Could I make a carabiner's pin/rivet out of copper instead of steel? 8

[panosjapan]

Hi,
I am making a carabiner which won't be suitable for climbing, but designed mainly to carry keys.

In order to achieve a beautiful contrast, I want to make the pin/rivet of the carabiner out of copper.

Would that create a problem with the longevity of the carabiner? Is copper not strong enough to sustain the everyday use of a carabiner keychain?

Best,
Panos

 

[panosjapan]

kingnero makes a very good point. If you're making these in the U.S. and you don't want all of your profits to fund some injury lawyer's vacation home, you might have to ruin your design with that silly warning.

dwallace1971 and kingnero, thanks for the heads up, but besides not making the carabiners in the US, I've also seen a carabiner that can be used only as a keychain which is made in the US and is of a US company, and doesn't have the warning on the carabiner, but written only in the packaging and at their website, which doesn't hurt the carabiner's design in any way. I'm not sure if someone could have a case against them.

 

[TVP]

panosjapan,

The following link shows the variety of colors that can be obtained with different copper-based alloys. Figure III-4. Lots of options from copper to pink/salmon to yellow/gold.

http://www.copper.org/publications/pub_list/pdf/A4039-ArchitecturalApplications.pdf

 

[panosjapan]

The following link shows the variety of colors that can be obtained with different copper-based alloys. Figure III-4. Lots of options from copper to pink/salmon to yellow/gold.

http://www.copper.org/publications/pub_list/pdf/A4...

Hi TVP. Thank you very much for posting this. It's incredibly helpful. I have one newbie question:

I'm trying to figure out which of those alloys shown in the .pdf are too soft to be used to make a carabiner pin and which aren't. I assume that the two kinds of strength, tensile and yield, are what matter. Is that right? If yes, do both play an important role or one of the two?

Also, what should the number be? I know that brass is a metal hard enough to be used to make a pin and the alloys that include brass in the .pdf have an over 50 tensile strength. Does that mean that the alloy that I'll choose must have an over 50 tensile strength? Or I don't know what the hell I'm saying?

Panos

 

[EdStainless]

Yield strength is where you bend something and it takes a set, Tensile (or ultimate tensile) is where it breaks.
If you make this 'biner correctly then the pin will only be loaded in shear, it can't be bent. In that case just look at the ultimate tensile strength.
My gut feel is that you are about right with 50,000psi for a strength.

How strong is the material for the body?
In that part the yield strength will matter since it could be bent.

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Plymouth Tube

 

[tbuelna]

The carabiners I've seen that were used as keychains were usually anodized aluminum. And they typically used a steel spiral ring to attach the keys, since the hole in the key was normally too small to fit the carabiner body thru.

If aluminum is strong enough for a carabiner key chain body, then any copper alloy should also work. Copper should not need any surface coating. Just the rubbing it experiences in your pocket will put a nice patina on its surface.

 

[kingnero]

@Ed, in shear, he'll need ultimate shear strength. Don't know what it is for Cu alloys, but I'd take around 57% of ultimate in analogy with steel.

 

[panosjapan]

Yield strength is where you bend something and it takes a set, Tensile (or ultimate tensile) is where it breaks.
If you make this 'biner correctly then the pin will only be loaded in shear, it can't be bent. In that case just look at the ultimate tensile strength.
My gut feel is that you are about right with 50,000psi for a strength.

How strong is the material for the body?
In that part the yield strength will matter since it could be bent.

EdStainless, got it about the tensile strength.
The carabiner is made of Zinc alloy. We didn't care much about its strength because it was our intention from the beginning to make it for use as a keychain and not suitable for climbing. I wanted to do it in Stainless Steel, but the cost of the mold for this material was much more expensive compared to a mold for a zinc alloy carabiner. But I'll definitely see what its yield strength is.

If aluminum is strong enough for a carabiner key chain body, then any copper alloy should also work. Copper should not need any surface coating. Just the rubbing it experiences in your pocket will put a nice patina on its surface.

