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125-250 Surface Finish, Valve-Flange

bcurtis

Plastic
Joined
Jun 23, 2022
I am quoting a job for a couple valve-flanges that have a callout for a 125-250 Surface finish on a the bottom surface of a face groove.
Any recommendations on tools, or feeds in order to hold that finish (We will be running them on a swiss style lathe)?
- We are running an aluminum part as well as a couple Brass parts.
 
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Zeuserdoo

Aluminum
Joined
Aug 31, 2015
Location
The Moridor
How wide is the groove? I've made parts that specified a 250 minimum finish on an O.D. and I just ran the feed fast to leave a rough finish. That's going to be a lot harder in a face groove.
 

bcurtis

Plastic
Joined
Jun 23, 2022
How wide is the groove? I've made parts that specified a 250 minimum finish on an O.D. and I just ran the feed fast to leave a rough finish. That's going to be a lot harder in a face groove.
Face groove is approximately .170" wide.
 

TeachMePlease

Diamond
Joined
Feb 11, 2014
Location
FL
Yeah... How wide is this groove? Swiss lathe says it's a small part... How wide, how deep, and how will you/the customer check it?
 

eKretz

Diamond; Mod Squad
Joined
Mar 27, 2005
Location
Northwest Indiana, USA
What nose radius is the tool you plan on using? The nose radius will determine the ballpark feedrate you need to hit your finish. Some valve manufacturers want a phonographic (turned spiral, generated by a normal facing cut) finish, some specify concentric grooves (so you'd have to plunge the tool, retract, move over, plunge, retract, move over, etc.)
 

Zeuserdoo

Aluminum
Joined
Aug 31, 2015
Location
The Moridor
Can you post a sketch or drawing of the feature? That would help us out a lot. I do have a couple of ideas depending on the depth and sides of the groove.
 

latheman78

Cast Iron
Joined
May 28, 2022
Location
Southern Ca Mtns.
Since it is only .170 wide it might be hard to get that finish from feeding. I wonder if you could just chatter it in by making a high RPM finish pass at slow feed?
 

Booze Daily

Titanium
Joined
Sep 18, 2015
Location
Ohio
If you have live milling you could trepan it in with a face groover then buzz around the bottom with an endmill to rough it up.
 

guythatbrews

Cast Iron
Joined
Dec 14, 2017
Location
MO, USA
If the surface finish lay is not specified concentric maybe you could use a full radius trepan tool and simply face for a spiral finish. Maybe you have a max corner radius requirement you have to meet. Find a trepan tool with smaller radius, calculate federate for finish, and I like to test cut in engine lathe with the same material and check the finish. Fine tune from there. Unless you have a skidless surface tester and even then then I'll bet .170 is not wide enough to check.
 

guythatbrews

Cast Iron
Joined
Dec 14, 2017
Location
MO, USA
This would be very difficult to do with a straight in plunge cut. Maybe a tool with the nose profile ground to a coarse finish.
It is. Have a customer that requires a 63-125. They have two options to produce the finish. One is a special forming tool with a wavy finish. The wave features are so small I never have found anyone to make it. Wire edm wire to big. Sinker they cant make the electrode. The customer doesn't have a source. Do I default to spiral finish with 1/64 TNR.
 

bcurtis

Plastic
Joined
Jun 23, 2022
If the surface finish lay is not specified concentric maybe you could use a full radius trepan tool and simply face for a spiral finish. Maybe you have a max corner radius requirement you have to meet. Find a trepan tool with smaller radius, calculate federate for finish, and I like to test cut in engine lathe with the same material and check the finish. Fine tune from there. Unless you have a skidless surface tester and even then then I'll bet .170 is not wide enough to check.
Surface finish lay is not specified. I believe our surface tester can check within that .170.
 

guythatbrews

Cast Iron
Joined
Dec 14, 2017
Location
MO, USA
I guess you could try dressing a wheel at different rates and plunge grinding tool face on surface grinder, making test cut and checking finish. Iterate until success.
 

guythatbrews

Cast Iron
Joined
Dec 14, 2017
Location
MO, USA
I guess you could try dressing a wheel at different rates and plunge grinding tool face on surface grinder, making test cut and checking finish. Iterate until success.
If you do this the tool will need to be full width. Since parts are brass and al use an uncoated tool don't have to worry about coating.

I think the full radius trepan is your best bet, as long as max allowable inside rad is not crazy small. Maybe rough sides and bottom with something more robust.
 

eKretz

Diamond; Mod Squad
Joined
Mar 27, 2005
Location
Northwest Indiana, USA
If you do this the tool will need to be full width. Since parts are brass and al use an uncoated tool don't have to worry about coating.

I think the full radius trepan is your best bet, as long as max allowable inside rad is not crazy small. Maybe rough sides and bottom with something more robust.

It looks like the radius is too small for that. Another alternative I have used in a pinch is to take a face grooving tool that is say 1/16" wide and grind the center of the nose hollow so it effectively contacts the diameter or face being turned only on the corners of the insert. Grind the inside corners of the hollow to a sharp point or radius as suits, and run an appropriate feed to get the desired finish. The profile ground nose would be quickest per part, but the most work to get figured out. Would be worth it maybe for a high number of parts on a CNC if it could be standardized and was repeatable. As always, more than one way to skin die Katze.
 

Conrad Hoffman

Titanium
Joined
May 10, 2009
Location
Canandaigua, NY, USA
The cutoff length for that surface finish is about 0.1 inch, but you have to assess over about 5X that number. IMO, it's yet another case of a generic surface finish callout with not enough surface to properly make the measurement. Regardless, I'm thinking a plunge tool with the desired finish ground on the cutting edge. Maybe via EDM or just a touch on the right grinding wheel running at slow speed.
 








 
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