In reply to Ty:
Just a short mail to try and correct some inaccurate posts on this thread.
The type of alloy used on nuts and the treatment the alloy receives is very important, especially on the small nuts. DMM¡¦s small nuts are forged from 7075-T6 because this has both a high tensile strength and is relatively hard. The common 6000 series aluminium alloys ¡V 6061-T6 and 6082-T6 - do not come close to giving the same tensile strength or hardness.
„h 7075-T6 gives typically 505-570 Mpa Tensile and 170 hardness on the Vickers scale
„h 6082 ¡VT6 gives typically 320-340 Mpa Tensile and 100 hardness on the Vickers scale
„h 6061-T6 gives typically 310-330 Mpa Tensile and 95 hardness on the Vickers scale
The real life result of using a weak, soft alloy on small nuts is that the placements will pull through.
7075-T6 is expensive, but it does the job properly - just compare the strengths of the small units between the 3 brands. The DMM and Wild country units are twice as strong and then factor in that the DMM and Wild Country also use a 3-sigma quality control system when rating their products.
The larger DMM and WC units use 6082-T6, because on these sizes the large surface area of metal in contact with the rock allows the use of a softer metal and here the softer metal has advantages because it bites well when loaded.
There are several other ways of cutting costs on nuts; you can keep the shape simple and reduce the number of cutting/CNC operations, but the simpler wedges just don¡¦t fit as many placements; you can reduce the time in the rumblers, but the product ends up with sharp edges that catch when you try and place the nut; you can use a thinner wire, but the larger units then wobble around as you try and place them at full reach and the placement becomes hard to make.
Then we go out of our way to add cost by using a large, but super-safe crimp to the wire. We also CNC a groove in the middle of the nut, but this allows further placement options.
This is why DMM nuts are more expensive.
Regards
Simon Marsh
DMM International