Metal casting

Foundry
http://www.practicalmachinist.com/vb/general/anyone-have-homemade-aluminum-foundry-r-cast-s-machinable-strength-237445/ The crucible material is important too- cannot use steel/iron pipe anywhere in the process, it will dramatically contaminate the aluminum, which is effectively a pretty good solvent for it when molten. Also consider how you're going to evaluate the alloy in your castings, which means probably you'll need to pour several molds per melt so you can cut up and test some, then repeat the process until the final alloy more or less conforms to some kind of spec adequate for the application.

For openers, use a metal of known alloy. One that has worked well is 713 (Tenzaloy™). After that are good foundry practices, degassing, keep iron away from the melt, good mold practices such as gating, risers and venting.

http://web.archive.org/web/20060214123826/http://www.aomevents.com/conferences/afi/papers/Taylor.pdf The Effect of Iron in Al-Si Casting Alloys

If you want to make a casting then you need a cast alloy. thus you melt castings, transmission cases, cylinder heads, etc. As previously stated it must be in a refractory lined vessel. DO NOT ADD OTHER CRAP. Cans and chips will burn up and create a lot of dross to be skimmed off. Sheet items, wire, etc will alter your alloy and likey prevent it from flowing and filling the mold. A layer of common table salt will reduce oxide formation. I'm sure it can be done but is it worth while? Is this an irreplaceable part?


 * http://alloyavenue.com/vb/forum.php Casting foundry discussion forum.
 * https://www.reddit.com/r/Metalfoundry/comments/37k7bb/aluminiumzinc_alloys_what_composition_gives_the/

Oxidation of melting metals
http://www.rsalloys.eu/cmsMateriali/produzioni/13/aluminium%20beriyllium%20master%20alloy.pdf Small quantities of beryllium, when introduced to magnesium and aluminum melts, provide substantial manufacturing benefits in terms of direct cost savings and pro- duct quality. When beryllium is added to the melt in small quantities much of it forms beryllium oxide. As a surface film, beryllium oxide creates a superior barrier to further oxidation. The improved barrier inhibits dross formation, limits magnesium ignition and improves metal yield. By preventing oxygen migration into the melt, the beryllium addition enhances metal cleanliness leading to improved mechanical properties and visual characteristics of the casting.

http://www.backyardmetalcasting.com/faq.html Can I use soda and/or beer cans as an aluminum source? Yes you can but there is a "trick" to using them successfully. Since the cans are so thin they easily burn and oxidize rather than melt. For this reason many people say they should not be used. But if you already have a good pool of molton aluminum in the crucible then the can can be melted efficiently by crushing them (top to bottom) and dropping them into the pool. If the dry cans are pushed below the pool's surface they will melt and be less likely to oxidise. This aluminum is almost pure (unlike car cyclinder heads which are alloys). So the metal will usually shrink more when cast. but it is extream;ly shiny making it good for small decorative castings.

http://www.substech.com/dokuwiki/doku.php?id=degassing_treatment_of_molten_aluminum_alloys

http://www.hkramer.com/4KramerGoodFoundryPractices.pdf good foundry practice