Audio Cable Extrusion Line

Audio Cable Extrusion Line

An audio cable is a connecting wire used to transmit sound signals between audio equipment. It acts like a "bridge" for sound, carrying signals from a source (such as a phone, computer, or guitar) to a receiver (such as speakers, headphones, or a mixer).
Basic Structure
A typical audio cable consists of the following parts, from the inside out:
Conductor: The core component responsible for transmitting electrical signals. Usually made of oxygen-free copper; the higher the purity, the better the conductivity and the smaller the signal loss.
Insulation layer: Wraps around the conductor to prevent signal short circuits and protect the conductor.
Shielding layer: A layer of metal braiding or foil wrapped outside the insulation layer. It acts like a "Faraday cage" to block external electromagnetic interference and ensure sound purity.
Outer jacket: The outermost layer of rubber or plastic protection, responsible for wear resistance and anti-pulling.

Audio Cable Extrusion Line

An audio cable extrusion production line refers to the entire production system that melts materials like plastic (e.g., PVC, PE) or rubber and uniformly coats them onto a metal conductor (copper wire) to form an insulation layer or a sheath layer. It is the core equipment for manufacturing the cable body of audio cables. Its operation directly determines the cable's insulation performance, durability, appearance, and electrical characteristics.

Core Components

A complete audio cable extrusion production line is a collaborative system, mainly composed of the following major parts, arranged in the order of the technological process:
Pay-off System
Function: Used to place and release bare copper wire (or core wires that have already been insulated internally).
Key Requirement: Tension control must be stable and even. Excessive tension may thin or break the copper wire, while insufficient tension will cause the cable to be slack and unevenly spooled.
Types: Divided into active pay-off (motor-controlled) and passive pay-off (controlled by a magnetic powder brake).
Preheating and Tension Adjustment Device
Preheater: Heats the conductor before it enters the die head. This helps remove moisture from the conductor surface, allows the plastic melt to adhere more tightly to the conductor, reduces internal stress and bubbles, and improves insulation quality.
Dancer Roll/Tension Pulley: Detects in real-time and fine-tunes the tension of the wire, ensuring it remains constant throughout the entire production process.
Core Part: Extruder
Function: This is the "heart" of the production line. It heats solid plastic pellets into a molten, viscous state and continuously and steadily conveys them through the rotation of a screw.
Main Components:
Hopper: Used for feeding plastic raw material.
Screw: The core component, responsible for conveying, compressing, melting, mixing, and metering the plastic. Different screw designs are used depending on the raw material (e.g., PVC or PE).
Barrel: Encases the screw, has external heating bands, and withstands high internal pressure.
Drive Motor: Provides power to the screw.
Die Head and Mold
Function: This is the key component that determines the final structure and appearance of the cable. The molten plastic is precisely coated onto the conductor here.
Mold Types:
Pressure Die: The plastic is pressed directly onto the conductor, resulting in good adhesion. Often used for insulation layer extrusion.
Tubular Die: The plastic first forms a tube shape, which is then sucked onto the conductor under vacuum. Provides a smooth surface, high roundness, good concentricity, and is often used for cables requiring high performance.
Cooling Trough
Function: Rapidly cools and sets the high-temperature cable emerging from the die head.
Requirement: Cooling must be gradual. The trough is usually divided into several sections, with water temperature decreasing from high to low, to avoid internal stress or bubbles caused by sudden cooling.
Spark Tester
Function: An online quality inspection device. It applies high voltage to detect defects such as broken skin or pinholes in the insulation layer. If a defect is found, it immediately alarms or stops the machine, ensuring the product's voltage resistance is qualified.
Caterpillar Haul-off / Puller
Function: The source of "traction" for the production line. It acts like a pair of steady hands, pulling the cable from the pay-off end through the entire production line at a constant speed.
Key Requirement: The speed must be perfectly synchronized with the extruder's output speed. Unstable speed will cause the cable diameter to vary.
Take-up System
Function: Winds the finished cable neatly onto a reel.
Types: Includes active take-up (motor-driven) and passive take-up (pulled by the haul-off). Modern production lines usually use coordinated control to keep the take-up tension constant, avoiding overwinding or loose winding.
Control System
Function: The "brain" of the entire production line. Usually a PLC (Programmable Logic Controller) with a touchscreen interface, used to centrally set and control all parameters:
Temperature: Heating temperature of each barrel section and the die head.
Speed: Screw rotation speed, haul-off speed, take-up speed.
Tension: Tension values for pay-off and haul-off.
Synchronization: Ensures the speeds of all parts are matched.

Production Process

Taking the production of a simple single-core shielded audio cable as an example, the process is as follows:
Pay-off: The pay-off system releases the bare copper conductor.
Preheating and Tension Adjustment: The conductor passes through preheating and tension adjustment.
First Extrusion (Insulation Layer):
Plastic pellets are melted inside the extruder.
Through the mold, the molten plastic is tightly coated around the copper conductor, forming an insulated core wire.
Cooling and Setting: The core wire enters the cooling trough to solidify.
Spark Test: A high-voltage test is performed on the insulation layer to ensure no defects.
(Optional) Stranding: If it is a multi-core cable (e.g., for left and right channels), multiple insulated core wires are twisted together.
(Optional) Braided Shielding: Before the cable enters the second extruder, a braiding machine wraps a layer of metal shielding mesh around the outside of the core wire(s).
Second Extrusion (Sheath Layer):
Another extruder is used to extrude the sheath material (usually more wear-resistant), coating the outside of the shielding layer and core wire(s).
Cooling and Testing Again: After the sheath layer cools, a spark test may be performed again.
Pulling and Take-up: The haul-off pulls the finished cable out with constant tension, and the take-up system winds it neatly onto a reel.
Subsequent Processes: The wound cable is sent to a coiling machine to be cut to specified lengths and may undergo connector termination (e.g., soldering RCA, XLR connectors).

Audio Cable Extrusion Line Datasheet

Model	30	40	50	60	70	80	90
Screw Diameter (mm)	φ30	φ40	φ50	φ60	φ70	φ80	φ90
Screw L/D Ratio	25:1	25:1	26:1	26:1	26:1	26:1	26:1
Extrusion Amount (kg/hr)	25	40	70	100	140	200	250
Outlet Wire (mm)	0.2-1	0.4-3	0.8-5	1-8	2-15	3-25	5-35
Total Power (KW)	18	20	25	33	40	55	63
Traction Power (KW)	2.2	2.2	4	4	4	5.5	5.5
Production Speed (m/min (Max.))	600	600	600	500	500	300	300
Take-up Spool (mm)	φ200-400	φ300-500	φ400-630	φ400-630	φ500-630	φ800-1000	φ1000-1250

Audio Cable Extrusion Line Application

The audio cable extrusion production line is a highly automated and precise electromechanical integrated system. It transforms metal conductors and insulation/sheath materials into finished wires that meet specific electrical and physical standards, and is an indispensable manufacturing cornerstone in the entire audio industry chain. The audio cable extrusion production line is not limited to audio cables, but is also widely used for:
Various cable manufacturing: Headphone cables, microphone cables, audio connection cables, digital coaxial cables, video cables (such as HDMI), power cables, data cables, etc.
Products at different levels: From ordinary consumer grade cables to high fidelity (Hi Fi), professional audio, and even broadcast grade high-end cables, all rely on extrusion production lines. The accuracy and stability of the production line directly determine the electrical performance (such as capacitance, impedance, attenuation) and physical performance (such as flexibility, durability) of the wire.