Why do drag chain cables have to use multiple strands of fine copper wire twisted conductors?

2026-07-27 17:27:03

In dynamic cables, the design of the conductor structure directly determines the flexibility, fatigue resistance, and conductivity of the cable. And 'multi strand thin copper wire twisting' is the key technology to cope with this extreme sports environment.

1. Improve flexibility: The finer the fine thread, the easier it is to bend

Although a thick copper wire has strong conductivity, its rigidity is extremely high, and it is prone to stress concentration and fracture when repeatedly bent. In contrast, multi strand thin copper wire has the following advantages:

Single diameter small (usually 0.1mm~0.3mm), small bending radius, can easily adapt to small radius drag chains

There are many filaments (commonly 12 strands, 18 strands, 32 strands), and the overall structure is softer, rebounding like a "spring"

During the repeated bending process, each filament supports each other, disperses stress, and avoids localized concentrated damage

Analogous explanation: Just like a rubber band is easier to bend than a wire, multiple strands of thin copper wire are like countless tiny "flexible springs" stacked together, maintaining conductivity and excellent bending adaptability.

2. Enhance fatigue resistance: disperse stress, extend lifespan

In robot joints, cables may bend thousands of times per minute. Under such frequent stress, traditional solid conductors can develop microcracks, ultimately leading to fracture.

The multi strand thin copper wire structure has a natural "stress dispersion" ability:

Each filament independently bears partial bending force, without forming a single weak point

The slip and slight deformation between filaments can absorb energy and reduce impact

Experimental data shows that under the same bending conditions, the fatigue life of multi stranded conductors can reach 3-5 times that of solid conductors

Data support: Internal testing by Sum Wai shows that after simulating 100000 joint movements of a robot, the cable with 18 strands of thin copper wire twisted conductors has a conductor integrity rate of up to 98%, while only 62% of solid conductors remain.

3. Maintain good conductivity and heat dissipation performance

Although the multi strand structure appears to be "dispersed", its overall conductivity does not decrease, but rather improves:

Fine copper wire has a smooth surface and a large contact area, effectively reducing contact resistance

Multi strand structure forms a "conductive network", even if individual filaments are damaged, the remaining parts can still maintain conductivity

Better heat dissipation capability to avoid insulation layer degradation caused by local overheating

Especially suitable for scenarios that require high signal integrity, such as servo motor feedback signals and encoder circuits.