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Bar feeder Imeca Boss 338 problem with last part length

TauRunUm

Aluminum
Joined
Feb 18, 2021
I am not that much familiar with this bar feeder, I worked with old FBM, Imeca bar feeder is connected to 10 axis swiss lathe and other folks are operate it. It was okey until recently when we start getting poorer quality bar stock.

Bars arent same length and part have threaded hole somewhere on middle of part so sometimes when bar is shorter (only couple of mm) last part would be shorter too and then drill bit will hit edge and broke and sometimes thread tap will broke too. In past this problem wasnt that big of issue but supplier of bar stock is quite worse then was and we cant change supplier, dont know why and not my job to know.

To make problem worse we need to start using non standard micro carbide drill bit because we want to form thread not tap it, and that drill will for sure break and it isnt cheap either.

But such problem doesnt exist on old bar feeder on Star swiss which I run simpler parts.

I never got shorter last part. On FBM I would set stop switch manually as explain in instruction (part length + width of part off tool).

So I try to help folks which use Imeca but I dont see anyway to do something like that, I read manual for setting up Imeca but from what I got it do calculations based on value you put using remote keyboard in parameters so if bar stock length isnt precise bar feeder cant really know length of last part at least that is how I got it and how machine is doing (Parameter 1 and 66)

I find that hilarious I mean on old FBM I can easily setup length last part but on bar feeder which cost like decent cnc lathe I cant.

Did I miss something?
 
Last part ... boy ... that sure seems odd.

I could see the Top Cut being off if odd length bars, but the pusher should know where the end of the bar is always at.

I don't know the Iemca very well yet, but my guess would be that maybe the "Full Forward" (?) parameter may need to be edit back a little bit?

Any chance that the remnants are a little longer than before? Like maybe there is a mechanical obstruction somewhere?

Can you manually run the pusher all the way up and confirm that it is at least as far as the parameter is set to?

No - IDK which parameter.



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Think Snow Eh!
Ox
 
Sounds like you need to change your part length, or max feeding position in the loader parameters. I have seen where the pusher collet will be pushed back by the main collet and drag the bar back making a short part. Then while making the short part the pusher reaches it's max feeding point and changes bars. If your bars are just a tad shorter this could happen if it was set up with a longer bar. The loader measures the bar as it loads and as Ox said if that wasn't happening, the top cut would be off.
 
Problem doesnt happens non stop, so different value of part will not help much. I am confused because logic say bar feeder need to know where pusher collet and how long remnant plus part length, but it look like it doesnt work like that. For example in manual they dont mentioned nothing about remnant length (I could miss that I will read it again) and as it look there isnt simple contact switch like on old FBM, reason could be universal nature of Boss 338 because it can be configure for lot of different solutions so maybe that is why simple switch will not work, so everything is done trough parameters aka programing of bar feeder. Support guy ask me to have video call becuase it would be lot easier to show us what to do.
 
Remnant length will be a default length, not a programmed length.

I expect that you have a parameter that wants to know max forward that the pusher is able to go.
Once you get to that point, whatever bar is still there, is your remnant.
Remnant length will vary with part length. You may have a small (9"?) remnant, or a really long one.

There is likely a prox switch that sees the leading end of the bar when loading.
I am not sure on the Iemca, but the LNS's that I have use one.

Even if is doesn't have one, that should not matter at End Of Bar routine.
It would just vary on Top Cut location.


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Think Snow Eh!
Ox
 
When both generations of my Iemca's load a bar they are measuring it. My loaders are basically the same, with a different control. The process goes:

1. End of bar is reached.

2. Pusher retracts, and ejects remnant while opening channels.

3. New bar drops into channels when they open. At this point the pusher rod has been picked up by the upper channel. At the lathe side of the feeder, at the end of the channels a flag will pop up. When the loader starts pushing the bar into the lathe the material will knock the flag down. The loader will know where the end of the bar is that it is pushing on from the encoder on the motor. This will tell the loader how long the bar is.

4. Next the loader will retract and close the channels. This is when the clamps come up and the material is loaded into the loader collet.

5. Now the loader knows how long the bar is and in turn knows where to push the bar to via the parameters.

6. Usually at this point the lathe will clamp the chuck and finish feeding the new bar out to the top cut position.

Now it will run parts until the end of bar is reached. I think my newer one that has a hand held keypad has a parameter for part length. My older ones I think just have a modification to max feeding position parameter.

I think your loader is not seeing the max feeding position and keeps going making another part, but when you open chuck and grab more material, the back of the collet hits your loader collet and drags the material back causing a short last part. When the last part is being made, the loader is advanced to get to the max feeding position and starts the new bar process. So if you change your max feed position the loader will see the end of the bar has been reached and load a new bar without making a short part and breaking tools.

On my old loaders with the mounted key pad it is parameter 28. I think on my newer one that has the hand held keypad you are supposed to put in part length, I think the loader will then take that number and the max feed position and determine if you have enough material to make another or not.
 
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I agree that I would try shortening the "Max Distance" (or whatnot) parameter a bit and see if the problem goes away.

Any chance that this machine/loader combo has been moved in recent history?
If so, the loader could be a little closer to the machine than previously.


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Think Snow Eh!
Ox
 
As I wrote problem isn't constant that is confusing. It can do x bars with okey last part length. We noticed this though:

Imeca bars.jpg

So while loading bar next bar would be pushed from position indicated by red arrow, we will see tomorrow is that make shorter last part. Setup of length of last part is done by instructional manual and most last parts are okey length.
 
What is your part length? Just as a test you could take a short bar and cut off enough to make it the same as a long bar minus 1 part and see if you get a short piece.

Example:
Part length with cut-off and face amount is 2.00"
Short bar is .25" shorter than normal, cut off 1.75" and see if you get a short part, or just get 1 less part per bar.

The longer the part the more likely the pusher is being pushed back by the main collet and making a short part before hitting the end of bar position.

Another thing to try would be to set a part counter so the machine stops a couple of parts before it should be done. Then watch and see if the bar is being pulled back and making a short part. You would want to do this with one of the shorter bars.
 
TauRunUM -

I work for IEMCA as a Regional Manager. I just came across this post and would like to help you dial this in. Did you ever get a resolution on this, our are you still having random issues with short parts at the end of bar? If so, I have a few questions?

1.) Does the bar feeder zero correctly? (Use 0-Asse)
2.) Have you checked chain tension lately?
3.) Is the measurement flag at the front of the bar feeder functioning correctly?
4.) What type of lathe collet do you have on the lathe side? A pull-to-close collet has a tendency to pull the material back as its closing.
5.) Are you feeding to bump stop or fixed distance?
6.) Is parameter 1 (end of bar adjustment) = to part length + cut off tool? Are you populating in parameter 6a, 6b or 6c ?
7.) Do you have anything inserted into parameter 10 (closed collet thrust delay)? If you are feeding to a bump stock, change this to a minimum of 1 second
8.) Are parameters 63, 66, and 70 set correctly?
9.) Where do you have the end of the bar subprogram in the main program? At top or bottom? Also, were do you have the EOB check in the subprogram? Typically this doesn't matter however I recently ran into a customer that had a similar problem with short parts on their last part. The issue was that their bar change subprogram was used as a push for their next part in addition to their EOB check which as inserted into the program twice; at the top and bottom of program. Removing the EOB check at the bottom of the subprogram resolved this issue.

If you would like to chat over the phone or would like to talk directly to our phone support team, please send me a PM and I would be happy to provide you with our contact information.

-T
 








 
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