MetalworkingFun Forum

My son is getting his FJ40 engine overhauled and he saved me the pistons and pins I think. If so, I'll send a couple to you when I get them. They are essentially 235 Chevy 6 cylinder parts so they should be solid and fairly large. I'll try to contact someone at the local diesel engine place and see what they can save for me.
Pistonium is also good for casting as well as wheelium.

(07-23-2012, 09:45 PM)NevadaBlue Wrote: [ -> ]Pistonium is also good for casting....

Two parts Chevy and one part Ford is the ideal alloy if I recall correctly, according to Burt Munro.....

Unfortunately the only thing I am set up to cast is lead alloys.

(07-23-2012, 09:45 PM)NevadaBlue Wrote: [ -> ]My son is getting his FJ40 engine overhauled and he saved me the pistons and pins I think. If so, I'll send a couple to you when I get them. They are essentially 235 Chevy 6 cylinder parts so they should be solid and fairly large. I'll try to contact someone at the local diesel engine place and see what they can save for me.
Pistonium is also good for casting as well as wheelium.

depends on the alloy thats in the pistons, most of them are cut from a bar of round stock and machined out. Some the alloy is way off out in left field due to the heat and pressure that they work in specially big construction equipment and truck engines

(07-23-2012, 10:58 PM)dallen Wrote: [ -> ]

(07-23-2012, 09:45 PM)NevadaBlue Wrote: [ -> ]My son is getting his FJ40 engine overhauled and he saved me the pistons and pins I think. If so, I'll send a couple to you when I get them. They are essentially 235 Chevy 6 cylinder parts so they should be solid and fairly large. I'll try to contact someone at the local diesel engine place and see what they can save for me.
Pistonium is also good for casting as well as wheelium.

depends on the alloy thats in the pistons, most of them are cut from a bar of round stock and machined out. Some the alloy is way off out in left field due to the heat and pressure that they work in specially big construction equipment and truck engines

Sorry Dallen,
It's actually really rare to find billet pistons, 90% or more are cast and the heavy duty stuff is almost exclusively forged, they do cut a lump off the end of a piece of barstock then heat it to around 400C drop it into a Cup shaped Die, then push the male die into it the male Die forms the inner cavity of the piston, from there they drill, bore and finish the wrist pin bore and then registering on the wrist pin the top and skirt are machined last,
Pistons with significant crown features use a complex shape in the Cup die, where simple crowned pistons use a flat base in the cup die and the features are machined.

Sorry to contradict but I actually made a piston forming press a few years back for a specialist race engine company and I thought the process might be of interest. Where you are right is in the alloy department, they are specialist materials for sure, in my home town the local speed shop was using all the old pistons out of the recon engine department in a local foundry to manufacture aftermarket manifolds, it was common knowledge that while they worked ok they just couldn't be polished as the alloy wouldn't hold a shine, but they didn't crack or anything nasty like that. Most people didn't know where the alloy was coming from I only found out years later when I was talking to the guy from the foundry that used to cast the manifolds, he told me "Old Cainy didn't want anyone to know what he was using for feedstock, that's why we used to cast em on the weekend"

When i was working in Alternate fuel R&D we used to do a dozen or more rebuilds on one or two big road diesels each year, and used to keep all pistons as a record of the testing work, as you can imagine after eight years we had a lot of big pistons, we would often use wrist pins as spacers and such but don't go looking for them as a source of machining stock, hard stuff unless normalised, so hard HSS won't even think about it, Carbide just scratches it but won't cut and ceramics only just allow a fine glowing red shaving, if the lathe in use is super rigid. I tried to make punches out of them and even normalised they were tough going, I ended up just buying the proper grade and left the wrist pins alone.

Best regards
Rick

(08-14-2012, 03:13 PM)Rickabilly Wrote: [ -> ]

(07-23-2012, 10:58 PM)dallen Wrote: [ -> ]

(07-23-2012, 09:45 PM)NevadaBlue Wrote: [ -> ]My son is getting his FJ40 engine overhauled and he saved me the pistons and pins I think. If so, I'll send a couple to you when I get them. They are essentially 235 Chevy 6 cylinder parts so they should be solid and fairly large. I'll try to contact someone at the local diesel engine place and see what they can save for me.
Pistonium is also good for casting as well as wheelium.

depends on the alloy thats in the pistons, most of them are cut from a bar of round stock and machined out. Some the alloy is way off out in left field due to the heat and pressure that they work in specially big construction equipment and truck engines

Sorry Dallen,
It's actually really rare to find billet pistons, 90% or more are cast and the heavy duty stuff is almost exclusively forged, they do cut a lump off the end of a piece of barstock then heat it to around 400C drop it into a Cup shaped Die, then push the male die into it the male Die forms the inner cavity of the piston, from there they drill, bore and finish the wrist pin bore and then registering on the wrist pin the top and skirt are machined last,
Pistons with significant crown features use a complex shape in the Cup die, where simple crowned pistons use a flat base in the cup die and the features are machined.

