Unattended machining

[Philcott]

I am wondering if anyone on here has experience with running aluminum parts on a MTM.

 

The area I'm interested in is how to make sure, on finishing cuts on id bores, you don't have any chip issues such as bird nests wrapping around the bar and causing problems. High pressure coolant? Special inserts.

 

It's all about chip evacuation.

 

Thanks.

[kh012]

we use high pressure coolant thru the tool when possible. for insrts we try and use ones with a high posi rake, this will help pull the chips

out of the bore. if the pressure is good it tends to break up the chips.

 

HTH Ken

[chris m]

On some parts when I back out of the bore with the rough boring bar I'll G04 in front of the part with the coolant flushing the hole out. If you're wrapping too many chips around the boring bar, you could make a ring to set screw to the tool plumbed with coolant from an adjacent empty station; index to the dummy station with the coolant on and flush the chips off. Air blast is useful for this also.

 

C

[Jroc85]

Adjusting your feed and speed could also prevent the chips from being stringy and wrapping aroung the bar.

[Philcott]

we use high pressure coolant thru the tool when possible. for insrts we try and use ones with a high posi rake, this will help pull the chips

out of the bore. if the pressure is good it tends to break up the chips.

 

HTH Ken

 

Ken,

 

What would you consider hi pressure? 200, 300 or like 1000psi?

[Philcott]

On some parts when I back out of the bore with the rough boring bar I'll G04 in front of the part with the coolant flushing the hole out. If you're wrapping too many chips around the boring bar, you could make a ring to set screw to the tool plumbed with coolant from an adjacent empty station; index to the dummy station with the coolant on and flush the chips off. Air blast is useful for this also.

 

C

 

Thanks Chris. We usually can deal with the roughing tools ok it's on long, fine feed finishing passes that the this chips will wrap around the bar. Often the problem is not chips in the part but on the bar or turning tool itself.

[GoetzInd]

1000PSI is gonna help a lot when trying to run lights out. Mist collector and coolant chiller might be needed also to hold any tight tolerances though... $$$$$$$$

 

Mike

[chris m]

Phil, I feel your pain, you can never get enough feedrate on finish tools to break a chip

[Philcott]

Adjusting your feed and speed could also prevent the chips from being stringy and wrapping aroung the bar.

 

We've tried many combinations of speed and feed to no avail. These parts get polished and buffed to a mirror finish so we are limited in our finish feed rate.

[T_MALENA]

High pressure coolant to break the chip. Speed/feed adjustment & insert style also help. And a air blast at the base of the boring bar to keep chips from nesting. Had a few jobs where I just started at the bottom of the bore & bored out to the end leaving the chips in the part. It also prevented the nest from scratching the ID finish.

[robk]

This is what we use CoroTurn HP... They work great for breaking chips, but keep in mind that we only run them in Hi-Temp alloys and not aluminum.

[kh012]

Ken,

 

What would you consider hi pressure? 200, 300 or like 1000psi?

 

it all depends on the size of the nozzel, really small and 200/300 might be ok, but not much beats 1000 psi.

we use cooljet pumps that put out around a 1000 psi thru a 3/16 dia. "QPM" is a company that has a wide

selection of coolant lines, nozzels etc.

 

Ken

[High Performance]

might need to slightly increase the depth of cut, also I agree with insert suggestions --> very sharp and high positive geometry and chip breaker. 1000psi coolant and mist collectors, and also you will want to monitor tool life during the day, then set the machine to use backup tools (ie change tools after so much tool life, or parts cut, Mazaks have the capability built in, other machines I cant really comment, but Macros and easily accomplish this) The last suggestion will require some time to fine tune. Also, if your machine has Overload detection, use it. its helpful if a drill welds into the part from built up edges.

[Tim Johnson]

On a job with extruded alum tubing (I think 6060) I left around .03 per side and put in a 20 pitch thread in before finishing. That worked very well. I would try increasing the DOC first though for time purposes.

 

 

[Philcott]

Thanks for all the ideas. If we get the machine I'll put some of them to the test.

 

I think we'll know today if the boss pulls the trigger or not.

[DavidB]

Make sure your leaving at least the radius of the finishing insert as stock!

[chris m]

Make sure your leaving at least the radius of the finishing insert as stock!

 

That is certainly what you want to do, in theory, but I have experienced VERY limited success actually doing it, particularly in thin parts. Is this something you have experience with, or just a "rule of thumb?"

 

C

[robk]

^^^+1 Chris. ^^^

I am aware that's what the catalogs say, as well as the sales reps. In the real world though I have not been succesful implementing that rule ..

[DavidB]

The original question.

 

The area I'm interested in is how to make sure, on finishing cuts on id bores, you don't have any chip issues such as bird nests wrapping around the bar and causing problems.

 

 

So if he is getting a birds nest now yes it can definatly work, it helps break the chip.

[chris m]

Not answering the question, David. Feeding at .5X the nose radius will also break the chip, but you can't hold size or generate the required finish if you're doing something fussy, which is all we do. Rob and I have been doing this for quite awhile and cannot make this "DOC more than the nose radius" thing actually work; if you have succeeded with this I am interested in: material, insert, feedrate, sfm, etc, because I would LOVE to break chips on finishing passes.

 

C

[jas6142]

We have been having a lot of luck using becker pcd inserts with a chip breaker from rani tool.

rani tool

a video here

video

[Philcott]

because I would LOVE to break chips on finishing passes.

 

 

 

There it is Chris. So would I.

[Philcott]

Jas,

 

I'll have a look at those in the morning.

 

Thanks