SAE Porting in Inconel

metalmadness · Sep 27, 2021

Good day,

Has anyone here got experience with O-ring boss porting using Inconel 718? Job coming up is going to require a bunch of SAE ports in this lovely material and was wondering what your thoughts are. My only experience using form ports is exactly zero. I assume a carbide tipped SAE form will cut the inco just fine but at an extremely slow speed. Use like a reamer, predrill, circle mill, port, thread mill. Job done. Except I assume tool wear will be a factor here. The holes themselves are pretty small, 7/16-20 SAE, 1/2-20 SAE, 5/16-24SAE.

How critical is the thread gaging for an SAE port? Are go/no-go gages the way to go here?

These are near-net complex forms that I would really like to not screw off on because they are expensive and have long lead times.

Thanks

DouglasJRizzo · Sep 27, 2021

Definitely use go/go gauges.
Watch the speeds, tools can get cooked easily.
The tool maker will tell you what to run at - stat at the low end and work up.
A rigid setup is a must.

TeachMePlease · Sep 27, 2021

DouglasJRizzo said:
Definitely use go/go gauges.
Watch the speeds, tools can get cooked easily.
The tool maker will tell you what to run at - stat at the low end and work up.
A rigid setup is a must.

Hmmm.... If I used go/go gages, I'd never have scrap!

Larry Dickman · Sep 27, 2021

TeachMePlease said:
Hmmm.... If I used go/go gages, I'd never have scrap!

but aren't go-go threads expected to strip?

Larry Dickman · Sep 27, 2021

I would prefer to turn a port in inconel rather than use a porting tool. What does the part look like?

metalmadness · Sep 27, 2021

Larry Dickman said:
I would prefer to turn a port in inconel rather than use a porting tool. What does the part look like?

These are 3D printed rocket engine parts so....yea not really fit for turning as the ports are located not along center. There may be some that could be turned but I am not sure about that quite yet.

DDoug · Sep 27, 2021

Larry Dickman said:
but aren't go-go threads expected to strip?

"Larry Rimshot Dickman".....

Mtndew · Sep 27, 2021

My experience with the porting tools is somewhat limited, but I'm pretty sure they thrive on a very stable setup, otherwise they tend to chatter.
Others may have had better luck with them but I don't like them. If it's a mill job, I'd look at profiling them if the form tool doesn't work like it should.

Bobw · Sep 27, 2021

Port tools suck..
The price of port tools sucks.
The geometry of port tools sucks.

Just thinking out loud.. I wonder if you would be money and time
ahead to have a carbide tool made that had the correct form, but
smaller, and with better geometry than a barn door.. And then
interpolate the form. kind of like threadmilling instead of tapping.

The threaded portion at the bottom can be brought to size with a drill,
and if you need the counter bore/flat at the top, you can do that with
an endmill.

TeachMePlease · Sep 27, 2021

Larry Dickman said:
but aren't go-go threads expected to strip?

Only if they drop out of college.

huskermcdoogle · Sep 27, 2021

I think fluting would be a challenge for an all in one. But if you were to drill the pilot hole and only have to do the chamfers I think you'd be fine.

IMHO, drill the hole, stay a chamfer distance short of the bottom, rough mill the counterbore with a small stock allowance, then use the port tool to finish it. The material at the bottom of the hole will provide stability for the tool using the drill point.

Larry Dickman · Sep 27, 2021

Bobw said:
Just thinking out loud.. I wonder if you would be money and time
ahead to have a carbide tool made that had the correct form, but
smaller, and with better geometry than a barn door.. And then
interpolate the form. kind of like threadmilling instead of tapping.

Actually, I have a customer who does this on hard shit, like D-2
They say it works great, plus you can do different size ports with the same tool

Zeuserdoo · Sep 27, 2021

I see a lot of guys here talking down on port tools. I've used them in Inconel with good results. When running a port tool, good runout, a rigid setup, and even stock removal are the keys to success. Follow the manufacturers recommendation for the speeds and feeds, and you should end up with a consistent, quality port every time.

metalmadness · Sep 27, 2021

Bobw said:
Port tools suck..
The price of port tools sucks.
The geometry of port tools sucks.

Just thinking out loud.. I wonder if you would be money and time
ahead to have a carbide tool made that had the correct form, but
smaller, and with better geometry than a barn door.. And then
interpolate the form. kind of like threadmilling instead of tapping.

The threaded portion at the bottom can be brought to size with a drill,
and if you need the counter bore/flat at the top, you can do that with
an endmill.

Sadly I have neither the time nor money to get a custom form tool ground. Though that would be ideal!

metalmadness · Sep 27, 2021

Zeuserdoo said:
I see a lot of guys here talking down on port tools. I've used them in Inconel with good results. When running a port tool, good runout, a rigid setup, and even stock removal are the keys to success. Follow the manufacturers recommendation for the speeds and feeds, and you should end up with a consistent, quality port every time.

I like to hear it. Have you any suggestions for setting up a recipe for success outside of speeds and feeds from the mfg? Like how much stock to leave for the porting operation?

metalmadness · Sep 27, 2021

huskermcdoogle said:
I think fluting would be a challenge for an all in one. But if you were to drill the pilot hole and only have to do the chamfers I think you'd be fine.

IMHO, drill the hole, stay a chamfer distance short of the bottom, rough mill the counterbore with a small stock allowance, then use the port tool to finish it. The material at the bottom of the hole will provide stability for the tool using the drill point.

This sounds like a good idea

Bobw · Sep 27, 2021

metalmadness said:
Sadly I have neither the time nor money to get a custom form tool ground. Though that would be ideal!

Sadly, looking at the prices of HSS port tools now on McMaster Carr. You might be money
ahead having a handful of customs made, and even paying for an expedite fee.

I swear they used to be like $50 for HSS and maybe $120 for the brazed carbide ones.
I think the most I paid was $450, but it was some odd ball F'd up port spec that only one
company had in stock, and it was brazed carbide, which I didn't need, since it was
30 holes in aluminum.

Zeuserdoo · Sep 27, 2021

metalmadness said:
I like to hear it. Have you any suggestions for setting up a recipe for success outside of speeds and feeds from the mfg? Like how much stock to leave for the porting operation?

Here you go. Inconel 625 AS4375-06 port.

Stock for finishing: Floors .004, Walls .007 (per side,) Thru bore drilled .006 under size.

Solid Carbide Port Tool AlTiN coated: SFM 112, feed 1.85 IPM

Rick Finsta · Sep 27, 2021

I have found the Scientific Cutting Tools brazed carbide units to be pretty economical, but there are inserted options out there as well that I've used. Only ever in aluminum or normal steels, though.

TeachMePlease · Sep 28, 2021

metalmadness said:
Sadly I have neither the time nor money to get a custom form tool ground. Though that would be ideal!

So, disclaimer, I've never even been in the same ROOM as an SAE port tool...

But based on the prices CarbideBob quoted above... I think you could get a handful of custom carbide ones for the same/less, and faster than you think. You'd need a good drawing with tolerances though.

People that could make them:

Schwanog: Probably the highest quality, but possibly the longest lead time.

GWS Toolgroup: Good quality, lead times vary with how big of a customer you are, and their work load.

MA Ford: Great quality, lead times can be all over the place, but they will expedite, for a fee.

MITGI: Fastest lead time, I get tools in a week or less when I REALLY need them, but usually 2 weeks is a standard lead time. Generally the lowest price. Their tools are good. Not Mikron or Schwanog quality GREAT... But really good, especially at their price:performance ratio.

SAE Porting in Inconel

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