Recommendation on Magnesium alloy 4

[kilkenny]

I want to machine a small housing for electronics out of magnesium. (think portable computer, tablet pc or lightweight but rugged electronics) Usually I use 6061-T6 aluminum.
1) What magnesium alloys are commonly used in machining applications where availability, ability to coat for corrosion and good strength are required?

Eventually this will be made into a casting or injection molded parts, which leads to my second question:
2)What alloys should I look at for die casting, injection molding, or thixomolding for the same types of applications?

Thanks,

Kilkenny

 

[metengr]

For starters, here is some background information on magnesium alloys, and properties to review;

http://www.castingsource.com/tech_art_Magnesium.asp

 

[CESSNA1]

KILKENNY: Why magnesium? It offers no significant advantage over aluminum that I can see except maybe weight. For small stuff the weight difference is probably negligible. Magnesium is more expensive than aluminum.

Regards
Dave

 

[CoryPad]

CESSNA1,

You should educate yourself on materials selection, magnesium alloys in particular. Magnesium alloys offer higher specific strength and specific stiffness than aluminium alloys, and with their low melting enthalpy and lack of reaction with steel dies, they offer lower casting costs. The cost of Mg ingots is now comparable to Al ingots.

kilkenny,

At the current state of the art, the alloy choices really are AZ91 or AM60. The link above shows some properties - others you can get from your material source. If you need help selecting a source, try the search function from the North American Die Casters Association:

http://www.nadca.org/imisweb/scriptcontent/DieCasterSearch.cfm

Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[TVP]

kilkenny,

For machining applications, you may want to consider a wrought alloy like AZ31. However, this may not be a good way to validate the design concept if casting or molding will be used for production. I would discuss prototyping with a good casting or molding vendor. If you do want to investigate wrought Mg, contact Spectrulite.

 

[PNN]

Kilkenny,

If you are looking at building Mg electronics housings, consider Thixomat. (

http://www.thixomat.com)

This company has a patented semi-solid casting technology that is used to produce cellphone bodies, ruggedized laptops, etc.

Thin walls (~1 mm) and tight tolerances (0.0005"/inch) are possible. The tooling is similar to that used in diecasting.

Good luck.

 

[CoryPad]

PNN,

Kilkenny specifically mentioned thixomolding in his first post. THIXOMAT only licenses the technology - s/he will need to contact a company that has a license and actually makes parts. Here is a list:

http://www.thixomat.com/parts.asp

Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[btrueblood]

Corypad,

In addition to the other advantages you mentioned, I'd add that Mg alloys also have relatively high vibration dampening (similar to cast iron). We have used Mg alloys many times for vibration test fixtures; the dampening of Mg (vs. Alum. alloys) helped solve some nasty resonance problems.

 

[magplate]

The most common alloys by far are AZ31B for machining and AZ91 for casting. FWIW I find the high pressure die cast parts are less porous and more easily coated than thixomolded parts.