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Air compressor piston- 6061?

G

Garwood

Diamond
Joined
Oct 10, 2009
Location
Oregon
Air compressor piston under 2" diameter. Any reason it would not work to machine from 6061 or 7075 bar?
 
Yeah, I forgot to say it's oil bath.

I want to change the ring land design to something more modern. It would be easier to make new pistons than modify old parts. This isn't for one, but hundreds of pistons.
 
Maybe the question would be better asked-

What would be the best suited for air compressor piston manufacturing aluminum alloy that is commonly available in barstock.
 
Garwood said:
This isn't for one, but hundreds of pistons.
Click to expand...
Probably easier to have a piston company make them, then you sell them then. Working with pistons is kind of a bitch, making them out of solid would be a pain, and your choice of materials is limited. I'm a do-it-yourselfer myself but still, sometimes it makes more sense to go to someone who is set up for it.
 
EmanuelGoldstein said:
Probably easier to have a piston company make them, then you sell them then. Working with pistons is kind of a bitch, making them out of solid would be a pain, and your choice of materials is limited. I'm a do-it-yourselfer myself but still, sometimes it makes more sense to go to someone who is set up for it.
Click to expand...

I could kind of see myself giving the same exact advice you just wrote there.

However, Being in the actual driver seat of this endeavor, do I utilize one of the CNC lathes that sits much of the time to blank out these pistons and if I don't, then WHY?

So where I'm at is the "why" part.

I get pistons are kinda complicated, but I would genuinely like to know what would stop me from making them from 6061 on a very accurate 2 axis Mori lathe followed by a couple ops on a VMC with a 4th?

Sounds like a fun and profitable project to me. Why won't it work/ what specifically makes it not worth it?

These are little, simple pistons.
 
Maybe my google-fu is weak, but I can't find a USA based manufacturer of pistons that isn't specializing in forged racing parts.
 
Garwood said:
So where I'm at is the "why" part.

I get pistons are kinda complicated, but I would genuinely like to know what would stop me from making them from 6061 on a very accurate 2 axis Mori lathe followed by a couple ops on a VMC with a 4th?
Click to expand...
Are the skirts cammed ? Even if they are, and you're set on it, there's Van Norman piston grinders out there cheap, you could do that as a finish op.

6061 sounds better to me for material, 7075 has a bad habit of stress cracking and so on ...

Alternatively, perhaps you could buy cast blanks from a piston place and save yourself a lot of mill time, plus get a better alloy.

Or for that matter, have them cast yourself, there's still foundries on the west coast that do aluminum.
 
Seems to me that the silicon in the aluminum pistons is going to polish the cast iron sleeve the same way the silicon in your aluminum engine bearings does the same to the hardened crankshaft.

However, the little bit of googling I just did returns results to the effect that silicon is added to reduce the piston's thermal expansion rate. not to polish the cylinder walls. i would be concerned about galling...


a certain oil-less compressor manufacturer seems to use something very similar to turcite for both the rings and a big sleeve that surrounds the piston skirt.

The aluminum piston probably never touches the cylinder wall.
SCHULZ OILLESS AIR COMPRESSOR PUMP MSV 6- 1 HP- 6 CFM OILLESS – SWING TECHNOLOGY LLC
 
Any chance that piston diameter is already being made for something else. 2" diameter would probably be a two cycle engine so maybe not.
Bill D
 
If its going on a 4th for second op, program your cam and taper in and cut it with a ball mill , beings on a compressor probably won’t need much of either, just guessing


When I find it I don’t need it
When I need it I can’t find it!
 
Turbowerks said:
If its going on a 4th for second op, program your cam and taper in and cut it with a ball mill , beings on a compressor probably won’t need much of either, just guessing
Click to expand...

I don't recall any compressor pistons having much more than .004" drop @45 from the major OD from my (too much) time working at a place making pistons for a living. In regard to the material, they were never made out of anything other than 2618 or 4032 during my time there. 6061 was only ever used for non-piston things.

One thing that that no one else has mentioned is to make sure that the flatness/angle of the ring grooves is close to 0 with any deflection pointed toward the crown.
 
SumiSpy said:
I don't recall any compressor pistons having much more than .004" drop @45 from the major OD from my (too much) time working at a place making pistons for a living. In regard to the material, they were never made out of anything other than 2618 or 4032 during my time there. 6061 was only ever used for non-piston things.

One thing that that no one else has mentioned is to make sure that the flatness/angle of the ring grooves is close to 0 with any deflection pointed toward the crown.
Click to expand...

Those are the alloys I’m familiar with for pistons too. Mad some billet compressors turbo wheels out of 2618 forgings and 7075 material also. A Few places i know of machine ‘billet’ pistons for pulling motors because of forging are not available in the size but no one is saying what material is used. My big compressor has iron pistons in the high pressure side with way too thick of rings for my liking but it has run thousands of hrs with no trouble probably 10s of thousands of hrs.


When I find it I don’t need it
When I need it I can’t find it!
 
Never checked one- are they cam ground or not? Now I'm going to have to go out and check the spare pistons for my compressor that I fished out of my neighbor's garbage when they forgot to check the oil in theirs. Not sure what you are up to with your project, but you MIGHT give Egge a call and see if they had castings they might sell you. Yours are kinda small but...…….
 
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