Inconel 718 Drilling Speeds and Feeds Hss
- #1
Im going to be machining some 718 inconel with a hardness rating of 415 HBW.I am hoping to get advise on spindle speed and IPR using 3/8 coolant feed carbide drills. The holes will be 2.51 deep and I am hoping not to accidently work harden this expensive material. The machine I will be using is a Mori Seiki SL-150 SMC with Y axis so center line issues should not be a problem but I have not drilled alot of inconel before so any advise or suggestions would be much appreciated. Thanks
- #2
Drilling inconel can be a bitch. Are you drilling bar stock or castings? There's a huge difference.
What kind of carbide drills are you planning to break, i mean use? If they're not the right style Gurhing, you wasted your money.
Second choice for drills are the OSG VPH powdered metal drills. They work awesome, althoiugh they are not as fast as Gurhing carbide drills, they're also about 1/6 the price.
- #3
Drilling inconel can be a bitch. Are you drilling bar stock or castings? There's a huge difference.
What kind of carbide drills are you planning to break, i mean use? If they're not the right style Gurhing, you wasted your money.
Second choice for drills are the OSG VPH powdered metal drills. They work awesome, althoiugh they are not as fast as Gurhing carbide drills, they're also about 1/6 the price.
I think the OSG would be great to help understand how to drill Inconel.
- #4
Gurhing FTW!!!!!!!!!!
i good friend gets thousands of holes per drill with the right setup.
no spot
no peck
great TSC
around .002"/rev
not so sure about that depth
- #5
IMO, get ya a drop and start drilling some holes manually to get a feel for Inco. It can be a bear, but once you've got the doo's and don'ts figured out it's not a nightmare, it's still work but not pull hour hair out type of work. Castings and bar do make a world of difference. Guhring is King in my book, but OSG is also great and offer a little more info, Guhring just thinks everyone is born a genius, but I really like their tooling$$
Robert
- #6
The material is bar stock, the drills are Kennametal, nickel alloy specific according to the material specialist at MSC. They reccomand 70-80 SFM witch I believe to be around 450 RPM. The feed around .0015/.003 I.P.R.. Now that I have their reccomendations do these speeds and feeds sound appropriate?
Also does a 10% coolant concentration level sound high enough to yall.
Thank you very much for the advise.
- #7
Sorry for a dumb question but what does TSC stand for?
- #8
"TSC"...that shit crazy!!! lol i think it means "theoretical sharp corner" but i could be wrong
- #9
Through spindle coolant
- #10
yeah, might have guessed wrong.
- #11
"great thru spindle coolant"???? why is it great in inconel and not say aluminum? round here i call it coolant thru spindle...or waterdrill
- #12
exactly! nobody not say aluminum.
- #13
not sure what your getting at...is inconel better for waterdrills than aluminum????i thinks not
- #14
The drills do have thru coolant to the cutting end but my Mori only has 150 P.S.I.. They are static mounted, I could put in the live tooling but at 70-80 SFM or around 450 RPM I dont think my live tools would be good at such a slow RPM. What say you? This 718 inconel is pretty damn hard compared to aluminum and work hardening is a big concern. It would be comparable to hastalloy to my understanding, again thanks for any advise about this specific material
- #15
Without High Pressure coolant, I would start at 450RPM/ .002 IPR... On a drop (as suggested earlier), and find the sweet spot. Don't mess around w/ the live tools.
Chazsani
- #16
How many you have to do?
If it were me I would pay someone to gun drill them.
Might be an option if you have too many troubles?
What are you using for coolant?
- #17
Gurhing FTW!!!!!!!!!!
i good friend gets thousands of holes per drill with the right setup.
no spot
no peck
great TSC
around .002"/rev
not so sure about that depth
This. At that depth...good luck. Your learning curve will be similar in shape to a skyscraper. I know mine was.
- #18
My chart says 180sfm @. 008 for guring 0.375( i run this stuff weekley) but i reccomend 120 at 0.003. I really wouldnt worry too much about worry too much about work hardening. Just watch your chip. Rule of thumb is 50% of your stainless steel speeds. If you start there, and watch your chip, youll be fine
- #19
For a 3/8" diameter drill...70-80 sfm is 712-814 rpm. Since you have a lower pressure you may want to drop down to about 60 sfm (610 rpm). I would stick between .002-.003 ipr on the feed.
I have not run 718 inconel but I do a lot of 600, 625, 825, and Hastaloy C-276. The 625 and Hastaloy are closest to 718 in machinability.
For my CJT and Titex drills I run around 80 sfm and a feed multiplier of .006-.007 (take this constant times the drill diameter to get feed rate in ipr).
At the depth you are going I'd add a few pecks that get progressively shallower with slight dwells at the end of each cut (just .1 sec to complete the cut before rapid back). Some people may respond and say "DON'T DWELL BECAUSE YOU'LL WORK HARDEN!" Well, I do it constantly...but just .1 sec to complete the rev and cut away the chip before backing out. At 415 HBW your material is already pretty hard for Inconel. I'm guessing it's in a strain hardened state (hasn't been annealed after the cold drawing of the bar stock).
I'd do something like this:
X0 Z.5
Z.1
G1 Z-.1 F.0015
Z-1.15 F.0025
G4 X.1
G0 Z.1
Z-1.13
G1 Z-1.9 F.0025
G4 X.1
G0 Z.1
Z-1.88
G1 Z-2.51 F.0025
G4 X.1
G0 Z.5
The reduced feed on entry just makes sure it gets a chance to be on center. You can add a spot before this drill but only make it a small dimple....do not spot all the way to the drill diameter...the corners of the carbide drill don't like that.
This is what works for me...not saying it will for you. I've been running these nickel based alloys over 18 years on several lathe types with a variety of pressures and coolants (including oil).
- #20
MKD is simply saying no one ever said coolant thru drills are bad for Aluminum. Since your location is stated as "north of Bean town" I have no clue why you call them waterdrills, you could be from Mars. Most folks on this board use catalog nomenclatures for ease of understanding, find me an ad that calls it that... didn't think so. Coolant thru is integral for aggressive feeds (which it is in Inco), also integral for no peck drilling.
OP, I think Bradley is pretty close, I would not spot, I would not peck, UNTIL shit goes sideways, figuratively or literally. My best advice I already posted but I will add make sure you have plenty of extra bar, you are going to make some scrap I promise, and bust some drills.
Robert
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Source: https://www.practicalmachinist.com/vb/cnc-machining/advise-drilling-718-inconel-315457/
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