4032 aluminum drops?

Terry Keeley · Jun 12, 2021

Looking for a small amount (1-2') 1 1/2" 4032 round bar. Will take square, hex, plate etc. if that's all there is.

No luck anywhere, tried Speedy, On-line metals, McMaster and general google search.

Any ideas?

Rick Finsta · Jun 12, 2021

That is an alloy used in forgings AFAIK. I've never seen it outside of things like pistons. Even then, it is used in racing applications mostly due to its high expansion with heat relative to 2XXX series.

Maybe call Diamond or CP/Carrillo?

Terry Keeley · Jun 13, 2021

Rick Finsta said:
That is an alloy used in forgings AFAIK. I've never seen it outside of things like pistons. Even then, it is used in racing applications mostly due to its high expansion with heat relative to 2XXX series.

Maybe call Diamond or CP/Carrillo?

Thanks, I see it listed in round bar, just 12' lengths:

4032-T6, T651 Aluminum Round Bar - A & C Metals & Sawing, Inc.

dian · Jun 13, 2021

i wonder how such a high silicon alloy machines. what is it for?

Terry Keeley · Jun 13, 2021

dian said:
i wonder how such a high silicon alloy machines. what is it for?

It's for cylinder heads for my model boat engines, supposed to cut OK.

It conducts heat very well and matches the thermal expansion of the brass liners.

dian · Jun 13, 2021

makes sence, exept the liners might run cooler.

Sidebite · Jun 13, 2021

About 25 years ago I had some pistons made from 4032 for an experimental opposed piston diesel. I got the stock from Wiseco Pistons. It was the raw extruded bar they make forging blanks from. The machinist who did the fabrication said it machined like "chewing gum full of rocks" and it was hard to get a good surface finish. about 10 years later, I was working for a piston manufacturer and we used forgings from 4032 for the lower performance products, and 2618 for the higher end applications. After forging and heat treating, the 4032 machined quite nicely on a Takisawa CNC using PCD tooling for the grooves and skirts. Nice little chips that cleared the work. The 2618 would often get big stringy birds nests if you weren't careful. Surface finish was still better on the 2618, but the 4032 was quite acceptable.
I almost forgot: Occasionally at the piston factory, we would make prototype or short run custom pistons out of "pancake" forgings. These were forged and heat treated slugs, but had no forged in features. They were just big hockey pucks of Al. If you can find a piston mfg. or forging house to sell you a few of those, it will be much better to machine and have better properties than the raw bar stock.

steve-l · Jun 14, 2021

Rick Finsta said:
That is an alloy used in forgings AFAIK. I've never seen it outside of things like pistons. Even then, it is used in racing applications mostly due to its high expansion with heat relative to 2XXX series.

Maybe call Diamond or CP/Carrillo?

Rick, you have the properties backwards AL4032 has a smaller expansion coefficient than AL2618. AL4032 is a super eutectic alloy that allows tighter piston to wall clearances than AL2618, but AL4032's strength falls off rapidly above 300 C temperature in comparison to AL2618. AL2618, on the other hand, has superior cooling capability because of the copper in the alloy and greater strength. You may also note that AL2618 was developed by Roll Royce during WWII for pistons in the reciprocating Aero engines.

Al4032 is a superior piston material for limited duty engines, think emissions. AL2618, on the hand, is still the preferred material for high output/ high duty cycle applications. Although there are even better aluminum composite alloys for pistons, these alloys are yet not allowed by the regulations in most of the racing organizations because of cost.

steve-l · Jun 14, 2021

Sidebite said:
About 25 years ago I had some pistons made from 4032 for an experimental opposed piston diesel. I got the stock from Wiseco Pistons. It was the raw extruded bar they make forging blanks from. The machinist who did the fabrication said it machined like "chewing gum full of rocks" and it was hard to get a good surface finish. about 10 years later, I was working for a piston manufacturer and we used forgings from 4032 for the lower performance products, and 2618 for the higher end applications. After forging and heat treating, the 4032 machined quite nicely on a Takisawa CNC using PCD tooling for the grooves and skirts. Nice little chips that cleared the work. The 2618 would often get big stringy birds nests if you weren't careful. Surface finish was still better on the 2618, but the 4032 was quite acceptable.
I almost forgot: Occasionally at the piston factory, we would make prototype or short run custom pistons out of "pancake" forgings. These were forged and heat treated slugs, but had no forged in features. They were just big hockey pucks of Al. If you can find a piston mfg. or forging house to sell you a few of those, it will be much better to machine and have better properties than the raw bar stock.

You are correct and I very much like the machinist's description of machining AL4032. It needs to be T6 before you machine it first. Keep in mind that AL4032 is super Eutectic, that means there is more silicon in the alloy that can stay in even natural solution. Hence the accuracy of the machinist's description. My point is alloy quality will be all over the place.

Rick Finsta · Jun 15, 2021

steve-l said:
Rick, you have the properties backwards AL4032 has a smaller expansion coefficient than AL2618. AL4032 is a super eutectic alloy that allows tighter piston to wall clearances than AL2618, but AL4032's strength falls off rapidly above 300 C temperature in comparison to AL2618. AL2618, on the other hand, has superior cooling capability because of the copper in the alloy and greater strength. You may also note that AL2618 was developed by Roll Royce during WWII for pistons in the reciprocating Aero engines.

