Why are the staples used with cardboard boxes copper plated? Rust prevention doesn’t seem like a good reason since cardboard isn’t strong when wet.
Waxed cardboard boxes are plenty stong when wet. So it could be for those, and they just use the same ones for everything else?
Copper seems an odd choice for rust prevention. Copper oxides, too. Nails and screws, conduit, etc., are galvanized with a coating of zinc for rust prevention. I imagine they’d use copper if it were cheaper.
My guess would be that box staples are just wire cut to length and turned into a staple, and copper is easier to form into the right sized wire because of its ductility. The staple machines are probably fed by a giant spool of copper wire.
The ones I have removed are steel, plated with copper. A magnet picks them up, and they are far harder to bend than an equivalent sized piece of 12 gauge copper wire.
Just venturing a guess. Copper oxidizes slower and typically less than steel in the same environment. And the copper “rust” is less messy than steel rust.
I think you’ve got it. Most shipping departments aren’t humidity controlled environments, and a box of staples which grows a coating of rust would tend to foul the stapling machine over time.
I must say, this is a splendid question! I never gave it a thought before, but now that you mention it, it is a curious state of affairs.
Here’s my hypothesis. Some metals are naturally “greasier” than others – that is, they slip against other metals more smoothly. I think bronze and brass are noted for this quality. My guess is that copper is too. When the staple gets formed by the …err… stapler, I’m pretty sure it rubs along a sort of bent finger to curl back on itself. My theory is that the copper coating helps the staple prongs glide along the these fingers with no hang-ups and putting less wear on the mechanism.
In any case, I’ll pass this question along to a friend who works for a copper industry trade group. Maybe somebody there knows for sure.
This is correct, but it is not just the stapler, the flash of copper also cuts down wear on the drawing and forming dies used to manufacture the staples.
The corrosion angle is also correct, and related. Rust on the staples might cause enough friction to jam the stapler, and iron oxide is an abrasive that will greatly increase wear. Rust forming under the glue that holds the stick of staples togethor will also cause them to come apart and jam. Keep in mind that these staples might sit in thier boxes for years before being used.
So, does anyone know the typical copper content of copper-plated staples?
Great question, and it seems surprising that they are. The needs to be lubricious and resist corrosion are both common enough, but I can’t think of any other product made of copper plated steel.
Kevbo, can you elaborate?
there is copper coated steel wire for use where you need the strength of steel and the surface conductivity of copper.
copper forms a protective oxide where iron forms a destructive oxide. copper plating of staples does have a corrosion protective effect.
This, and what Stuyguy said. If corrosion was the intent, they would use zinc (galvanize). Zinc is sacrificial to iron, so it protects the iron from rusting. Iron is sacrificial to copper (which is why you don’t see the copper coating turn green), so it actually accelerates the rusting.
The “staple” is a wire strip prior to being stapled into the box. The staple machine cuts it to length,bends the wire to staple shape, punches holes in the box to insert the forming ‘prongs’ (that is why you always will see two holes, one on either side of the staple, where these are used) and pushes the staple through the box where the forming ‘prongs’ bend the ends back to the middle. There is a lot of pressure of the staple against the metal parts (formng dies). The copper prevents galling between the steel staple and these dies; and it only takes a very thin layer. Zinc would wear off and build up–leading to the aforementioned jams.
excavating (for a mind)
e.g. the center conductor of a lot of RG-6 coaxial cable.
The steel wire used in Metal Inert Gas Welding is always copper coated, both the easier to from and lack of corrosion are valid reasons, that being said stainless or aluminum MIG wire is uncoated.
Steel fasteners for drawn arc welding are also usually copper coated. Same goes for certain resistance projection fasteners when used for grounding applications.
This fact doesn’t preclude it’s use in corrosion protection. Zinc diecast is usually copper nickel chrome plated. I’m not saying that’s the purpose here, I’m just stating that the coating is not always sacrificial.