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Cable coiling terminology

At SIMECH, we use the term “cable coiling” internally, and we are unsure how other wire manufacturers refer to this process. Sometimes, you might encounter the terms “wire spiraling,” “spiral wire,” etc. It seems that there was a need to describe the process of converting straight wires into spiral-shaped ones, and this terminology stuck. Therefore, both we and our customers use the terms “spiral wire” and “spiraled wire” interchangeably, deriving the adjective from this verb.

Cable coiling process

You can find many DIY guides and YouTube videos on “How to Make a Spiral Cable” at home. Hobbyists attempt to make spirals from USB charging cables and other wires not meant for this purpose by wrapping them around a pencil and heating them with a hairdryer. The results are usually mediocre, and the “spring” is not tight and loses its shape because not every wire can be made into a spiral.

Cables for coiling

Spirals can be made from stranded wires because solid wires, once deformed (stretched out of the spiral), would not return to their previous shape. Most commonly, these are multi-core cables, though single-core wires can also be used if necessary. The key is the appropriate material of the cable jacket, which, during heating, becomes plastic enough for the polymer to reorganize its cross-linking and retain the shape, while also maintaining the proper wall thickness and not sticking to the core insulation. After heating the spiral, the jacket must be removed, and the cores insulated, which would be impossible if the insulations melted together. Harder jacket materials provide greater springiness and stiffness, while softer materials offer greater flexibility, requiring less force to stretch the spiral. Materials such as polyurethanes (PUR) or polyvinyl chloride (PVC) are chosen with specific parameters for different applications.

Long PUR spiral cable and small PVC spiral wire.

SIMECH offers many cables suitable for spiraling (marked with an icon )

String spirals

We also produce spirals from Kevlar, polyester, or cotton strings coated with polyurethane. These are not, of course, electrical wires, but due to their mechanical properties, the spirals are used in the construction of “motorcycle tethers” (emergency kill switches for motorcycles, ATVs, boats, and snowmobiles) and for securing firearms in the military and police.

Spiral winding

The spiral, or rather the helix (Helical line), shape is given by winding the wire around a rod and fixing it through heating. This is important because the length of the coiled spiral is limited by the length of the rod on which it must be heated in its entirety. Thus, spirals cannot be produced in continuous lengths, but this is not a problem as we have rods up to 1500 mm long. One and a half meters of coiled cable is about 4.5 meters of stretched spiral!

The internal diameter also depends on the rod diameter, which is chosen according to the diameter of the wire to be spiraled. The best mechanical properties are achieved within a certain range of the spiral diameter to wire diameter ratio.

In addition to the coiled part of the wire, cables also have two ends with straight sections, which can be aligned along the spiral axis or perpendicular to it. This depends on how the spiral is fixed to the rod before setting. After heating, which must occur under strictly controlled conditions, and cooling, the product is not yet ready. The spiral, although it has its helical shape, is still quite loose, and the coils do not hold together with the desired force. To achieve the desired properties, the spiral must be rewound.

Spiral control cable

After heating, which must occur under strictly controlled conditions, and cooling, the product is not yet ready. Although the spiral has its helical shape, it is still quite loose, and the coils do not hold together with the desired strength. To achieve the desired properties, the spiral must be rewound.

Spiral rewinding

Rewinding the spiral in the opposite direction to the one previously fixed creates a tension that pulls the spiral together even tighter. This ensures that the individual coils hold together firmly. The principle of this mechanism is similar to a reflex bow. In such a bow, the string is drawn as if in the opposite direction to the natural curvature of the bow, so it is already pre-tensioned even before the string is drawn. Similarly, our spirals are pre-tensioned in the contracted state, so they return to this state more readily after being stretched.

Cable end processing

We process finished spiral wires on-site according to customer orders, so they can be immediately installed as intended upon delivery. We can perform:

  • Stripping of the jacket and core insulation
  • Tinning
  • Crimping of connectors:
    • KZ
    • KZ modular
    • Ring
    • Fork
  • Crimping of:
    • Straight and angled spade connectors
    • Blade terminals
    • Insulated and non-insulated ferrules
    • Micro-plugs: 4P4C, 6P4C, 6P6C, 8P8C
    • Other connectors as agreed with the customer
  • Overmolding of strain reliefs
  • Manufacturing of power plugs “unischuko” as well as Class II power plugs

About spiral cables – technical data