Sorry to contradict but I actually made a piston forming press a few years back for a specialist race engine company and I thought the process might be of interest. Where you are right is in the alloy department, they are specialist materials for sure, in my home town the local speed shop was using all the old pistons out of the recon engine department in a local foundry to manufacture aftermarket manifolds, it was common knowledge that while they worked ok they just couldn't be polished as the alloy wouldn't hold a shine, but they didn't crack or anything nasty like that. Most people didn't know where the alloy was coming from I only found out years later when I was talking to the guy from the foundry that used to cast the manifolds, he told me "Old Cainy didn't want anyone to know what he was using for feedstock, that's why we used to cast em on the weekend"

When i was working in Alternate fuel R&D we used to do a dozen or more rebuilds on one or two big road diesels each year, and used to keep all pistons as a record of the testing work, as you can imagine after eight years we had a lot of big pistons, we would often use wrist pins as spacers and such but don't go looking for them as a source of machining stock, hard stuff unless normalised, so hard HSS won't even think about it, Carbide just scratches it but won't cut and ceramics only just allow a fine glowing red shaving, if the lathe in use is super rigid. I tried to make punches out of them and even normalised they were tough going, I ended up just buying the proper grade and left the wrist pins alone.

Best regards
Rick

I can see your way for specialty pistons. I think the video is more in line with normal everyday pistons that don't have to make it around the race track.

But I may be wrong

http://www.bing.com/videos/search?q=how+...FORM=VIRE2

and yes wrist pins are hard, I hadn't planned on trying to turn them thou.

Interesting project, keep us updated on this.

(08-14-2012, 05:30 PM)dallen Wrote: [ -> ]

(08-14-2012, 03:13 PM)Rickabilly Wrote: [ -> ]

(07-23-2012, 10:58 PM)dallen Wrote: [ -> ]depends on the alloy thats in the pistons, most of them are cut from a bar of round stock and machined out. Some the alloy is way off out in left field due to the heat and pressure that they work in specially big construction equipment and truck engines

Sorry Dallen,
It's actually really rare to find billet pistons, 90% or more are cast and the heavy duty stuff is almost exclusively forged, they do cut a lump off the end of a piece of barstock then heat it to around 400C drop it into a Cup shaped Die, then push the male die into it the male Die forms the inner cavity of the piston, from there they drill, bore and finish the wrist pin bore and then registering on the wrist pin the top and skirt are machined last,...

Best regards
Rick

I can see your way for specialty pistons. I think the video is more in line with normal everyday pistons that don't have to make it around the race track.

But I may be wrong

http://www.bing.com/videos/search?q=how+...FORM=VIRE2

and yes wrist pins are hard, I hadn't planned on trying to turn them thou.

Not to be contrary but maybe I didn't understand this post. The process shown in that video is exactly what Rickabilly was talking about - forged pistons.

-Ron

Just to clarify;

Yes Ron the process in the post was exactly the process I described.

The only reason I chose to contradict Dallen in the first place, which is something I rarely do online, was that taking Billet machining as a "Normal process" for piston manufacture in context with the discussion that was taking place people might incorrectly influence folks to choose to use, or not to use pistons as raw materials for casting Which could lead to any number of issues. It was never my intention to offend in any way, I only post on any forums in order to share my accrued knowledge in order to help people acheive their goals in this case in "Fun Metal work"

But to further outline piston manufacturing processes, it's true that Pistons are manufactured by Casting, Forging and Billet machining, In that order I was given the following percentages when working on the forging press I don't know their origin but they are broadly in line with what I have seen in practice;

Casting is used for 90%+ of Petrol/Gasoline engined cars, they are cheap and cheerful to manufacture have suitable metallurgical grain structures and do not suffer from the heat expansion issues that affect Forged pistons.

Forging is used for most of the rest of the Car pistons and probably much more than 90% of the Pistons used in Diesel Engines (more like 99%), as Diesel engines require much heavier pistons than Petrol engined cars and also suffer from much greater stresses than all but very high performance petrol engines, Forged pistons require more piston to bore clearance than either cast or billet machined as a result of their "Thermal growth characteristics" which can cause them change shape a little more than the other two when heated, this I was taught, is as a result of the various stored stresses in the grain structures as a result of the forging, these grain structures are not entirely removed by normalising as this would ruin the strength benefit from forging.

Of the three processes Billet machining is by far the rarest method, as it is both much more expensive to do in numbers (and even a small car,truck or plane engine uses at least four) and the metalurgical results are less than satisfactory, with all of the important grain structures being cut at the most critical places(around the base of the wrist pin bosses). To my knowledge no current OEM uses billet machined pistons, and in the tearing down of hundreds if not thousands of OEM engines as a part of my R&D career I have not yet found a single billet machined piston. They are used in areas of motorsport where specific geometric properties require pistons to be manufactured to suit when no dies or patterns exist to cast or forge, JE pistons(One billet piston manufacturer) claims they get greater strength by billet machining but to my knowledge they have never backed this up with testing against an identical forged item, choosing to use FEA instead which didn't take grain structure into account assuming homogenius material properties instead.

Once again, with respect to the original context, "casting fodder" It is completely acceptable to use cast pistons as raw casting materials, as for the other two, I'm sure they melt and solidify, I suppose if you are just using scrap anyway they will be as good as anything but the materials used were not formulated with the specific intention of casting so should be used with caution. The reason I described Forging as opposed to casting was simply that the Deutz pistons in the original post are, I believe, forged items.

A further note being that cast pistons don't usually polish well, nor do things cast from using cast pistons as feed stock, but as this isn't easily measured please accept this single point is just a matter of opinion.

Best regards
Rick

Sorry for Hi jacking the thread,
Very sorry,
Rick

HIJACK? LOL, my threads can't be hijacked... I enjoyed the discussion. Yes, I believe the Deutz pistons are forged. I used them because I had saved them for so long that they demanded to be used. I haven't been able to work in my shop for a long time now, we had some medical emergencies and now I'm frantically getting ready for winter. Fall is in the air up here in the canyon. I'll get back to this one of these days.

Oh, the metal in those pistons is 'gummy'. It wasn't really friendly at all to this novice machinist, but I got them flattened out.