Magnesium Casting

[MXMFG]

Any Info On Magnesium Casting ?

#1. The Right Tempurature To Pour.

#2. Any Misc. Info !

[lgreeves]

#1 - 1200` F

#2 - What are you using for a mold?

Mag is a nasty material in the molten state. It smokes bad, it pulls moisture from the air and start to burn. You don't want to get water or oil near it.

[MXMFG]

Green Sand For A Mold

[evildrome]

Hi,

I think you can just melt & pour but its very dicey. Normally you'd need a helper to direct a stream of cover gas (SF6) over the crucible & pour or you need to cover the melt & pour with powdered sulphur (very not nice).

SF6 is the least bad option.

Cheers,

Wilson.

[swagman]

to cast mag into a green sand mold you need to use inhibitors in your sand or the mag will turn into a roman candle. use 5% powdered sulfer and 1.5% boric acid powder. mix it really well in to the sand. dust the suface of the mold with sulfer be fore you pour. the sulfer creates an inert gas So2 which is released as you pour and pushes the air out, creating an inert atmospher in the mold cavity.the boric inhibits the reaction of the water in your green sand. pouring temp is 600 to 700 centigrade. you will need flux to melt with or the metal will oxidize dueing melting.
also use a stainer, such as steel fly screen at the parting line on the in gate or you will wind up with lots of crap in the casting, these will corode rapidly. and turn you casting into puffy fur ball. use old vw crank cases to experiment with, this az91 alloy and one of the best alloys.

[MXMFG]

ANY INFO ON CASTING MAGNESIUM INTO STEEL MOLDS ?

[lgreeves]

You will want to get your steel mold up to a tempature that will allow the material to flow without trying to solidify. The metal will need to be free of oil and water. Venting of trapped gasses or you get porosity. You will only has a short period of time(seconds) to get the part out of the mold due to the rate of shrinkage during cooling. If you are talking a large run, 100k or more parts, die-casting is the best way.

[swagman]

depends on the mold size. temp 680-750 centigrade. use insulating die coat. foseco 34. flush mold with sf6 prior to pour. to aviod cracking the die must be opened pretty quick, only a few seconds, depending on wall thicknes of casting. keep the mold 350 -380 centigrade. if cores are involved, a good system is to use shell cores. with inhibitors added. a strainer must be used to prevent inclusion. used AZ91c, this has good pouring qualitys and the c designates suitibility for perminant mold. a flux cover or sf6 must be used on the surface of the melt. the mold must be made from hot work tool steel. vent the mold liberally. thats the basics.

[lgreeves]

What is the cost of SF6?
With a short part run, it may be easier, faster, cheeper to machine from billet.