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Turning 304 speeds and feeds help

wdg5555

Plastic
Joined
Mar 16, 2016
I have a few 6"Ø parts with a lot coming out of the ID. I"m not having very good insert life and was looking for some recommendations. Also I'm not finding a way to break the chip very well. Which is especially a problem with my boring bar since it is not a thru hole. Near the bottom of the boring cycle the chips sometimes get crunched up and its a cringe worthy sound.
Any help with speeds,feeds, DOC, and maybe inserts would be greatly appreciated.

Material is 304
Using a positive rake insert on boring bar, Sandvik insert grade 2025. .015 rad
OD tool is negative rake Sandvik insert grade 1125
 
Could try some high feed facing cuts at the bottom. Leave some drilled hole to give some clearance. Maybe some taper on the bottom so you're not crunching into a flat bottom. Light DOC and high feed facing cuts to finish the bottom should break your chip nicely. Don't forget to bump your coolant concentration way up.
Jordy

Sent from my LG-H831 using Tapatalk
 
Still need some key information to help. How big of a drill and how deep before you start boring? Are you rough boring or just making one finish bore pass? What Sandvik chipbreaker are you using...what's the full insert number?

I've never been sucessful in 316SS with consistent chip breaking on finishing passes...with any insert. I also use .015 radius...about .002-.005 ipr and .01" DOC (.02" diameter) depending on finish requirements and or chatter issues.

I do get some success with breaking chips when I start boring larger diameters (larger for me is over 1-1/2" diameter). I use Sandvik TCMT 221 MF 1105 in 316SS, .01" doc, .005 ipr feed, 600sfm, held in a Sandvik dampened boring bar (C5 Capto, SL type bar).

With your 2025 grade you will want to be in the 400 sfm range...about 450 max for finishing cuts.
 
I like to use an coolant thru indexable drill for blind deep bores.

Drill to depth then reduce speed. Call up offset to use periphery insert as boring bar increase feed to get a good chip then go to town. You'll have to stop a bit shorter on depth which each pass so as not to hit center insert. But sometimes that helps to as you create sort of a funnel that washes chips out instead of packing in. Drill is also good as the twist helps pull chips out...thru coolant pushes chips out.

Then go in with boring bar and clean up. 304...sometimes you have to be pretty aggressive to break chips. I also found too heavy of a cut, too fast can make it almost impossible to chip...so back off on DOC, bring up feed...gotta make consistent chips.

Then finish with finish bore tool.
 
Still need some key information to help. How big of a drill and how deep before you start boring? Are you rough boring or just making one finish bore pass? What Sandvik chipbreaker are you using...what's the full insert number?

I've never been sucessful in 316SS with consistent chip breaking on finishing passes...with any insert. I also use .015 radius...about .002-.005 ipr and .01" DOC (.02" diameter) depending on finish requirements and or chatter issues.

I do get some success with breaking chips when I start boring larger diameters (larger for me is over 1-1/2" diameter). I use Sandvik TCMT 221 MF 1105 in 316SS, .01" doc, .005 ipr feed, 600sfm, held in a Sandvik dampened boring bar (C5 Capto, SL type bar).

With your 2025 grade you will want to be in the 400 sfm range...about 450 max for finishing cuts.

I'm using a 2" drill to go down 2". Then using an endmill and smaller boring bar to flatten whats left over from the drill. Then rough and finish.
I'm using WNMG080408-MM inserts on the boring bar.
 
I like to use an coolant thru indexable drill for blind deep bores.

Drill to depth then reduce speed. Call up offset to use periphery insert as boring bar increase feed to get a good chip then go to town. You'll have to stop a bit shorter on depth which each pass so as not to hit center insert. But sometimes that helps to as you create sort of a funnel that washes chips out instead of packing in. Drill is also good as the twist helps pull chips out...thru coolant pushes chips out.

Then go in with boring bar and clean up. 304...sometimes you have to be pretty aggressive to break chips. I also found too heavy of a cut, too fast can make it almost impossible to chip...so back off on DOC, bring up feed...gotta make consistent chips.

Then finish with finish bore tool.

Can you give me some idea of your speeds and feeds.
 
Can you give me some idea of your speeds and feeds.

Kinda tough as we use different tooling, I use Seco and Iscar indexable drills as well as Kyrocera...I drill in and around recommended SFM and Feed. To bore, I reduce SFM by aprox 1/4-1/3...DOC aprox half the insert, increase Feed 10% to start and the chips tell me how to adjust.
 








 
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