Castings

[Lee Stohr]

ProMetal has machines that 'print' the sand mold directly from CAD model. No patterns are needed, no core boxes. The CAD model replaces the time consuming traditional pattern making. I believe ProMetal is the only company that can do this, but there are many other rapid prototyping processes that can also get you a casting. The technology is evolving rapidly.

What is really amazing is that once someone makes the CAD model of your part, a company like ProMetal can design the core box, vents, sprues, risers, gates, etc and then they simulate pouring the metal using computer software. If they find problems they can go back and change the sizes and postion of the gates, sprues, etc. So they will actually give you a firm price quotation for a good casting. You don't have to pour 2 or 3 parts to get a good one, like in the old days of foundry work.

This process allows prototype engines to be made and tested much faster than before, and the major car companies use it.

The process is economical and fast for larger one-off parts like engine blocks. Since there are no patterns, mass production isn't possible. They have to print a new flask (mold) for every part. The process isn't that economical for small parts like a water pump housing, unless you have nothing to use for a pattern and you are in a hurry. If you can make your own pattern or you have an old rusted part to send to the foundry, then this process probably isn't economical.

However, something like a cast iron engine block would cost around $8K. A second part is about $2K less. That doesn't include machining or the CAD model. Obviously the time and cost of drawing a CAD model depends a lot on the complexity of the part and how much information is available. Having a CAD model does allow blueprints to be made quickly for the machinist.

The aluminum bellhousing adapter that I made cost $2800 and 6 weeks to get.

About me: I am a mechanical engineer & CAD designer with an automotive background. I have built modern roadracing cars and I am also interested in auto history. I've been making drawings of Walter Christie's pre-WWI cars for several years.

If anyone needs help or advice with a one-off casting problem, I'll be happy to discuss it.

Edited May 28, 2012 by Lee Stohr
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[BearsFan315]

Very interesting, like you I am a Designer/ Drafter and we work with casters & molders around the world to create castings for our products (industrial Pumps & Equipment). Like you stated everyone wants a 3d model as they run the flow analysis and FEA on the models. Also we have several vendors that we work with similar to ProMetal that can do short runs, making just 1 or a few of an item direct from model in a very short lead time. Granted it is a little costly but you need it you want it you pay for it.

I love the design realm as it allows you to see the part as it will appear when complete you can create assemblies and see it all together, form fit, and function !!

What software are you using for your work ??

[Guest Mochet]

So the plastic models are placed in sand, and they dissolve in the molten metal?

Phil

[Lee Stohr]

There is a special kind of dissolvable pattern that works with investment casting, but that is not the ProMetal process. There is no plastic model in the ProMetal process, only a model in the computer. Their machine 'prints' the sand mold, layer by layer, around the imaginary part. So you end up with a fairly conventional sand mold with gates, sprues, risers, etc. For cast iron, ProMetal uses a foundry in Michigan that has cast parts for Ford, GM & Chrysler for 30 years.

[Lee Stohr]

CAD Software -

Most engineers like myself learned CAD solid modeling which is great for designing billet CNC machined parts. It never was great for designing organic shapes, like animals, people, etc. That's why computer gamers and digital movie animation people don't know anything about software like Solidworks, ProEngineer, Inventor, etc. They use sub-division modeling software, like 3DS or Luxology Modo. Since castings were often made from hand shaped wood patterns, I think you want software that allows easy shaping of the part in CAD. Although you can draw anything today in almost any CAD software, the sub-division modeling software is so much faster for casting design that I think it saves our customers a lot of labor hours. I use whatever software gets the job done most efficiently; that could be Rhino with T-Splines, or Solidworks, or Inventor or even an old CADKEY program.

Lee

Edited May 29, 2012 by Lee Stohr
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[BearsFan315]

Only thing cooler then watching the video is actually being there while this is done. But when the pour you stay way back , and it is HOT !! and casting facility are pretty nasty especially rough sand casting. But it is really cool, our company has been getting into the lost foam method of casthing, as it is a wuick variable casthing process that gives you pretty darn accurate products. You can cast in holes that you used to have to machine, saving lots of time.

As for the software I did not know if they used an off the shelf software for design or had their own in house software.

[Grandpa]

Harry J.

You may want to check with the ACD folks, as someone has re-cast the iron cylinder head for the Duesenberg Model J. I think that the cost came to about $42K each because of the complexity and number of the cores required for the mold.

Grandpa

[Restorer32]

The castings themselves are cheap. It's the patterns and cores that eat up money. We use a local Amish foundry that will still work with original pieces for patterns to do silicon bronze, aluminum and cast iron but there obviously are limitations to where simple sand castings can be used. Convertible top pieces, various mounts, step plates, taillight stanchions are examples of items that can be easily cast from originals because precision is not a big issue and shrinkage can be taken care of by building up the original a bit. Great new technologies coming along but unfortunately they seldom have much application to very short run relatively low value castings as needed by antique car restorers. If those Duesy heads cost $42k it is likely that the actual castings were under $1k, possibly even under $500 with the rest of the cost being R&D and pattern making. As an example we do Packard taillight stands in silicon bronze. The actual castings cost only about $35 but the machining and polishing take several hours so the cost ends up being up there. I'm curious as to how much computer time it takes to do a cad drawing of say a 4 cylinder exhaust manifold and what the price per hour is.