Al4032 is a superior piston material for limited duty engines, think emissions. AL2618, on the hand, is still the preferred material for high output/ high duty cycle applications. Although there are even better aluminum composite alloys for pistons, these alloys are yet not allowed by the regulations in most of the racing organizations because of cost.

Duh. Thanks for correcting me. I run 4032 in NA applications under 850hp or so but I think my current CPs are 2618 forgings and meant for about 1600hp or so.

steve-l · Jun 15, 2021

Rick Finsta said:
Duh. Thanks for correcting me. I run 4032 in NA applications under 850hp or so but I think my current CPs are 2618 forgings and meant for about 1600hp or so.

Rick, one of the problems in the US is the availability of modern design, light weight and high strength forgings. This is especially true if your bore size strays too far off 4.00 inches. CP as well as other companies will make you what you want out of billet no problem, but not in a forging unless you are seriously lucky. Forging dies are very expensive, hence their scarcity. You will find very good forging choices in Europe, specifically Austria, Italy and the UK, but the firms that own these dies have healthy minimum orders. I have had super luck in custom pistons with Pistal in Italy. Their minimum order is four for a one off piston design and they have a good selection of forgings. They also offer all the hi-tech features like DLC pins, hard anodized ring lands and anti-friction skirt coatings.

Milland · Jun 15, 2021

steve-l said:
Rick, one of the problems in the US is the availability of modern design, light weight and high strength forgings. This is especially true if your bore size strays too far off 4.00 inches. CP as well as other companies will make you what you want out of billet no problem, but not in a forging unless you are seriously lucky. Forging dies are very expensive, hence their scarcity. You will find very good forging choices in Europe, specifically Austria, Italy and the UK, but the firms that own these dies have healthy minimum orders. I have had super luck in custom pistons with Pistal in Italy. Their minimum order is four for a one off piston design and they have a good selection of forgings. They also offer all the hi-tech features like DLC pins, hard anodized ring lands and anti-friction skirt coatings.

If this is true, I fear for the US if we ever get back into a large conventional war. Forgings are critical for mass manufacture, and while we still have a number of large forges, if we're low on small ones that'll be a real bottleneck.

steve-l · Jun 15, 2021

Milland said:
If this is true, I fear for the US if we ever get back into a large conventional war. Forgings are critical for mass manufacture, and while we still have a number of large forges, if we're low on small ones that'll be a real bottleneck.

I'm not an expert on why these modern forging dies are not available, I suspect it is just the economy of scale. I suspect the number of forges is not the issue. Hot Rod/racing piston demand is relatively low in relation to OEM mass production. The bigger reason is the American public's reluctance to embrace 4 valve/ small displacement engines like the rest of the world has.

dian · Jun 16, 2021

you sound critical concerning the "reluctance". imo its well founded. (→kiss).

steve-l · Jun 16, 2021

dian said:
you sound critical concerning the "reluctance". imo its well founded. (→kiss).

Not really, it's a concept thing. Personally I really like big motors going slow. I like no noise torque. It pleases me, but that comes at a cost in fuel economy. At the moment, in Europe, E5 gasoline is running almost 2 Euros a liter. That's about $9.20 a US Gallon.

BT Fabrication · Jun 16, 2021

in ontario, try out metal supermarkets. they can probably get it for you.

also a piston manufacturer here in woodstock, try to call them and ask?

Terry Keeley · Jun 16, 2021

BT Fabrication said:
in ontario, try out metal supermarkets. they can probably get it for you.

also a piston manufacturer here in woodstock, try to call them and ask?

Tried Metal Supermarkets and Mckinnon, no luck.

Doubt they'd have any material, prolly just an outlet:

Wiseco Piston Canada - 948 Keyes Dr, Woodstock, ON N4V 1C2 | Websites.ca

Rick Finsta · Jun 16, 2021

steve-l said:
Rick, one of the problems in the US is the availability of modern design, light weight and high strength forgings. This is especially true if your bore size strays too far off 4.00 inches. CP as well as other companies will make you what you want out of billet no problem, but not in a forging unless you are seriously lucky. Forging dies are very expensive, hence their scarcity. You will find very good forging choices in Europe, specifically Austria, Italy and the UK, but the firms that own these dies have healthy minimum orders. I have had super luck in custom pistons with Pistal in Italy. Their minimum order is four for a one off piston design and they have a good selection of forgings. They also offer all the hi-tech features like DLC pins, hard anodized ring lands and anti-friction skirt coatings.

Yeah, CP was able to fit my customs into a forging they already had. It helped that it is an Oldsmobile, so I had plenty of compression height to work with to get the ring pack and pin in the right place, and I always target the 4.125-4.185" bore range to get into the common pistons for a huge number of race engines out there. Not too worried about weight, more worried about the pin bore strength. Motor is a <7000rpm twin turbo so the worries about rod stress at TDC exhaust are there, but not to the same degree as an NA motor. Especially with the low rpm power band (peak power should be around 6600-6800rpm).

Thread fully derailed LOL.

4032 aluminum drops?

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Titanium

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