Wire rope is often referred to as a "machine" because when bends the individual slide relative to each other. For this reason wire ropes on running rigging require lubrication. Proper lubrication retards wear and corrosion. A wire rope can have hundreds of separate wires in its cross section. Each wire was made separately at what was possibly a different day. For this reason it is unlikely that a "local" weak area can exist due to a manufacturing error. This characteristic of wire ropes also allows an un-fractured adjacent section to be tested to estimate the pre-fracture strength of a wire rope. Wire ropes fracture because they are loaded in excess of their strength, but their strength can be reduced due to such things as wear, corrosion, or local damage. It is possible for a system to create a load which is greatly in excess of that which was originally intended.