[Lee Stohr]

Might be $800 for me to draw an exhaust manifold. The mold is made directly from that CAD drawing. I don't have to draw cores. However, the ProMetal process is more economical for complex parts like engine blocks and head. Re-creating parts like that takes a long time (years?) the traditional way, and requires many cores and fixtures to hold them. Doing it the old way, I've seen the first few castings aren't any good, they usually get cut up to see what went wrong.

[Restorer32]

The old time wood pattern makers were highly skilled and well paid. They were replaced by the plastic pattern makers who are now being replaced by computers. Evolution isn't just for living organisms.

[Lee Stohr]

For small, simple parts the old way is still the most economical. There are still foundrys around that can take an old cast bracket and build it up with bondo or whatever to account for shrinkage and then use it as the pattern. And wood workers are really getting into CNC carving machines, which are cheaper than metal CNC milling machines. But if you need lots of core prints for a complex part, I think the new way is better for one or two parts.

[Restorer32]

Agreed. Some times you just have to step up and pay the price.

[Coley]

Quote:

I'll be in Philly if the creeks don't rise.

Refers to the Creek indians, not a water crossing.

[HarryJ]

Folks........we're really starting to build a knowledge base. I recently attended an engineering conference being held here in Atlanta by the Society of Manufacturing Engineers. I signed up and attended a course taught at the conference. This national conference was focused entirely on rapid prototyping and reverse engineering. It lasted three days. Here is a copy of the cover of the course's textbook............

[Lee Stohr]

I just found out there is a AACA Sentimental Tour based here in Staunton, VA next week. Staunton was recently chosen as the 10th best small town in America by Smithsonian magazine. I'll be visiting Bruce Elders Antique & Classic Car store, downtown Staunton, on Sunday (tomorrow). I'd be happy to talk castings with anyone interested.

[Max BURKE]

G,day to all

In the early 1960s we had a Cat 12 grader that split the main trans housing. After several cold CI welding attempts and an exercise with CI metalock plugs we striped it out and i took it to Sydney to Speedy Welding co.Mr Speedie was in his eightys,son Barry was conducting the business. While waiting i talked to the elder and in the conversation he told me of a process they had used to produce replacement cylinder heads for the many side valve engines that were fitted with alluminium heads that coroded away with electrolisis.They made the replacement in two sections,that is they were jointed full length . A gasket between each section sealed the joint.Spark plugs in the bottom piece. This production method eliminated the need for a core. They had on their shelves mabe 200 of these replacements with no longer any demand for them.I expect this method is well known in the foundry trade but i often think what a shame if the stock of heads went into the scrap bin when the shop closed.

By the way the Cat housing, Bronze welded in the furnace and cooled over a week never gave trouble again.

Max BURKE Nulkaba Australia

[W_Higgins]

While this discussion is being brought back to the top, an excellent resource to add to ones Rolodex is:

Cattail Foundry

Emanuel J. King

167 W. Cattail Road

Gordonville, PA 17529

(717) 768-7323

I've visited them and seen their work firsthand. I'm not saying that they are capable of casting an entire engine block, but the regular work I saw there was outstanding and they are very reasonable. Certainly good enough for lots of regular car parts. The article linked to below will give you an excellent look at their work and business style. They story behind it is just wonderful:

Short story and pics of Cattail Foundry's work

Cheers!

[Guest stude8]

I attended the Mercer Centennial meet at Roebling, NJ in 2009. There was a 1921 Mercer L Head 4 cyl engine roadster there with a reproduction engine block. The owner was from California I believe and he told the story of how they disected an L head block to obtain interior casting pattern shapes and had a Japanese owned casting shop in California do a pilot run of 10 cylinder blocks with the idea of selling 9 blocks to offset the high cost of the reproduction.

After the casting run only 2 of the 10 castings were found to be useable due to pattern shifting during the casting process. The attached photo is of the one successful reproduction engine in the 1921 Mercer.

Stude8

[Lee Stohr]

One of the amazing things about the new CAD to Casting processes is you will get a firm quote for your part. If there are scrap parts, ProMetal eats them. They are confident that won't happen, because they can simulate the pour on computers before sending the mold to the foundry. Regardless, you have a firm contract in hand.

However, for simple parts like those shown in Mr Higgins post, it is much cheaper to use an old part. If you don't have a part, make a wood pattern or get an engineer to make you a plastic pattern and use a foundry like the Cattail Foundry.

Lee

Edited June 4, 2012 by Lee Stohr
more info (see edit history)

[Restorer32]

While this discussion is being brought back to the top, an excellent resource to add to ones Rolodex is:

Cattail Foundry

Emanuel J. King

167 W. Cattail Road

Gordonville, PA 17529

(717) 768-7323

I've visited them and seen their work firsthand. I'm not saying that they are capable of casting an entire engine block, but the regular work I saw there was outstanding and they are very reasonable. Certainly good enough for lots of regular car parts. The article linked to below will give you an excellent look at their work and business style. They story behind it is just wonderful:

Short story and pics of Cattail Foundry's work

Cheers!

We use Cattail on a regular basis. Nice Amish folk who will do good work for you unless they get the idea you are taking advantage then you are out. I suspect they would have no problem doing an engine block given the necessary patterns and core boxes. Their specialty is early steam engine replacement parts, especially Frick.

[HarryJ]

stude8................I saw the Mercer castings at Hersey 3 or 4 years ago..............they are very good!