engine construction and resistance.

[no longer collecting]

Does anyone knows why some saws are made from ??"sand cast aluminium"...other are " die cast aluninium"...some are "sand cast magnesium" and others are "die cast magnesium". i had parts repaired on some saws that needed welding and this is when i lurned about this fact from the welder guy.What are the advantages of such different molds?????A BIT CONFUSED. I need a pro on this one.....

 

[Bob Wright]

Die casting used molds with the liquid alum or magnesium being forced in under pressure. The finished parts don't need much machining if any. Sand cast is as implied sand is put in a box and the liquid metal is poured in around it, then the parts are machined. Magnesium is a little lighter than alum. It can still be welded but you should use a tig welder because it will catch on fire when working with it...Bob

 

[Crofter]

In the sand casting process the metal cools off relatively slowly compared to die casting. The cooling rate affects the grain and whether segregation of the alloy elements gives a good product or not. Some excellent alloys need special heat treatment and are unsuitable for sand casting or welding. It is a real crap shoot unless you have tried the particular alloy or have specific welding directions from the manufacturer. I have seen grain structure as coarse as rock salt in the failure of what looked like a good weld at the time of completion.