[JMFabrications]

Im in the planning process of having some of our parts investment casted, this is our first time using this process and unfortunately the upfront tooling costs are very high from the casting companies. I figured if I could machine my own mold it would save us a lot of money! We have a HAAS VF2 in house that we use for other items but I have no experience making a mold or designing one. I have a link to an IGS file and would like to get quotes on just the design. I will ultimately need to import this into Mastercam X so I can create the toopaths.

Any questions please contact me.

File

Thanks,
Jim

[HuFlungDung]

I see some conical surfaces, and some lines, but I'm not familiar with what I'm looking at, so it doesn't really make sense to me. Is this like a flat plate, with raised bosses and conical through holes?

[JMFabrications]

Its actually an exhaust manifold flange for a car, the port holes transition from round to an oval shape. It seems to come up fine as a solid model in Solidworks but im not sure what your using. The wireframe might be a little wacky, ill get you some actual pictures of the machined part shortly.

Jim

[advt001]

Is this a header flange?It should be a reasonable priced die if it is .

[JMFabrications]

The machined part right now is made from 3/4" thick 304 SS, as you can imagine this takes almost 2 hours per part and eats up the tooling. Ive got casting quotes for around $20 per part which is amazing, just need a mold

Attached are a few pics of the machined piece.

Thanks,
Jim

[JMFabrications]

Is this a header flange?It should be a reasonable priced die if it is .

Yes...the tooling quotes I got were in the $3000 to $3500 range. It would take me a long time to make that back on this part.

[HuFlungDung]

Not that I know much about this, but is this the 'lost foam' or 'lost wax' process, which?

I'm just wondering how feasible it is to job something out when one doesn't know how the casting outfit wants to do the procedure? I suppose there are many ways to make and fill the mold, but still, I imagine preferences do exist.

[JMFabrications]

Not that I know much about this, but is this the 'lost foam' or 'lost wax' process, which?

I'm just wondering how feasible it is to job something out when one doesn't know how the casting outfit wants to do the procedure? I suppose there are many ways to make and fill the mold, but still, I imagine preferences do exist.

Its going to be lost wax process. I still need to collect more info from the casting company about building the mold to suit their machines and figuring out the fill cavities etc. I was just trying to see if anyone had experience with this and roughly what kind of costs would be involved with just the 3D modeling. Ill get back with more info when I talk to them tommorow.

Jim

[JerryFlyGuy]

Looking at the Iges file I'm seeing the 'port volume' not anything like a manifold. Can you double check the file that you posted and see if we're missing something? Possibly post a Parasolid model vs the Iges?

Fwiw

J

[HuFlungDung]

It would be nice to know if a shrink allowance was required, too.

Do you expect these castings to be so good that they won't need touch up machining?

[rowbare]

If you are doing lost wax, then the purpose of the mold is to make wax reproductions for spruing. Your mold shouldn't have to be made of particularly exotic materials although the casting house probably wants something they can work with quickly.

Perhaps a silicone mold similar to what would be used for casting urethane would be adequate. Check out the videos at: http://www.freemansupply.com/video.htm and see if that might make sense.

[dpryor]

Jim,
Below is a pic of what I got out of the IGES file.
As I understand, do you just need a 3D CAD model of the part?

[mcphill]

Jim,

When I open that file in SolidWorks, I get 8 surfaces that just describe the through-hole walls. I can easily achieve what you want (though to be honest, I am not clear if you want a model of the part of of the mold), and I could provide you GCode to machine the part/mold if needed as well, but not with the data I have in hand right now. What CAD package was this created in? Can you post an STL of the file?

If needed, I could also scan in your part and reverse engineer the data from there, if you don't have all the data in CAD at this point in time.

Please e-mail me at mike(at)mcpii(dot)com if you would like me to look in to this further, but not much I can do with the data provided at this point.

Mike Phillips
MCPi

Im in the planning process of having some of our parts investment casted, this is our first time using this process and unfortunately the upfront tooling costs are very high from the casting companies. I figured if I could machine my own mold it would save us a lot of money! We have a HAAS VF2 in house that we use for other items but I have no experience making a mold or designing one. I have a link to an IGS file and would like to get quotes on just the design. I will ultimately need to import this into Mastercam X so I can create the toopaths.

Any questions please contact me.

File

Thanks,
Jim

[MrMold]

The molds for the wax injection is really quite simple. A couple of aluminum plates pinned together and some pry slots for screw drivers to seperate the halves and a simple runner and sprue to match the radius of the wax injector. I build these mold all the time for a couple of thousand dollars. The parts will still need some machining after casting and you'll probabally want to polish the ports so you need to add that into the equation. As far as saving a ton by making the mold yourself, that depends on what your time is worth and it sounds like you have little experience as a mold maker so you won't be as efficent as someone who does it everyday. You can definately make a pattern since you machine the parts from solid now. Just add shrink and cast a mold from urethane or silicone as someone suggested if the volume is low and the mold life is a few hundred parts. I bet you could make the mold design yourself after meeting with the investment caster, he should be able to show you what he needs for a mold and show you the process. Then in mastercam its as simple as modeling your mold plates, inserting the solid modeled part where you want it and doing a boolean subtract( Don't forget to add the the shrink). Investment caster should be able to tell you that also, although it depend on the caster. Some guy's make the molds themselves or have a mold shop make them and then tack on their markup. So shop around for one that will work with you. The process is really quite simple and thousands of years old. It's changed some from the days of using cow dung for casting bronze but the concept is the same. If you were trying to make a automatic plastic injection mold I would definately try and discourage you from attempting this with no prior experience. I still think that if you find a mold maker that builds a fair amount of this type of tooling that the $1500-2500 he should charge would be money well spent. However depending on how you value your time and the education your getting you can definately attempt it. But just because you can do something doesn't mean it's your best usuage of your time. I can sharpen end mills and do when I need something that is custom or right away, but I usually send them out because my time is better spent building and designing molds than sharpening end mills.

