Why magnesium alloy????

Started Apr 19, 2013 | Discussions thread
hariseldon2007
Regular MemberPosts: 117
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Toolmakers perspective
In reply to Cliff Fujii, Apr 21, 2013

As previously owning and running a uk toolmaker ( us term is tool and die) , a die casting tool is of similar cost to a plastic mould tool. release times for a plastic mould tool are not 4 minutes for a well designed tool which will use water cooling channels to  aid release.

aluminium in the raw form is very soft and is in my experience always an alloy, there  a large number  of alloys, various heat treatments and surface treatments to give different properties, some of which are very strong, as strong as a low carbon steel but much lighter.

Magnesium alloys die cast very well and have proven to be satisfactory for camera bodies over a period of time.

Titanium again comes in many forms and is very difficult to machine without expensive tooling, generally hard to fabricate, bit over the top for a camera.

Having a lot of design experience , selection of the right  materials, treatments is important and has to be balanced with how good does it have to be and how expensive is it to make a product. A durable, shock resistant plastic over a lightweight metal frame is  pretty good. An aluminium high tensile alloy chassis machined from sold would be  a technically sound solution but expensive, but a precision machined die casting is a pretty good compromise.

A camera needs a dimensionally stable frame for lens mount and shutter and sensor mount, pretty much the rest could be a tough plastic outer shell.

Apple have demonstrated that machined from solid aluminium alloy laptops are very good and economic for a high end , volume product. A MacBook is much stiffer and visually more attractive than a typical plastic laptop.

An expensive plastic we used in down hole oil field  instrument tooling is Peek, hard, rigid and very low thermal coefficient ( does not change dimensions very much when exposed to variations in temperature) , could form a good chassis for a camera body but I think there is little alternative to a hard wearing metal bayonet for the lens mount, and a metal thread insert for the tripod mount.

I suspect the camera manufacturers work on the principle of it ain't broke don't fix it!

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