Aluminium Ferrules (large)

These small, thick aluminium tubelets look like a metal fig roll that has lost its filling. They are wire rope ferrules that can be squeezed onto galvanized steel wire ropes to create strong, permanent loops or ‘eyes’, from which light to medium loads can be hung (think light fittings or clothes lines). The ferrules are positioned in place on the wire rope and then crimped (squashed) to tighten them around the wire using a special hydraulic crimping tool called a hand swager.

The use of malleable pieces of metal to join tool together or reinforce them has its roots in the Bronze Age, when soft copper alloys (bronzes) were used to cap and reinforce wooden spears or staffs, or to join together pieces of ceremonial objects like the elaborately decorated Late Bronze Age flesh-hooks, found intact in Irish bog deposits and thought to have been used in feasting rituals. 

The word ferrule has been traced back to the Medieval Latin word for small bracelet or little ring and the Old French word for collar. These little metal collars are used to join all manner of things: they bind horsehair to wood on violin bows, join together the segments of telescopic fishing rods, make water-tight connections possible in hoses and tubing, and cap the top of an umbrella to stop the canopy sliding off the end. We also have some paintbrush ferrules in our collection, which are used to join the hair bristles to the handle in artists’ and decorators’ brushes.

Aluminium is excellent at being a ferrule because it is so ductile, malleable and formable. This trio of properties all describe slightly different ways in which aluminium can be deformed without cracking or breaking: it can be drawn into long thin wires, can be compressed by flattening, hammering or rolling, and can be shaped in multiple directions at once without breaking. 

In the grand scheme of materials, all metals are relatively malleable and ductile, but the extent to which they can be deformed depends on their crystal structure. At the microscopic level, metals are made up of lots of tiny crystals, called grains, which are tessellated together in a pattern that looks a bit like crazy paving. When you casually bend a paperclip or push a chunk of aluminium through an industrial hydraulic press, you are forcing these tiny grains to stretch, deform, and slide past one another. Different metals are more or less strong, brittle or ductile because of how easy or hard it is for these grains to slide, rotate and rearrange themselves without the material breaking. Aluminium’s grains are better at deforming than, say, tungsten’s, but neither metal is as malleable as lead, whose grains deform so easily that you can bend thick pieces by hand, dent it with your fingernail, and roofers can cut it with a knife. Want to read more about malleability in metals? Check out our aluminium armature wire.

The manufacturers warn that these aluminium ferrules should only be used with galvanised wire rope, and never with stainless steel cable. Aluminium is pretty corrosion-resistant: as soon as it is exposed to air, it readily reacts with oxygen to form a protective aluminium oxide layer that is hard and impenetrable to many harsh industrial chemicals. However, the presence of stainless steel can cause the aluminium to corrode faster than it normally would, in a process called galvanic corrosion. When two dissimilar metals are in contact with each other in a humid environment, this forms an unintentional, primitive electrical battery, which causes the less ‘noble’ (more reactive) of the two metals to corrode. When the wire is galvanised, it is coated with a protective layer of zinc, which is electrochemically similar to aluminium and way less likely to prompt galvanic corrosion.To read more about galvanic corrosion, see our aluminium wool.