the Tool is being changed their plumbing diagram is correct

Air seal= a continuous air flow when the Spindle is running, this keeps and dust / chips Etc. away from the front spindle Bearings, plumbing diagram is correct

Make sure you have a dry air supply, or you will have Bearing and pneumatic problems

[TMToronto]

Thank you. I have my main pneumatic line first going through a Motor Guard M60 filter, followed by another smaller filter, before reaching my ATC specific manifolds and regulators/valves.

Understanding exactly what the Air Return does is more to satisfy my need to know the inner working of things, as currently all is working well. Still, I am hoping Jianken replies with a clearer explanation of the Air Return mechanics and the role it plays during tool changes..

I am still slowly fine-tuning the various feed rates used during the pick and place tool change logic under the control of my Masso G3. I am under a minute from the time when the spindle leaves a random work coordinate until the tool is changed and it returns to the same spot, and I feel I can still decrease this while balancing efficiency with correct and safe tool changes. This is not for commercial use, so getting the absolute fastest tool change is not my end goal for my CNC build.

[mactec54]

Thank you. I have my main pneumatic line first going through a Motor Guard M60 filter, followed by another smaller filter, before reaching my ATC specific manifolds and regulators/valves.

Understanding exactly what the Air Return does is more to satisfy my need to know the inner working of things, as currently all is working well. Still, I am hoping Jianken replies with a clearer explanation of the Air Return mechanics and the role it plays during tool changes..

I am still slowly fine-tuning the various feed rates used during the pick and place tool change logic under the control of my Masso G3. I am under a minute from the time when the spindle leaves a random work coordinate until the tool is changed and it returns to the same spot, and I feel I can still decrease this while balancing efficiency with correct and safe tool changes. This is not for commercial use, so getting the absolute fastest tool change is not my end goal for my CNC build.

The air return as they call it, is just pushing the piston in the cylinder back up, so it is no longer in contact with the spindle draw bar.

Never activate the ATC with the spindle running, as if you do, it will Spin Weld the Piston rod to the end of the Draw Bar, it's quite a job to repair if this happens

Regular filters don't give you dry air you need an air dryer

Here is a very basic diagram of what is happening

[TMToronto]

Thank you again for your continued advice.
Your explanation makes sense, and the diagram is similar similar to those that I saw when researching the 5/3 solenoid valve I installed as per the installation diagram. The part I wasn't sure about, and I suppose is what I am asking Jianken to explain, is why there is the added solenoid on the Air Return line (They say because it should not stay pressurized, so that I understand, but not sure why). The 5/3 valve would automatically pressurize the 'A' line without the added valve, and would this pressure not act with not against any spring/washers being used to clamp the pull stud?

As for an air dryer, I had read in many forums people using these for both small particulate capture as well as moisture, but if this is not your recommendation then I am open to alternatives. I was going from their manual which states:

"Motor Guard sub-micronic compressed air filters are designed to remove condensed moisture, oil aerosols and
particulates from compressed air. Used properly, these filters will provide clean, dry, oil free air for critical industrial
applications."

I would appreciate it if you have suggestions for cost effective (I know, a relative term) solutions. I have seen some that use chambers with desiccant media, perhaps those are better for my use case.

[mactec54]

Thank you again for your continued advice.
Your explanation makes sense, and the diagram is similar similar to those that I saw when researching the 5/3 solenoid valve I installed as per the installation diagram. The part I wasn't sure about, and I suppose is what I am asking Jianken to explain, is why there is the added solenoid on the Air Return line (They say because it should not stay pressurized, so that I understand, but not sure why). The 5/3 valve would automatically pressurize the 'A' line without the added valve, and would this pressure not act with not against any spring/washers being used to clamp the pull stud?

As for an air dryer, I had read in many forums people using these for both small particulate capture as well as moisture, but if this is not your recommendation then I am open to alternatives. I was going from their manual which states:

"Motor Guard sub-micronic compressed air filters are designed to remove condensed moisture, oil aerosols and
particulates from compressed air. Used properly, these filters will provide clean, dry, oil free air for critical industrial
applications."

