SAE indexable porting/bad finish

[steveo25]

We are using a metcut #8 indexable porting tool on a mori nl-3000y mill/turn and we are having a hard time getting a good finish on the o-ring surface. We are running at 1500 rpm to start with a .004 chipload and once it reaches the o-ring suface we turn it down to 1000 rpm and then when it gets to the counter bore it is turned down to 390 rpm. It starts to chatter when it gets down to the full depth. We are not porting on a flat surface so we have to bring the tool down until the counterbore cleans up all the way. The material is a 6.0" piece of 1040 steel. Does anyone have any recommendations?

Thanks for your time

[Guest CNC Apps Guy 1]

When doing porting, it's CRUTIAL to have minimal stock everywhere possible.

[steveo25]

When doing porting, it's CRUTIAL to have minimal stock everywhere possible.

 

Ok, at first we came in with an endmill to just rough out the counterbore and then came in with a cemented carbide porting tool but it kept spiking our load meter. It took alot of time so we got an indexable porting tool in for test but im starting to think the first way is the route we are going to have to take.

Thank you for the response

[jeff]

If you're getting chatter and spiking the load meter, my guess is that you don't have a stable work setup and not enough horsepower to push the tool.

Can you do the port in a different machine or make a more rigid setup?

Porting has a lot of surface contact, rigidity is crucial as well.

[steveo25]

If you're getting chatter and spiking the load meter, my guess is that you don't have a stable work setup and not enough horsepower to push the tool.

Can you do the port in a different machine or make a more rigid setup?

Porting has a lot of surface contact, rigidity is crucial as well.

 

Yea our main problem is the live tooling spindle on this machine is only 7.5HP and the torque is minimal at low rpms that is the main reason we went to the indexable because you can run the tool faster and get optimum torque. We do alot of these parts so we need to find a full proof way of doing them. This is the only mill/turn we have, we used to do them on a 50 taper mill with a haas indexer but the setup took some time. We tried bringing the tailstock in for added support and its hard to beleive but it made the chatter worse.

[jeff]

Not sure of what the part looks like, but could you do the porting before some of the other material is removed? Maybe the part would be more stable and not want to chatter?

Also, If your tailstock is making the chatter worse, is your pressure to light? too heavy to where it's bending the part?

Just tossing out ideas here.

[steveo25]

Not sure of what the part looks like, but could you do the porting before some of the other material is removed? Maybe the part would be more stable and not want to chatter?

Also, If your tailstock is making the chatter worse, is your pressure to light? too heavy to where it's bending the part?

Just tossing out ideas here.

 

The part has a I.D. bore through it that is drilled and roughed from the first op. The porting is done on the 2nd op. That was a pretty good idea but the port comes through the outside of the part into some I.D. oil grooves. I would be afraid of the interupted cut with the groove tool. We didnt try turning up the thrust on the tailstock, that may have helped. The part is 6.75" long and we have a jaw depth of 1.125".

Thank you for throwing these ideas out there, im new to programming and havent been in the industry very long so every bit of advice helps tremendously.

[Mic6]

im new to programming and havent been in the industry very long so every bit of advice helps tremendously.

 

Glad to see you're using the great resources available to you

[steveo25]

Yea definely this forum has been a great learning tool for me. Just a quick update we have been adjusting our change in speeds and feeds in our sub program and it looks like we are getting a decent finish now.

[jeff]

Sometimes a little change in speeds and feeds will make all the difference in the world.

[steveo25]

Yea we didnt adjust it much at all. I think the main thing was to get the adjustment timing down just right. We use a sub program so we can kick down the feeds and speeds for the changing diameters on the tool, it just took sometime to get it dialed in. When I asked the manufacture what they recommended they just gave me one straight rpm and a chip load and it seemed way to fast for our application. Thanks again for all the help

[Tim Johnson]

Yea our main problem is the live tooling spindle on this machine is only 7.5HP and the torque is minimal at low rpms that is the main reason we went to the indexable because you can run the tool faster and get optimum torque. We do alot of these parts so we need to find a full proof way of doing them.

 

If your indexable tool is coolant thru then try kicking the rpm up 20% over recomendations, drop the chip load 10%-20% and use a chipbreak cycle to keep the shavings manageable. Add a .005/.010 C'bore cycle for the finish cut at recommended speed/feed.