Why magnesium alloy????

Started Apr 19, 2013 | Discussions
(unknown member) Veteran Member • Posts: 3,348
Re: Why magnesium alloy????

I've often wondered why Carbon Fibre is not used in camera bodies much.

If we can build planes and cars out of it  I would have thought cameras, lens barrels and so on were possible too.

(unknown member) Veteran Member • Posts: 3,348
Re: Titanium vs. aluminum strength to weight ratios...

Joseph S Wisniewski wrote:

trekkeruss wrote:

leicaman wrote:

Magnisium is hard, light and cheap... it can be cast.

Aluminum must be machined and is heavier.

Titanium is the best, lighter and stronger but is hard to machine and hugely expensive.

Titanium is heavier than both aluminum and magnesium.

And that matters why?

Titanium has a strength to weight ratio of  288 kN·m/kg, nearly twice that of magnesium at 158 kN·m/kg. So, something the same weight is twice as strong when made from titanium. Or, if you're aiming for a specific strength, the titanium part is half the weight,

It is more commonly used as a lighter weight replacement for steel.

Except that it's not. Most steels have a higher strength to weight ratio than titanium. So it's worse if you're designing to a particular strength or a particular weight. Where titanium shines is that it's half the density of steel, so if you're designing to a particular volume, it may be adequately strong for your purpose, although weaker than a  steel part of the same volume.

I believe Titanium is also much more resistant to corrosion than most steels so is used when that is important.

nofumble Senior Member • Posts: 2,107
Metal casting

I am not a metal casting expert but have engineered many products using cast/mold over my career.

Magnesium has some advantage over others

-low melting point.

- Almost no shrinkage during solidification.

- Good fill rate

These properties make it a material of choice for casting. In fact, my supplier can use the same LCD plastic mold to mold magnesium.

However, the molten magnesium is very fire hazardous. The mold must be done in vacuum or in inert gas environment. There are only a few molding house that can handle Mg molding.

Aluminum is higher strength than Magnesium but its moldability is limited, and can't hold tight dimension.

Titanium - no this stuff is more useful for something like jet engine instead. Titanium golf-club should be banned. Sorry.

A well engineered poly-carbonate with glass fiber and metal-structure backing will do just fine. Best engineered product is to make it functional and affordable for as many people as possible.

Stainless steel - good for making a stick to whack on the head of whoever is asking for.

krikman Regular Member • Posts: 418
Re: Metal casting

A well engineered poly-carbonate with glass fiber and metal-structure backing will do just fine. Best engineered product is to make it functional and affordable for as many people as possible.

So why we ever need to change metal bodies to plastic one? Just to show that it can be done?

(unknown member) Senior Member • Posts: 1,146
Re: Why magnesium alloy????
1

krikman wrote:

Message for all plastic-fantastic agents:

Don't see Discovery channel and don't drink too much.

Material choice never made by only one parameter, it is complex value including tension and compression strength, expansion factor, chemical stability, poison gas emission etc.

All composite plastics emits poisonous gases while in low quantities, have not uniform direction strength, very difficult to mill and no dimension precision. They're perfect for simple forms covers and panels. In Airspace technology they used not as chassis, but as linear and honeycomb fill to some parts. Parts of wing sections in aircraft isn't made of plastic, but from composite 'sandwich' including layers of pre-taut fiber net in epoxy resin fill. They are simple panels, tubes.

When aircraft manufacturers need strong box as in centerplane section or chassis base they used titanium or magnesium milled boxes. So never any serious equipment use plastic as structure material. It was and still is. (computer servers, concentrators, printers, any non-home components still made of steel).

There is another very important reason: heat dissipation. Lots of electronic cirquits inside of reasonably fast camera need heat transfer. No plastic can provide it so no fast, professional camera in plastic box.

So magic fiberglass, carbon-fiber, kevlar, carbon nanotubes etc. still found exotic, highly restricted usage mainly for outer panels and as destructible shields. At least in our millenium. All other is bad journalism and non-science fiction.

The Boeing 787 is 80% carbon-fibre reinforced plastic composite by volume. This is the primary material used in the fuselage barrel sections.

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BartyL

krikman Regular Member • Posts: 418
Re: Why magnesium alloy????

BartyLobethal wrote:

krikman wrote:

Message for all plastic-fantastic agents:

Don't see Discovery channel and don't drink too much.

Material choice never made by only one parameter, it is complex value including tension and compression strength, expansion factor, chemical stability, poison gas emission etc.

All composite plastics emits poisonous gases while in low quantities, have not uniform direction strength, very difficult to mill and no dimension precision. They're perfect for simple forms covers and panels. In Airspace technology they used not as chassis, but as linear and honeycomb fill to some parts. Parts of wing sections in aircraft isn't made of plastic, but from composite 'sandwich' including layers of pre-taut fiber net in epoxy resin fill. They are simple panels, tubes.

When aircraft manufacturers need strong box as in centerplane section or chassis base they used titanium or magnesium milled boxes. So never any serious equipment use plastic as structure material. It was and still is. (computer servers, concentrators, printers, any non-home components still made of steel).

There is another very important reason: heat dissipation. Lots of electronic cirquits inside of reasonably fast camera need heat transfer. No plastic can provide it so no fast, professional camera in plastic box.

So magic fiberglass, carbon-fiber, kevlar, carbon nanotubes etc. still found exotic, highly restricted usage mainly for outer panels and as destructible shields. At least in our millenium. All other is bad journalism and non-science fiction.

The Boeing 787 is 80% carbon-fibre reinforced plastic composite by volume. This is the primary material used in the fuselage barrel sections.

