Concentric strands
In concentric strands, the individual wires are subject to an exact positioning around a core wire, which ensures an all-out uniform structure.
Applications
- Extrusion: thin-gauge coating with high-grade isolation materials
- 7-end strands are particularly suited for data cables with high frequencies of transmission
Particular benefits for our customers
- Uniform elongation of single wires
- Low tolerances, even in single wires (even outperforming ASTM)
Manufacturing range
- Materials: Cu-ETP1, Cu-OF1 and LEONI Histral® alloys
- Bare, tin-plated, nickel-plated, silver-plated
- Left-hand lay or right-hand lay
- Variation: soft annealed
- Single-wire diameter: ranging from Ø 0.05 mm to Ø 0.51 mm
- Cross-section: ranging from 0.02 mm2 to 630 mm2
The following strand constructions are possible:
concentric strand 7 end
7-end = 1 + 6
concentric strand 19 end
19-end = 1 + 6 + 12
concentric strand 37 end
37 end= 1 + 6 + 12 + 18
More relevant details can be found in ASTM regulation B 354.
7-end and 19-end strands are the preferred choices for cables used in electronics. The precise positioning of the individual wires makes for a smooth and even surface as well as an unvarying diameter.
Construction unilay
Unilay concentric
- same lay direction
- same lay length
- manufactured in one working step
- nearly round construction (hexagonal)
Unidirectional concentric
- same lay direction
- different lay lengths for each working step
- manufactured in two working steps
- more round than unilay concentric
Direction of stranding
Construction true concentric
Equilay concentric (reversed lay stranding or SZ stranding)
- different lay directions
- same lay length
- manufactured in two working steps
- very round construction
Conventional concentric
- different lay directions
- different lay lengths for each working step
- manufactured in two working steps
- very round construction
Direction of stranding
Reversed lay direction / SZ stranding
S ➔ left hand lay
Z ➔ right hand lay
Strands with the same lay direction are generally called unilay.
Strand with opposing lay direction (SZ stranding) are called true concentric.
The roundness of a strand is driven by its lay length as well:
longer lay length = hexagonal
shorter lay length = more round
Moreover, there is a patented manufacturing process that allows for the production of strands featuring a highly compact and precise round structure: LEONI’s smooth bunches