Investment and Sand Castings 1

[symphony123]

At my work, we have investement cast drawings and machine drawings for a particular type of product. Now somehow they want to try sand cast samples, can anyone guide what all kinds of issues i need to consider if i have to change an investment cast drawing to a sand cast drawing.
Do i need to just increase a .25" value to all dimensions so as to make it similar like an investment cast model once its semi finished from the sand cast stage.

Please guide to some direction regarding this..I appreciate all your help

 

[KENAT]

http://en.wikipedia.org/wiki/Casting_(metalworking)

may give you a basic idea of the differences in the two processes.

You may then want to check out potential vendors websites or otherwise contact them as they may have design guides that are of use.

KENAT,

Have you reminded yourself of faq731-376 recently, or taken a look at posting policies:

http://eng-tips.com/market.cfm?

What is Engineering anyway: faq1088-1484

 

[tomwalz]

sprues and vents

Thomas J. Walz
Carbide Processors, Inc.

http://www.carbideprocessors.com

Good engineering starts with a Grainger Catalog.

 

[BillPSU]

Depending on how complex of an investment casting you currently use the whole machining process may need to change. If there is a cast hole in the investment casting you may have to drill this hole. The finish on the sand casting will not be as smooth usually and details such as cast numbers and letters will lose some level of detail. Depending on what type of sand process green sand, no-bake or shell process the most effective process will need to be chosen.

The draft angles on the sand casting will be larger and parting lines will have to be cleaned up after casting also. This project is somebodies dream to reduce casting costs which it can do but then the other side of the equation that of machining an acceptable part will probably suffer.

Good Luck,

 

[swall]

On the plus side, the thermal gradients in a sand casting can be controlled, whereas those in an investment casting can't. This can make for a sounder casting. BTW, are we talking ferrous or non ferrous?

 

[arunmrao]

Discuss with your potential sand cast vendors the problems,they will be the best ones to guide you. My personal opinion,stick to investment castings,else any change you will be opening a pandoras box!


If you think education is expensive, try Ignorance.
- Andy McIntyre


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[ajack1]

Sand casting can also be done using a polystyrene model, this does away with the need for split lines and draft angles, and you can even produce undercut conditions. You do however need to make a poly part for every casting, so this option is dependant on numbers.

Sand casting also gives a very poor surface “skin”. As others have suggested speak to a foundry.

 

[mcrowder]

Not sure but have you tried these people, they have given us help in the past with detailed queries regarding investment casting.

 

[arunmrao]

mcrowder,they appear to be knowledgeable and competent. Good reference.


If you think education is expensive, try Ignorance.
- Andy McIntyre


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