Analysis on process control requirements of 6 and 7 types of cables

Category 6 cableAndClass 7 CableIn order to meet the requirements of domestic and foreign standards, enterprises should work hard to control the process.

(1) insulation process

The elongation of copper wires should be controlled stably within ± 2%; the diameter fluctuation range of wires should be ± 0. 002mm; the fluctuation range of Insulation Outer diameter is ± 0. 01mm; the concentricity is greater than 96%; the coaxial capacitor is limited to ± 1. 5 PF/m; stable and appropriate conductor preheating temperature to ensure good adhesion between copper wire and insulation layer; 7 kinds of foam material should be even, gas injection pressure change, screw rotation change, the tension variation of the discharge line should be as small as possible, and the bubbles in the foam layer should be even and fine-grained, so that the equivalent dielectric constant of the insulation on the whole single line should be kept uniform and consistent.

The adhesion between the wire and insulation is one of the main factors affecting the return loss. The preheating temperature of the wire should be controlled, and the wire should be bright and clean before extrusion. There should be no water, oil and other dirt, segment cooling should be performed after extrusion to ensure the adhesion is controlled within the scope specified by the process.

The material quality and proportion of masterbatch should be strictly controlled. inferior masterbatch not only increase the single-line breakdown point, but also cause low insulation layer strength, no wear resistance, and easy damage; adding too many masterbatch will affect the return loss of the cable. Therefore, we need to select high-quality masterbatch. The added single-line color can be distinguished for identification, not too deep. To reduce the adverse effects of masterbatch.

Choose high-quality insulation materials and reasonable process parameters to ensure smooth and round surface of a single line, to prevent the single line from wear and tear caused by the friction of the single line surface.

(2) Twisting Process

The pitch of the twisted pair of the six types of cables is 8 ~ The pitch of the twisted pair of 16mm and 7 cables is between 20 and 20mm ~ 40mm. When the design line is equal to the pitch, the pitch difference between adjacent lines should be as big as possible. The pitch of adjacent and similar lines should not be an integer multiple.

The twisting process mainly controls the distribution line tension and the bending radius of a single pair line. The tension of a single line and the tension of the pair line should be consistent uniformly, prevents the occurrence of a line from slightly bypassing the other line. It prevents periodic damage and severe deformation of the insulated single line at the twisted pair node. The bending radius of a Single-to-line must be greater than 50mm to prevent instability of the single-to-line structure.

The twisted pair machine must be twisted to improve the electrical performance caused by the eccentric and uneven insulation layer. Currently, there are two main types of twisted pair machines: zero backend and partial backend switches. When the zero-return twisting machine is in the twisted pair, it is only two-wire twisting and the single line itself does not turn, so the single line is not damaged, basically will not affect the return loss value of the cable. Some of the backend twisted pairs are pre-twisted to the first single line in the reverse direction. Because the single line is subject to two reverse directions, the single line will be subject to different degrees of damage, so the torsion rate is generally controlled at around 30%, the maximum should not exceed 50%.

The pitch tolerance of the twisted pair is limited to ± 0. 5mm. The symmetry between the two wires is different from the axial distance, which must be kept unchanged during production to prevent torsion asymmetry. The tension variation range of the shielding tape in the process should be less than or equal to 10% for Category 7 cables. Equal compression must be used to shield all twisted pair wires.

(3) Cabling Process

Active cabling device with tension feedback control should be used to ensure the consistent tension of the pair line on the entire cable length. The reverse tension of the four pairs of cables is constant to ensure the excellent geometric performance of the cables and the pitch remains stable.

The core symmetry must be ensured during cabling, and the line position is relatively fixed. The cable production pitch is generally between 100 and ~ 150mm. The cables have a great influence on the crosstalk, and the pitch is too large. After the cable is bent, the Return Loss and Characteristic Impedance will be affected. The pitch is too small to increase the capacitance and attenuation of the cable.

The purpose of cable Twisting is to prevent the core line from being twisted, so that the structure and performance indicators of the twisted pair line are affected, so that the pitch and shielding of the twisted pair line will not change when the cable is formed, therefore, cable torsion is an effective way to improve Cable Transmission Performance. In the whole process of cable formation, the extended tension of the twisted pair line should be kept within ± 10%, and the bending radius of the twisted pair line should be greater than 75mm, so as to ensure the stability of the cable core structure and the performance will not deteriorate.

When the seven types of cables are shielded with aluminum foil, the tension of the shielding tape in the process should be kept constant to prevent periodic fluctuations, and the change range should be less than or equal to 10%. During the shielding process, a proper mold size should be designed to make the aluminum foil fit. In order to ensure the stability of the cable transmission performance, because the aluminum foil coating is not tight, when the cable is bent, the shielding layer is prone to gaps, affecting the transfer impedance and shielding performance of the cable; aluminum foil coating is too tight, it will affect the capacitance and insertion loss of the cable. The tension and weaving density of the braided copper wire should be effectively controlled when the copper braided shielding is used. The bending radius of the cable core should be greater than 150mm.

(4) jacket Process

The mold should be properly configured to ensure proper tightness of the jacket, uniform outer diameter of the jacket, and no tightening of the six kinds of cable sheath. The tight jacket will cause the line to be deformed under pressure on the insulation layer, affecting the transmission performance; the outer jacket of the seven types of cables should be closely connected to the shield layer to prevent the cables from deformation when being subjected to external force. As a result, the relative position of the midline pair of the cable core is changed, and the transmission performance is bound to be affected. The adjustment of the cable tension is critical. The cable tension is too tight, so that the cable is flattened and the core of the cable is deformed. The properties of the finished product, such as the characteristic impedance and return loss, will be affected to varying degrees.