[cncjunky]

You should back out of your project. To many variables that you did'nt account for. This looks like a project that your going to dump alot of time into then realize after your about half way through that your not going to make any money. Being that it sounds like you don't have the experience to do these things on your own and you don't want to spend any money. It's going to be a time pit or a money pit, back out.

[mcphill]

Wow, that's pretty low on the "Can Do" attitude scale! No wonder all our stuff goes to China. So you lose money on a job, so what, you are investing in the process, and refining how to do it in the future. How would you learn new things if it required a profit every time? You would never add anything to your skillset that way.

[cncjunky]

Wow, that's pretty low on the "Can Do" attitude scale! No wonder all our stuff goes to China. So you lose money on a job, so what, you are investing in the process, and refining how to do it in the future. How would you learn new things if it required a profit every time? You would never add anything to your skillset that way.

Hey I totally agree with you. I'm not saying don't try to learn new things. If your doing it to learn so that in the future you can make cash go for it. Like me for instance I have a whole list of skills that I put time into to learn. Some payed off and some I'm still waiting for something to come around to recoup all the time and investments I've made in being able to use those skills. But if you don't see yourself profitng from all your time, effort and money then you need to find something else to do, unless it's just a hobby. I totally hate china and hate everyone that has sold us down the drain. I've lost jobs to freakin chinamen that I was within literally pennies $.05 - $.10 and these are Americans and Canadians that went with them over me and other Americans and Canadians. Thats why all of our stuff goes to china. Where did the china men get the knowledge and capabilities to do what they do? From the stupid American.(chair)

[JMFabrications]

You should back out of your project. To many variables that you did'nt account for. This looks like a project that your going to dump alot of time into then realize after your about half way through that your not going to make any money. Being that it sounds like you don't have the experience to do these things on your own and you don't want to spend any money. It's going to be a time pit or a money pit, back out.

Thanks for the advice but this is not just a hobby part, this will be used in our production products eventually eliminating the machined piece, this will definitely save us a lot of money in the long run. Ive got plenty of time, I own the company and the CNC so if I have to practice on machinable wax I cant imagine losing that much money. Its a bit of a learning curve but I can handle it!

Thanks everyone for their input, I have a call into the casting company and an engineer is supposed to get back to me with more info on the mold needed.

I realized the file I posted was not the right version, here is the correct one which may or may not help.

FILE

Thanks,
Jim

[mcphill]

I put this together yesterday, Jim, let me know if you are interested.

[John_B]

Jim,

I have worked in the investment casting industry for sometime now, where I make a number of the molds we use (not all of them because of time constraints and customer demands).

As Mark stated, a couple of aluminum plates is the basis for what you'll need, use 7050 or 7075. The injection runner diameter and path preferences is important to most foundries, as is the injection port detail. Any die guide track details are required too.

You'll need the shrink factor to work with as mentioned, as well as any taper requirements for the mold cavity walls - your part is pretty long and getting the wax out of the die will be fun without some taper to help it release, unless you want to use extractor pins with a push plate but that'll jack the cost up.

Best plan would be to make your part line at the flat surface of the 3/8" thick plate section with it and the cone features in one half and the raised gasket mating surface in the other. This is as mcphil has shown in his picture above, it's just hard to tell what the detail is (for a good reason I'm sure). You can add 1/2 to 1 degree draft to the 3/8" flange sides and it should pop out pretty easy. The 7/16" pins for the bolt holes should be on a pull plate that retracts out the back of either the top or bottom to help release the wax. If you don't pull those 8 pins out you'll get the wax racking over them and alot of trouble will be had in getting the wax out - which may raise your cost due to wasted time in the pattern department. These core pins will need to be no more than about .002" smaller than the hole they pass through in your die to keep it from flashing.

The best finish you should expect from your cast part will be in the 125 area, so again as mentioned you may need a little final touch-up machining. You probably will need to skim cut the mating surface to achieve a reasonable flatness and finish. I don't know whether you'll really need to polish anything as this is the exhaust side and some texture may not be an issue. Just be clear with your foundry about the finish acceptance (whether sand bite is Ok, positives/negatives Ok or not, miscellaneous inclusions, welding allowed or not, straightness requirement, heat treat condition).

You can do it. We have a customer that did not have any experience making wax injection dies start making their own. They have a huge amount of skill in other machining areas, and their dies are pretty smart looking - they do have problems but they are learning the niche...