Hi tbuelna, yes, but we are talking about the pin of the carabiner. Could it be possible that the pin in the photo you attached is made of stainless steel? About the coating, yes, we don't intend to do any treatment on the pin, that's why I wanted to use copper and take advantage of its unique color.

@Ed, in shear, he'll need ultimate shear strength. Don't know what it is for Cu alloys, but I'd take around 57% of ultimate in analogy with steel.

Since brass has been deemed as a hard enough material, I'll check its tensile strength and use it as a guide for any future metal choice.

Guys, thank you all for the information. I'll post updates of my project for you to take a look at it if you want.

Best,
Panos

 

[tomwalz]

Have you tried a jewelry forum somewhere?



Thomas J. Walz
Carbide Processors, Inc.

http://www.carbideprocessors.com

Good engineering starts with a Grainger Catalog.

 

[panosjapan]

Have you tried a jewelry forum somewhere?

Never crossed my mind. That's a great suggestion. I'll google for jewelry-making forums. Thanks, tomwalz!

 

[IRstuff]

Somewhat crass, but I have a carabiner that was attached to a promotional zipbag, and the carabiner is stamped in relatively large letters

NOT FOR CLIMBING

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[panosjapan]

Somewhat crass, but I have a carabiner that was attached to a promotional zipbag, and the carabiner is stamped in relatively large letters

Thanks for your reply IRstuff. I'm sure we can find examples in both cases. I've been noticing many carabiners not suitable for climbing without a warning written on them since the forum brought this matter up, so I think I'll take my chances.

 

[dgallup]

I think if it is small enough you are pretty safe. But then I never thought anyone could win a law suit for spilling hot coffee on themselves.

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[IRstuff]

The carabiner I was referring to is about same across the long dimension as pictured above, but the print spans the entire diameter of one leg, in the same spot as shown in the promotional carabiner picture above.

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[panosjapan]

I think if it is small enough you are pretty safe. But then I never thought anyone could win a law suit for spilling hot coffee on themselves.

Idiocracy.

The carabiner I was referring to is about same across the long dimension as pictured above, but the print spans the entire diameter of one leg, in the same spot as shown in the promotional carabiner picture above.

Thanks, IRstuff. I'll take a deeper look at the whole matter.

 

[btrueblood]

There is a Wikipedia article on "carabiner" that discusses the topic. It does state that 'biners intended for climbing are mandated in Europe to have a load rating on them, and similarly for certain uses in the U.S. It would take a pretty naïve climber to use unrated equipment...

 

[panosjapan]

There is a Wikipedia article on "carabiner" that discusses the topic. It does state that 'biners intended for climbing are mandated in Europe to have a load rating on them, and similarly for certain uses in the U.S. It would take a pretty naïve climber to use unrated equipment...

That will make me sleep better tonight. Thank you, btrueblood!

 

[IRstuff]

I don't think that it's the people that would even read a load rating are the ones that you need to be worried about. Not to mention kids...

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[panosjapan]

I don't think that it's the people that would even read a load rating are the ones that you need to be worried about. Not to mention kids...

IRstuff, thanks for bringing this subject up in the first place. It was something worth looking into it. But I have been seeing for the last couple of days so many carabiner without a warning on them, from big and small companies, that I'm led to believe that it won't be a problem.

 

[btrueblood]

"Not to mention kids"

Right, because it's certainly not the parent's job to make sure their kids are not rapelling off the neighbor's roof with un-rated climbing gear.

To be somewhat fair, IRstuff's cautions are probably appropriate for the litigious US market, at least if a supplier intends to be in business for awhile. The reference to idiocracy was an appropriate one, and that movie seems more prescient every day.

 

[panosjapan]

To be somewhat fair, IRstuff's cautions are probably appropriate for the litigious US market, at least if a supplier intends to be in business for awhile. The reference to idiocracy was an appropriate one, and that movie seems more prescient every day.

I agree. The McDonalds example certainly calls for caution. Anyway, moving on..