Wire Rope Tensile Strength – MBS:
The Wire Rope Tensile Strength of wire is reported in terms of Minimum Breaking Strength (MBS). Each batch of wire is graded or certified at a specified MBS and the batch will meet or exceed the rating. It achieves this rating based on destruction testing. In general – every batch will exceed its rating by some amount. This is done for safety purposes.
Please note that MBS is NOT the safe working load (SWL) or maximum working load (MWL) that the wire is rated at for a given purpose. Basically, the SWL depends on the MBS and a safety factor chosen by the Design Engineer. A further explanation of the SWL is available HERE.
The MBS of a wire depends on the:
- base material (e.g. galvanised vs stainless);
- grade (e.g. 316 vs 304)
- structure (e.g. 1×19 vs 6×36)
- core (e.g. FC vs IWRC)
- Lay (e.g. RHOL) and
Three common wire strand constructions are:
- 1×19 indicates 19 thin wires twisted together in a silky and therefore smooth finish. Consequently, 19 individual wires twisted together construct a single strand of our premium wire. This is the least flexible wire structure. As a result, it is the easiest to keep clean.
- 7×7 indicates a collection of 49 individual wires grouped as 7 sub-strands of 7 wires each. Consequently, 7 wire bundles twisted together form a single strand. This is more (medium) flexible wire than 1×19. As a result, it is for ‘general purpose’ applications and is most economical because it is commonly available.
- 7×19 indicates a collection of 133 individual wires grouped as 7 sub-strands of 19 wires each. Consequently, 7 wire bundles of 19 wires twisted together form a single strand. This is our most flexible wire for use in rigging or small cranes or winches rather than balustrade construction. Low Cost Wire does not recommend 7×19 wire for balustrade construction.
…In conclusion, the more wires twisted to make a strand, the more flexible is the strand of wire because it deforms/bends without damage. More details are also available Here