Breaking strength is affected by use such as bending, metal wear and fatigue, as well as its working environment and storage conditions. Use and abuse may result in damage such as crushing, peening, kinking, and bird-caging, which affects service life. Breaking strength is not considered safe working load (SWL) limit. The factor of safety is the margin of safety between the applied tensile forces (stress) and breaking force of the wire rope. SWL of a wire rope defines the load that can be safely applied, allowing the rope to provide appropriate service and life. In wire rope selection, common safety factors and maximum safe working loads are considered, and precise working and use requirements are determined in machine user's manuals, in accordance with federal regulation.
Generally, minimum acceptable wire rope strength is a breaking strength that is lower than the nominal (published) strength. The wire rope industry developed specific tolerances to offset common variables such as surface wear and metal fatigue. A wire rope manufacturer designs wire rope to this value, which should be considered when making design calculations.