Raw Cast Iron & Aluminum costs (casting)

I’m curious if you guys know of any online resources where I can make general comparisons between material costs. Currently, I’m looking for Aluminum and Cast Iron - not the process costs, but just the cost of the materials themselves.

Thanks in advance for anything you can offer.

Not sure about casting, but any local steel/metal supplier in your area should be able to provide you with a cost for the two materials in some form (i.e. sheet, extrusion, bar, etc.) Generally speaking, steel is cheaper than aluminum. But it all depends on the alloy and heat treatment. Cast aluminum (at least in the art world) is usually very soft stuff, so it’s cheaper than 6000 series for example.

Not sure if you want to go as far back in the supply chain as checking out Alcoa… if you do, be prepared for digging through some cumbersome sites.

As far as relative cost is concerned (as opposed to the absolute you could get from a front-end material supplier), I typically just go to mcmaster, find two sheets of material of same finish and size, and take my numbers from there. It’s not perfect, but it’s good to get a general grasp on cost.

Looks like aluminum is trading at $1.15/pound and iron is at $0.33/pound.

Don’t know the difference in casting costs, calling a foundry will give you that answer. And of course, shipping aluminum will be much less than the iron.

Not necessarily… often times dedicated (or even shared) shipping loads, are priced on volume and not weight.

Correct.

I wrote in haste. Depending on several factors, volumetric weight and timing can trump actual weight.

If volumes are very low (like one or two pieces), artists often go to scrap yards for raw material… very cheap, but not the cleanest or most pure mix of metals. For that a quick call to a local yard will give you an idea of the cost.

My favorite part about scrap yards, they weigh your car on the way in and again on the way out to make your bill

Thanks for the advice all. I won’t be needing actual aluminum. I might be designing a piano for my BFA project, and I’m trying to find out if it’s viable to replace the cast iron frame (the gaudy, gold-painted thing inside the case) with an aluminum one.

I guess now all I need to know is how they compare in terms of strength (since a piano’s strings have many tons of tension). Off to google!

Whoa… I’d be hesitant to change that to aluminum, and casting something like that will likely be tens of THOUSANDS of dollars.

For reference on piano building, you should watch this movie. It’s very well done.

Thanks for the link Nurb. I’ve done a good amount of research already, but this looks like an awesome resource that I’ll definitely pick up.


Although I haven’t picked a design story to pursue, one that I found compelling was an ultralight piano. When you say tens of thousands of dollars, do you mean material costs per part? or do you mean mold costs? I assumed that it might be 2-3 times more (like the price quoted above), but was planning on offseting that with other improvements.

In 1949 and 1950, Alcoa produced about 50,000 aluminum piano frames for Winter & Company. I assumed since it was viable then, it would be viable now…?

EDIT: here’s a pic.
DSC01720.jpg

Is iron used for strength or is the mass needed for the correct sound?

I guess I thought you were going to actually produce a finished piece… since it seems like you aren’t:

I’m sure you could make it out of aluminum, but the extra mass of the aluminum needed, compared to the cast steel might not be worth while. Also, you’d likely have a difference in tonal quality from the alum. vs. steel.

Mold costs and engineering are what will kill your budget (unless you’ve got a sky high budget, then by all means go for it.)

I asked a Piano Technician and he said they use cast iron b/c it’s so cheap. Really, the main acoustically functional parts of the piano are the soundboard and the strings. I figure If I can stay within 2-3 times the price, I plan on making other improvements that will offset that.

Well, thanks guys. I’ll keep this in mind as I go forward with my ideation and concept selection.

I’m sure they did… however, designing (using that word for engineering here…) in cast steel vs. cast aluminum will yield different results. You can have thinner walls on steel parts due to its higher strength.

Maybe this is something that should be machined instead of cast?

Hmmmm… I was under the impression that casting was more cost effective than machining.

This aluminum soundboard (which looks cast) seems to have a similar wall thickness to cast iron ones. The vertical walls seems like they might be a little (1.5x-2x) thicker.

I guess if the entire thing was machined, it might actually be more cost effective, since cast plates might require post-machining work for the pin board (all those fasteners for the strings).
DSC01726.jpg

Casting will be cheaper if your production numbers are higher (50,000 is quite a bit) but a one-off should be cheaper to machine.

You might be able to machine a thick sheet of Aluminum on a ShopBot Table router very, very slowly if you wanted to go the DIY route… I sure wouldn’t want to miss program a cutter on an expensive part like that though

Casting overall seems like the best route to me… you already have a master which you could make a mold, then you’d just need to find a place to pour

Yeah, there’s some confusion here… are you re-doing an existing piano? And already have the steel frame?

It sounds to me like he just needs the interal frame for a new piano design, but I might have miss-guessed

Just wondering, have you thought of just borrowing the original part or finding a cheap second hand piano to chop?

I apologize for the confusion!

I am actually designing a new piano for my Senior project, not hacking a real one. Given my time/cost/space constraints and that pianos have several thousand parts, I won’t be building my design, I just need to validate my materials choices. :smiley:

So, it seems like casting is the way to go. According to wikipedia, Aluminium alloy [6] 2014-T6 has about a 3.5x stronger tensile yield strength than Cast iron 4.5% C, ASTM A-48. Now I just need to figure out if that aluminum alloy is the cheap castable kind, and if that cast iron referenced is similar to the one used in piano plates.

I have actually been researching violins as well. This is just a final bit of research I’m doing before I decide which one to go forward with.


Thanks again for the advice, and sorry again for the confusion.