What factors can affect the quality of control cables?

The quality of control cables is influenced by multiple dimensions. From the selection of raw materials to the production process and usage environment, all these links may have a direct impact on their performance, reliability and service life. The following is a detailed analysis of the key influencing factors from a full-chain perspective:

I. Raw material quality: The cornerstone determining the performance of cables

Defects in conductor materials

Insufficient purity: The use of impure recycled copper (such as copper content < 99.9%) or inferior aluminum alloy leads to an increase in resistivity (copper conductor resistivity > 0.017241Ω · mm²/m), severe heating, and even short circuits.

Processing defects: Scratches, burrs, or insufficient annealing (elongation < 25%) occur during the wire drawing process of the conductor, resulting in poor flexibility and easy breakage during wiring.

2. The insulating material is of poor quality

The temperature resistance grade does not meet the standard: Using ordinary PVC instead of cross-linked polyethylene (XLPE), the insulation layer softens and carbonizes in a high-temperature environment (> 70℃), and the voltage resistance strength decreases (for example, the voltage resistance test of a rated voltage 0.6/1kV cable is < 1500V).

Impurities and bubbles: When insulating materials are mixed with impurities or bubbles are introduced during production, the insulation resistance decreases (< 100MΩ · km), increasing the risk of leakage.

3. Defects in shielding and sheath materials

The shielding layer is shoddy: the copper mesh coverage rate is less than 80% or the aluminum foil overlap rate is less than 10%, the anti-electromagnetic interference ability is weak (shielding attenuation is less than 40dB), and the signal transmission is prone to interference.

Poor weather resistance of the sheath: Using recycled materials or inferior PVC, it has insufficient oil resistance and weather resistance, and ages and cracks rapidly in an oily or ultraviolet environment.

Ii. Production process loopholes: Leading to structural and performance failures

1. Defects in the conductor processing technology

Improper twisting: The twisting pitch is too large (> 25 times the diameter of the conductor), causing the wire core to be loose. During signal transmission, the impedance is unstable and the attenuation intensifies (for example, the attenuation of a 1MHz signal is > 5dB/100m).

Poor welding: The conductor joints are not welded firmly or have false welding, resulting in high contact resistance. Long-term operation causes heat generation, leading to wire breakage.

2. The insulation extrusion process was out of control

Uneven thickness: The temperature fluctuation of the extruder is large (error > ±5℃) or the traction speed is unstable, resulting in the insulation layer thickness tolerance > ±0.1mm, and the weak points are prone to breakdown.

Incomplete cross-linking: The cross-linking time of XLPE insulation in warm water is insufficient (< 12 hours), the material has poor weather resistance, and the insulation layer becomes brittle and cracks after long-term use.

3. Defects in shielding and cabling processes

Shielding layer breakage: Improper tension control of the weaving machine, copper wire breakage, resulting in a decrease in shielding layer coverage and failure of anti-interference performance.

Loose cabling structure: Insufficient filling material or inadequate tension of the winding tape, poor roundness of the cable core, and the insulation layer is damaged due to compression during bending.

4. Sheath extrusion defect

Poor plasticization: The plasticization temperature of the PVC sheath material is too low (< 160℃), the surface is rough and has particles, the tear resistance strength is less than 15N/mm, and it is prone to damage.

Excessive eccentricity: The eccentricity of the sheath extrusion is greater than 15%, the local thickness is too thin, and the mechanical protection capacity decreases.

Iii. Equipment and Technical Level: Bottlenecks Restricting Process Accuracy

The precision of the old equipment is insufficient

The temperature control accuracy of traditional extruders is greater than ±3℃, and the resolution of laser diameter gauges is less than 0.01mm. This cannot ensure the uniformity of the insulation layer thickness, resulting in unstable pressure resistance performance.

Low degree of automation

The tension control error during manual wire laying and winding is large, causing the conductor to stretch and deform or relax, which affects the mechanical performance of the cable (such as tensile strength fluctuation > 10%).

Lack of advanced detection equipment

It is not equipped with a partial discharge detector (detection limit > 10pC) or a high-frequency signal analyzer, making it impossible to detect potential insulation defects or signal attenuation issues.

Four. Lack of quality control: A breeding ground for hidden risks

The random inspection of raw materials is not strict

The copper rods were not subjected to spectral analysis (impurity content > 0.01%) or the insulating materials were not tested for thermal elongation (elongation rate > 150%), and inferior materials flowed into the production.