It perfectly fits my conclusions: most of the outer panels and bulkhead consist of composite materials, while platforms for mashinery and key elements made of titanium and alumnium. Proportion nearly same as for current D4 class body. They have 80% by volume plastic and rubber too...

krikman Regular Member • Posts: 418
Re: Why magnesium alloy????
The Boeing 787 is 80% carbon-fibre reinforced plastic composite by volume. This is the primary material used in the fuselage barrel sections.

D4 body completed with carbon-fibre may cost more than milled from clear gold. At least today.

(unknown member) Forum Pro • Posts: 13,144
Re: Why magnesium alloy????

leicaman wrote:

Magnisium is hard, light and cheap... it can be cast.

Aluminum must be machined and is heavier.

Titanium is the best, lighter and stronger but is hard to machine and hugely expensive.

A Titanium Leica M  body is $9000+

Aluminum most certainly can be cast.

A356, A350, and ADC12 are all cast aluminum alloys.

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(unknown member) Veteran Member • Posts: 3,348
Re: Titanium vs. aluminum strength to weight ratios...

Kleeks13 wrote:

Joseph:  I realize that in addition to being a photographer, you are an engineer. I am fascinated by your answers and knowledge about different materials.  I was in a car accident and my legs were crushed.  They have been rebuilt and are 70% titanium.  I'm always curious about that material.  Do you have a references for the lay person? ....titanium and the human body?  I always have health problems, but, believe it or not, my orthopedic doctors don't have the answer to many of my concerns.  Well, one problem I know is that it doesn't float. I use a pull buoy to swim or my legs go straight down to the bottom of the pool. LOL

The other 30% is bionic, I hope, Kleeks!

Catalana Senior Member • Posts: 1,259
Re: Why magnesium alloy????

3,000,000 milligram sounds more impressive,

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cplunk Senior Member • Posts: 1,834
Re: guns

RedFox88 wrote:

Cliff Fujii wrote:

If you are talking about 3D prototyping using 3D copier, those guns would be usable for a very short time, or the caliber was very small.

It only takes one bullet shot to kill someone, right?  How long is will last is not what's important.

better get close, it'll fall apart trying to site it in.

But, as comparison to making cameras, if it only takes one picture and is then worthless, no one's gonna guy that.

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Kleeks13
Kleeks13 Regular Member • Posts: 336
Re: Titanium vs. aluminum strength to weight ratios...

I know (body doesn't react)..however...the bone gives, but the titanium doesn't...the source of most of my pain.  I have a "bone-in" hip replacement.  Unlike hip replacements for the elderly, which are cemented,  a bone-in has holes and your bones grow through and around.  ...always a fascinating topic.

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Kleeks

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Kleeks13
Kleeks13 Regular Member • Posts: 336
Re: Titanium vs. aluminum strength to weight ratios...

MPA1....I just wished I had the healing capabilities of Wolverine. LOL

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Kleeks

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(unknown member) Veteran Member • Posts: 3,348
Re: Titanium vs. aluminum strength to weight ratios...

Kleeks13 wrote:

MPA1....I just wished I had the healing capabilities of Wolverine. LOL

Ahaha!

As long as you don't make that funny noise Steve Austin used to make when you run..!

(unknown member) Veteran Member • Posts: 3,348
Re: Metal casting

You can cast quite complex shapes in Stainless steel.

I have the original Gitzo Ocean Traveller tripod. The metal parts are all SS.

The 'spider' was made by a process whereby particles of stainless steel were mixed with resin and formed into what is an amazingly fine and delicate structure.(something like that anyway!)

The resin/steel part was fired at no doubt very hot temperatures, melting the resin away and fusing the SS particles into a single structure. As tripods go, it really is a work of art.

Horridly expensive as a result though!

joneil Regular Member • Posts: 179
Re: Metal casting

Warning - Tongue in cheek mode = ON

You need to walk around for a while with a steel body 4x5 or even a steel body 8x10 large format camera.   After a couple days, you'll never question the need for magnesium camera body ever again...

(unknown member) Veteran Member • Posts: 3,348
Re: Metal casting

joneil wrote:

Warning - Tongue in cheek mode = ON

You need to walk around for a while with a steel body 4x5 or even a steel body 8x10 large format camera.   After a couple days, you'll never question the need for magnesium camera body ever again...

Ah well, that is why they have servants and bearers, old chap!

CraigBennett
CraigBennett Contributing Member • Posts: 699
Re: Why magnesium alloy????

I wonder if the same discussion occurred when cameras went from wooden bodies to metal?  I can just hear it now.....why change with want's working?  That body will rust, no resilience, etc, etc, etc.... next it will be plastic.  What's the world coming too?

Regards,

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noirdesir Forum Pro • Posts: 13,561
Re: Titanium vs. aluminum strength to weight ratios...

Robin Casady wrote:

Kleeks13 wrote:

Joseph:  I realize that in addition to being a photographer, you are an engineer. I am fascinated by your answers and knowledge about different materials.  I was in a car accident and my legs were crushed.  They have been rebuilt and are 70% titanium.  I'm always curious about that material.  Do you have a references for the lay person? ....titanium and the human body?  I always have health problems, but, believe it or not, my orthopedic doctors don't have the answer to many of my concerns.  Well, one problem I know is that it doesn't float. I use a pull buoy to swim or my legs go straight down to the bottom of the pool. LOL

Titanium is used in orthopedic cases because it is not reactive in the body, and bone will bond to it.

In lay terms, it doesn't rust.

krikman Regular Member • Posts: 418
Re: Why magnesium alloy????

CraigBennett wrote:

I wonder if the same discussion occurred when cameras went from wooden bodies to metal?  I can just hear it now.....why change with want's working?  That body will rust, no resilience, etc, etc, etc.... next it will be plastic.  What's the world coming too?

Regards,

Wooden cameras much better than plastic ones.

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