I would appreciate it if you have suggestions for cost effective (I know, a relative term) solutions. I have seen some that use chambers with desiccant media, perhaps those are better for my use case.

If you have an automatic water drain this will help to keep the water out of your spindle, the filters can only do so much, your airlines also can help if designed to have a drop leg where the water will go and can be drained off, the air is normally taken off above this point around 18" to 24" above this works as a water trap before it gets to the filters

The solenoid valve that is being used may not have an exhaust, when it is in the off position, so you need the other valve to release the pressure on the return airline to the spindle cylinder.

This can be done with (1) valve if you have the right solenoid valve, (most likely a double acting solenoid valve) so once the piston is returned to the top of its stroke, the sensor will turn off the solenoid valve, the solenoid valve if spring return will return to the center and exhaust the air from the return line this way you would not need the second solenoid valve

If your solenoid valve has center return exhaust, then you won't need the other solenoid valve

[mactec54]

Here is what a drip leg / drop leg is for an airline water trap, this can have an auto drain on it as well.

[TMToronto]

I appreciate the time you are taking to explain this. Happily from reading I had done it makes sense.
My 5/3 solenoid valve is single acting, and not spring return, so I believe the 3/2 solenoid valve I added to the 'A' line is indeed needed as my controller will open it for 6 seconds to pressurize the Air return, then when it deenergizes the line will exhaust, releasing pressure in the Air Return until the next tool change. As mentioned this all seems to be working as expected.

My second filter inside my pneumatic enclosure has an automatic water drain. I also had added drop legs - without knowing - as part of the way I did the piping. One thing I could do is add a brass valve to drain any accumulated water at the drop leg.

Thanks again.

[TMToronto]

Here is what I will take as the last word from Jianken when I asked again for an explanation of the functioning of the Air Return...

"Sorry to tell I don't have a diagram or photograph of the spindle when the air return is pressurized.
As we know, "Air Return" is designed to simply assist the springs in returning the drawbar & air cylinder.
Actually, if you don't use "air return", it's also OK especially for the new spindle since there are springs in the spindle."

[mactec54]

I appreciate the time you are taking to explain this. Happily from reading I had done it makes sense.
My 5/3 solenoid valve is single acting, and not spring return, so I believe the 3/2 solenoid valve I added to the 'A' line is indeed needed as my controller will open it for 6 seconds to pressurize the Air return, then when it deenergizes the line will exhaust, releasing pressure in the Air Return until the next tool change. As mentioned this all seems to be working as expected.

My second filter inside my pneumatic enclosure has an automatic water drain. I also had added drop legs - without knowing - as part of the way I did the piping. One thing I could do is add a brass valve to drain any accumulated water at the drop leg.

Thanks again.

Yes, the drop-leg must have a drain, as that is where most of the condensate will settle, either an auto drain or a ball valve works as long as you remember to drain it at least once a week.

[mactec54]

Here is what I will take as the last word from Jianken when I asked again for an explanation of the functioning of the Air Return...

"Sorry to tell I don't have a diagram or photograph of the spindle when the air return is pressurized.
As we know, "Air Return" is designed to simply assist the springs in returning the drawbar & air cylinder.
Actually, if you don't use "air return", it's also OK especially for the new spindle since there are springs in the spindle."

They are saying basically the same as what I said, except they are saying, the piston in the cylinder has a return spring that can return the piston back up, and no air return is needed, when it is new

[TMToronto]

I believe so.
I am not sure why I didn't think of this before, but I remembered a video I found quite a while ago - may even have shared it in this forum if memory is correct - of someone 'dsisecting' the same type of spindle I have.
When I watched it again at the ~18:20 mark he shows two sections that are cylinder/pistons, each with a push rod, the second unit having the pull stud rod/clamping mechanism screwed to it.
His description makes what you and Jianken are explaining much clearer - I had a completely different mental picture of the tool change mechanics inside the spindle.
I can now see how pressurizing and exhausting air from this second (Air Return) cylinder/piston unit would be important long term.

Here is the video link - https://www.youtube.com/watch?v=7jd1AieyO_0

On a related note, the main reason for his spindle failure I believe is that 'shaft welding' you mentioned in an earlier post here. If you continue watching the video he shows the damage caused by this.