Steel and Aluminum

[treegazer]

How important is it to keep all metal connections in a climbing system the same?
Should I avoid steel carabiners on aluminum rings or pulleys?
What are the consequences to mixing these metals in a climbing system?

 

[NickfromWI]

I don't mind combining on that combo. With regular inspection, you'll catch anything before it becomes a problem.

love
nick

 

[Blinky]

I can see no incompatibility with biners and rings. Lots of aluminum devices have steel pins and springs.

 

[Tom Dunlap]

This is another myth that has perpetuated itself. Like any myth there is a kernel of truth that is morphed into something completely different.

In a climbing system the pieces are always moving. The wear is spread out over the whole surface area. There isn't any sort of constant point contact for the harder metal to wear the softer one.

Like Nick said, you'll notice any wear during your routine inspections a long time before there is a danger.

 

[Ron]

[ QUOTE ]
How important is it to keep all metal connections in a climbing system the same?
Should I avoid steel carabiners on aluminum rings or pulleys?
What are the consequences to mixing these metals in a climbing system?

[/ QUOTE ]
Actually, steel biners with pulleys is probably a good idea. Many pulley side plates are either thin steel or a bit thicker AL. In either case, as force is applied to the pulley, the thin side plates will cause a concentrated force on the biner.

OTOH, using AL biners with steel pulleys would probably wear a groove in the softer AL biner.

Regarding steel biners on AL rings, The contact area is 'softer' and would not wear as fast as AL on steel pulleys.

But, anytime you put a harder metal against a softer metal, the harder metal will sustain less wear than the softer metal. But, even so there would be possibly the very same wearing effect with AL to AL, except both AL parts would wear essentially equally.

My only caution, as I stated previously, is avoid AL biners with steel pulleys - at least the steel pulleys with thin side plates. Not only is it a hard metal in contact with a softer metal, the force is quite concentrated by the thin side plates. Further, the 'corners' formed by the stamping process can exacerbate the situation.

 

[moss]

If you use a small steel delta screwlink to attach your life support tether to a Petzl Ascension ascender or any stamped aluminum frame ascender you'll notice that over time it will cut into the frame. That's one reason why I like to use a soft attachment (sling) girthed to the ascender. The wear is transferred to the sling but that's something you can inspect and replace as needed.
-moss

 

[Ron]

[ QUOTE ]
If you use a small steel delta screwlink to attach your life support tether to a Petzl Ascension ascender or any stamped aluminum frame ascender you'll notice that over time it will cut into the frame....
-moss

[/ QUOTE ]
Yep, I've noticed that as well. And, the heavier the load, the faster the effect.