Drawings for casting
Drawings for casting
(OP)
I have made a model / drawing of something we are now machining out of solid stock.. Because there is so much waste we are thinking of having this cast.
I have never seen a drawing showing cast dimensions.. Can anyone point to some possible samples.. possibly something like a pillow block bearing.. most of it will remain with a cast finish yet some parts must clean relative to the cast areas / pockets etc.. How does one show this on a drawing?
Thanks for your time
Ralph
I have never seen a drawing showing cast dimensions.. Can anyone point to some possible samples.. possibly something like a pillow block bearing.. most of it will remain with a cast finish yet some parts must clean relative to the cast areas / pockets etc.. How does one show this on a drawing?
Thanks for your time
Ralph






RE: Drawings for casting
Does anyone still supply drawings for castings these days?
RE: Drawings for casting
Jeff Mirisola, CSWP, Certified DriveWorks AE

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RE: Drawings for casting
RE: Drawings for casting
Remodeling / sizing the whole thing, dimensioned only to the cast areas seems to be the best option.
RE: Drawings for casting
Different casting companies do them differently.
When modeling, I create the casting model then make an assy from it and remove material for the machined part.
Try a search here for specs:
http://www
thread1103-233035: Specs
Chris
SolidWorks/PDMWorks 08 3.1
AutoCAD 08
ctopher's home (updated Aug 5, 2008)
ctopher's blog
SolidWorks Legion
RE: Drawings for casting
The only other trick is figuring out how to specify acceptable prosity. For that I recommend you get your vendor picked out!
-b
RE: Drawings for casting
I strongly agree with ctopher's suggestion. His 3D model follows your fabrication process, making documentation more logical. If your machining is done by a different vendor than your casting, you absolutely need two separate drawings. Make sure both of your vendors have the same set of datum features to work to. Foundries recommend casting datum targets into the part.
Another issue is that you might want to do a different machining process on your casting to make to new part. Ctopher's method makes this easy.
RE: Drawings for casting
RE: Drawings for casting
I dislike the assembly method because it creates an assy where one does not actually exist, but I understand the usefulness of having the "raw material" called up in a BOM.
Whichever method best suits the product and company procedure is the one which should be used.
RE: Drawings for casting
Doing it in the model is fine (and how I'd do it), just don't show it on the drawing.
-b
RE: Drawings for casting
RE: Drawings for casting
I would recommend using the same supplier for both the machining and casting. If anything goes wrong there will be a lot of finger pointing and only have 1 supplier that is 1/3 less fingers to sort out.
RE: Drawings for casting
A lot of cast supplies are not really into finishing/machining a cast part. Some suppliers will do targeting machining (another subject) for best possible cast to machine fit. I would find a machining supplier to purchase/procure the cast part, and then send you the finished part. Similar to what GRF stated.
I don't know what type castings you're designing or what materials you're using, but do have a couple recommendations:
Sand Cast (Aluminum) - Use .120 nominal cast to machine cleanup on faces and diameters. There's a lot of shifting of casting cores especially if it's a complex housing. If you have small internal core sticks, make sure your wall thickness are no thinner than .190. The cast supplier will love you for this. Wall thicknesses will also depend on internal pressures of your design.
Investment Cast (Aluminum) - Use .060 nominal cast to machine cleanup on faces and diameters. Investment Castings are a lot more accurate than Sand castings, and also cost more because of tooling.
The best idea is what the others commented on. Find a cast supplier and deal directly with them. DO NOT define parting lines; let the cast supplier do that for you. It will save you a lot in tooling cost. If you have a problem were there located, talk with the cast supplier. Also, keep in contact with the cast supplier at all times. Notify them of any changes immediately. It could save you thousands of dollars in tooling charges.
Hope this helps,
Colin Fitzpatrick (aka Macduff)
Mechanical Designer
Solidworks 2008 SP 4.0
Dell 490 XP Pro SP 2
Xeon CPU 3.00 GHz 3.00 GB of RAM
nVida Quadro FX 3450 512 MB
3D Connexion-SpaceExplorer
RE: Drawings for casting
"who does it that way"
--
Hardie "Crashj" Johnson
SW 2008 SP4
Nvidia Quadro FX 1000
AMD Athalon 1.8 GHz 2 Gig RAM
RE: Drawings for casting
Users and companies have different methods of modeling castings and machinings. My preference is to have the casting as the master, and insert it into another SW part to do my machining operations. My color preference is: exterior casting surfaces color gray, interior casting core surfaces color light blue and machining surfaces color red. I try and stay away using configurations in this case. This is just my opinion.
Colin Fitzpatrick (aka Macduff)
Mechanical Designer
Solidworks 2008 SP 4.0
Dell 490 XP Pro SP 2
Xeon CPU 3.00 GHz 3.00 GB of RAM
nVida Quadro FX 3450 512 MB
3D Connexion-SpaceExplorer
RE: Drawings for casting
I would recommend having a cast drawing separate from the machining drawing. I know some aerospace companies have it combine into one drawing, but makes it difficult to interpret base on its complexity.
Colin Fitzpatrick (aka Macduff)
Mechanical Designer
Solidworks 2008 SP 4.0
Dell 490 XP Pro SP 2
Xeon CPU 3.00 GHz 3.00 GB of RAM
nVida Quadro FX 3450 512 MB
3D Connexion-SpaceExplorer
RE: Drawings for casting
RE: Drawings for casting
Now, we are getting really detailed about this, and outside the scope of this SolidWorks forum.
Find a textbook on Design for Manufacture And Assembly (DFMA). Read up on how you should minimize the number of parts. A carefully designed casting can be very complicated, and perform a lot of functions, each of which, otherwise, would require a separate part, which must ordered, fabricated, stocked, kitted and attached to your final product.
The best strategy for machining is to not do machining. Make the sloppy casting tolerances work in your assembly. Make the surface finishes work in your assembly. If you must machine your casting, make sure that all the machining can be done in one setup. If it takes four or five setups to machine your casting, it be easier just to CNC machine the thing from billet.
RE: Drawings for casting
RE: Drawings for casting
With material costs as they've been for the last 10 years it's very economical even with a few machining operations.
They type you need is going to depend on what you need, and what kind of quantities you need. Do some research, send your part out (as is) for quotes from casting companies. Don't be afraid to ask for any thoughts to make the part easier for them to make without losing functionality.
James Spisich
Design Engineer, CSWP
RE: Drawings for casting
Chris
SolidWorks/PDMWorks 08 3.1
AutoCAD 08
ctopher's home (updated Aug 5, 2008)
ctopher's blog
SolidWorks Legion