THROUGH COOLANT BORING BARS

[INTERPOLATE]

Greetings group..
I would like to rig up a small coolant tank/pump system that can supply my Kennametal boring bar A12SCLPR3 (.750 dia bar, CPGM 32.52, 1/8-27NPT hookup)
Will the regular pumps found in a AIRGAS catalog work? Or does it have to be a special high pressure type unit?
Thanks,
JD

[spope14]

I o not kno about the "airgas" pump, but I have a few through coolant bars, and i use my little Emco coolant pumps wih some attachments to put the coolant through. I would not do ID blind bottom threading without coolant washing out the cut anymore. Not high presure by any means, just enough to put the coolant in and llow for a 'wash out'. My old J&L (yes this one again) has a lo pressure coolant system, an it works just ine with coolnt fed drills, bore bars, such on and so forth. I probably get a 2" spray out of the ends on a good day.......

[Tony]

sidebar: excuse my inexperience, but i've always been told to never use coolant with carbide (either solid, brazed, or insert style) .. in fact i never use it for anything other than HSS (be it for lathe tool bits or drilling).

though i've seen the through coolant bars in catalogs.

what am i missing here?
-tony

[tattoomike68]

knucklehead

you can use coolant on carbide just dont get the carbide super hot then hit it with coolant or it will cause micro cracks and make the carbide like a busted car winshield.

so what I mean is use coolant or dont, but dont cool off cabide fast and shock it.(a blast of air wont hurt to cool a tool)

[This message has been edited by tattoomike68 (edited 09-22-2004).]

[Tony]

don't mean to hijack the thread buuuuut...

other than the situation JD is asking about (and maybe other highpressure CNC work), when would you want to flood a carbide (lets say, Insert) tool?

my lathe tops out at about 1800rpm. my carbide tooling does get hot, but always seems to perform well. tool life seems ok, too.

not playing dumb here, but genuinely curious.

-tony

[spope14]

I flood coolant on carbides when doing CNC lathe work, and the conditions allow for this to happen such as coolant "splash control (guarding)". The recovery of coolant is also important in considering.

I have "flooded" on my manual lathes, items like Stainless, 41 series, and such where heat can be an enemy on the materials. Also aluminums where built up edge on tools can be an issue when I need to spin the RPM's up there. There are also the "chip control" issues where coolant comes in handy such as threading, boring, cutoff, grooving, and form tooling. Many a factor, but for general turning on my manual lathes (low volume work), I do not flood as a rule because the mess becomes an issue. However, flooded carbides, from my experience, have a longer tool life, and when production situations warrant, I do this. Also can give more "consistant" surface finishes over a long run of parts.

I try to flood in boring, for the chip removal aspects, and the consistant surface finish resulting from chip removal. The main factor here is "chip re-cutting", which can be a killer on carbides, espeially with the stainless, 41 series, and exotics, where the chip has slight work hardening already, and re-cutting can chip the tool or mark the work.

Heat control on the work itself can be a factor in "tight work". A cooled work situation compared to a "heated work situation" can lead to more accurate measuring throughout the process, and better and more consistant tolerance control.

On milling, I use CNC "tool room" type mills, which have minimal guarding, and hand change tool systems. I also run machining centers off site, which the guarding allows for flooding all the time, but the tool room mills, and even manual milling will be addressesd here. The issues I have are chip removal, surface finish consistancy, and chip re-cutting. On surfacing, I have tangency issues with the tool, where the actual cutting surface is rather small at the tangent point of the tool, thus the heat more concentrated. Same with engraving with my small point tools - I always flood or use something there... Pocketing, chips have to get right out of there, or you beat the heck out of your edges and bottom. Edges, if you flood, you keep the cutter clean of possible chips running around the cutter and re-cutting, same with facing. Flooding can, in many circumstances, allow for more speed and feed in the operation

However, as good as flooding may be, I still try to minimize my coolant uses, for you do have to clean it up, it does have its issues in a low volume shop or home shop such as disposal, storage, and disposal.

On a side note: Ceramics and Cerments do NOT like coolant from my experience, though you need to read the literature for each, for some are now working through and with this issue. I actually use some ceramics in my school shop in boring. I have seen "compressed air" used on these cutters to blow out the chips. I use compressed air choked down to 15# for boring when I bore with my ceramics. I love ceramics for Horizontal machining centers where gravity is your friend when milling pockets and surfaces...

Just notes from experience, and compressed at that. What works for me. Each person has different views, and this is the great thing about this board, for in machining, this is a CRAFT, and each Craftsman has their own ways, thus the reason we love this stuff.



[This message has been edited by spope14 (edited 09-23-2004).]

[spope14]

Adt'l note for interpolate: I have a Kennematal bar for threading with the same end set-up. I made a little adaptor to go on my coolant end on my Clausings and emcos, which run low volume coolant. Works for me!!!!!

[C. Tate]

If you are running on a conventional machine go dry and pump a small amount of air to clear chips. The tool will function just fine without coolant. If you have the chip load and cutting speed at optimal levels you do not need coolant because 90 percent of the heat is absorbed by the chip.

CT

[Paul Alciatore]

I'm not an expert on carbide or coolants. I do know that coolant is generally applied two ways: CONTINOUSLY as in a flood or mist cooling setup and intermittently (manually) with a brush or hand sprayer as I frequently do in my small shop. From what I've read, I suspect that the manual method is very bad for carbide because it is not continous. The tool gets very hot and then a dab or squirt of coolant is applied and it is instantly cooled down, creating large stresses and cracks. Apparently HSS can take this shock a lot better than carbide.

With flood or mist application of coolant, the coolant flow is started BEFORE the cutting starts and it is constantly hitting the tool while its cutting so the tool never has the chance to get really hot. No thermal shock and no cracks.

The old timers can correct me on this but that's what I have understood.

I don't think you will find much tooling with internal coolant channels in an Enco, MSC, KBC type catalog (although occasionally there is some). You will have to go to the manufacturer's catalogs. If you have a good tool and die supplier in your area check with them. Be prepaired for big $$$s.

Paul A.

<font face="Verdana, Arial" size="2">Originally posted by knucklehead:
sidebar: excuse my inexperience, but i've always been told to never use coolant with carbide (either solid, brazed, or insert style) .. in fact i never use it for anything other than HSS (be it for lathe tool bits or drilling).

though i've seen the through coolant bars in catalogs.

what am i missing here?
-tony</font>

[bspooh]

It depends on what grade of insert you are using...some coatings work better under coolant, while other types work better when the insert gets hot...

Generally speaking though, milling means no coolant and turning means use coolant..Turning is continuous, while milling is intermittant...

brent