Omissions in process detection

Skipping the inspection of key processes (such as not conducting withstand voltage tests after cabling and not conducting conduction tests on the shielding layer) leads to the release of substandard products.

The finished product inspection is not comprehensive

No aging tests (such as the tensile strength retention rate < 80% after aging at 70℃×168h) or flame retardant tests (failing the GB/T 18380 bundle burning test) were conducted, making it impossible to verify the reliability of long-term use.

V. Unreasonable design and selection: Insufficient adaptability leads to malfunctions

Parameter matching error

In high-frequency signal scenarios (such as PLC control), unshielded cables are selected, or the shielding structure is wrongly chosen (such as not using copper mesh weaving in low-frequency interference scenarios), resulting in signal distortion.

Lack of environmental adaptability

In high-temperature environments (> 100℃), silicone rubber insulated cables were not selected, and in low-temperature environments (< -20℃), cold-resistant sheaths were not used, resulting in material hardening and cracking.

Structural design defect

In mobile scenarios (such as drag chains), flexible structures (such as aramid reinforcement + polyurethane sheath) are not adopted, and frequent bending leads to conductor breakage or insulation damage.

Vi. Environmental and Usage Factors: Accelerate performance degradation

Improper storage and transportation

Excessive stacking of cables causes indentation on the sheath, or they are stored outdoors and exposed to ultraviolet rays (UV radiation > 50W/m²), leading to premature aging of the sheath.

Installation violation

If the bending radius is too small (< 6D), the insulation layer will be wrinkled and damaged, or if the tensile force exceeds the rated value (such as the tensile force of copper core cables > 12N/mm²), the conductor will deform.

Overload operation

Long-term operation exceeding the rated current (for example, the current-carrying capacity of a 4mm² cable is greater than 30A) will accelerate the heating of the conductor and the insulation aging (shortening the service life by more than 50%).

Seven. Inconsistency between standards and certifications: No quality guarantee

Production was not carried out in accordance with the norms

The deviation of the cross-sectional area of the conductor is greater than -5% (such as the nominal 2.5mm² but the actual < 2.375mm²), which does not conform to the GB/T 3956 standard and the current-carrying capacity does not meet the standard.

Lack of necessary certifications

It has not passed the RoHS certification (lead content > 1000ppm) or UL certification, and thus cannot meet environmental protection or safety requirements, posing compliance risks.

Viii. Human factors: Uncertainty in process execution

The operator's skills are insufficient

Incorrect parameter Settings of the stranding machine (such as pitch ratio > 25), or failure to calibrate the extruder after mold change, result in defects in batch products.

Weak quality awareness

Neglecting process details (such as insufficient lap of the shielding layer) or omitting inspection steps to meet deadlines has sown the seeds of quality risks.

Comparison table of Key Factors and Influencing Consequences

The categories of influencing factors, the direct impact of specific issues on cable quality, and typical failure scenarios

Defects in raw materials: impurities in conductors, insufficient temperature resistance of insulating materials, increased resistivity, insulation breakdown, short circuit in high-temperature environments, and signal transmission interruption

The production process has loopholes, such as uneven thickness of the insulation layer, breakage of the shielding layer, decreased withstand voltage strength, failure of anti-interference ability, breakdown in high-voltage environment, and maloperation of the equipment caused by electromagnetic interference

Design and selection errors include not choosing oil-resistant sheaths, improper shielding structure with sheath cracking, signal attenuation, sheath swelling in an oily environment, and signal distortion in industrial sites

Environmental and usage violations: The bending radius is too small, insulation is damaged due to long-term overload operation, conductors heat up and age, insulation is damaged during installation, and cables burn out after long-term operation

The quality control was lacking and no aging test was conducted. The shielding conduction test was omitted and the service life could not be verified. The shielding layer failed and the cable aged prematurely. The anti-interference performance did not meet the standards

Summary

The quality of control cables is the result of the combined effect of multiple factors such as raw materials, processes, equipment, design, control and management, and the usage environment. Any oversight in any link may lead to a decline in electrical performance (such as insulation resistance, shielding attenuation), mechanical performance (such as bending life, tensile strength), or environmental adaptability (such as temperature resistance, weather resistance). To ensure quality, it is necessary to control the quality of raw materials from the source, optimize the precision of production processes, improve the full-process inspection, and rationally design and select models based on application scenarios. At the same time, standardize the storage, installation and usage processes.