Permanent Mold Casting

[Rio79]

Oh wow! I didn't realize there was a casting section in this CNC forum! Sweet!

So I was just wondering if anyone has any good resources for permanent mold casting with aluminum. A good link, an engineering book, a simplified DIY book/links perhaps...

I'm just getting started so any info is appreciated!

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[DMF_TomB]

i can only tell me experiences with permanent mold casting.
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with cast iron into a cast iron mold the mold wall need to be thick. i have had castings stuck to the mold a few times.
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had a drop of water (rain) in a mold once. when molten cast iron hit it it was like being in the middle of a fire works explosion. not so pretty when your in the center of sparks / molten metal flying in all directions.
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found out using an oxygen acetylene torch with oxygen off you get a smokey flame that preheats, dries out water, and coats metal with soot to help keep metal from sticking to mold.
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you need a lot of draft or taper, smooth surfaces and allowance for metal to shrink with out it grabbing the mold.
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it is lot easier to use a lower melting point metal like babbit or zamak. i have pouring lead sinkers into an aluminum mold without any problems. they sell blank molds for making fishing sinkers. all you got to do is machine them and a gate / funnel to pour metal in them.
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i never made any die casting molds where metal is injected under pressure. i believe their are many books on die casting. try searching Amazon.com

[jimmy111]

I know.
Im late.
For permanant mold casting of Aluminum, Cast Iron works best. Specifically I use Dura Bar. It is a special cast iron and you can get it in many sizes.
Either G1 or G2 will work fine for molds. It is about $1.00 per pound right now.

Use a mold wash and you ALWAYS preheat the molds to 400F or so. Never pour hot metal into any room temp mold. You are just asking for trouble.

[slowlearner]

I would like to make a correction to a preceding post. I paid $ 3.22 a lb. for class 30 Durabar this week. We quote perm-molds daily so I am sure my numbers are the rate this week. If you are in the southeast I can also reccomend a supplier for mold coatings.

[jimmy111]

I would like to make a correction to a preceding post. I paid $ 3.22 a lb. for class 30 Durabar this week. We quote perm-molds daily so I am sure my numbers are the rate this week. If you are in the southeast I can also reccomend a supplier for mold coatings.

You are getting screwed on the durabar. My last order was a small order of 2 blocks of 150lb each for a total of 300 lb. Price inclucing truck delivery of about 600 miles was $408.00.

A mold release that works pretty good if you dont have any access to anything else is BBQ charcoal Briquites. They are not all the same but it is cheap. just grind one up and mix it with alcohol untill you get a consistancy that will spray thru a spray bottle. then just spray it on and it will stick. You get nice shinny castings with little dross or oxide.