Armouring Machines Information

 

Figure 1: Power cable. Source: Les deHamer/Unsplash

Armoring machines are used to apply an outer sheath to strengthen cables, flexible pipes and conduits. They enhance the durability, resilience, and longevity of various types of cables, conduits, and pipes and are used in a wide variety of applications.

Applications

In wire and cable manufacturing, armoring machines strengthen cables by applying a metallic outer sheath, typically involving enveloping wires within a metal tube that may be overlaid with plastic insulation. 

Armored cable should be used when cables are buried underground, in outdoor installation, or in tunnels. Armoring provides mechanical protection to cable so that the cable is resistant to higher stresses.

Figure 2: Armored cable. Source: Spinning Spark/CC BY-SA 3.0

Power

There are three types of metal shielded electrical cables — braided, served, and foil — all fabricated similarly. The process begins with a wire bundle core composed of insulated copper wires. Next, a metallic cover is added, generally by winding a metal strip around the core, giving the shielded cable a corrugated appearance.

Flexible conduits are metallic tubes designed to protect electrical wires. Armoring machines for these conduits work by coiling metal strips into an interlocked, circular metallic tube, resulting in an armored flexible conduit, similar in appearance to armored cable.

Standard power cables may be aluminum wire armor (AWA) or steel wire armor (SWA). Steel offers more strength however for single core cables, AWA is used. If a single core cable has SWA, a magnetic field is created when current flows through the cable. Larger currents will create larger magnetic fields that will induce an eddy current in the steel armor resulting in overheating and derating. Since aluminum is not magnetic, this issue is not presented. In cable with two or more cores, steel wire armor can be used as the magnetic fields have a cancelling effect.

Figure 3: Fiber optical cable. Source: Pixabay

Oil and Gas

Flexible pipes are used in the oil and gas industry. They are corrosion-resistant and withstand high pressures and tensile loads. The armoring machines for flexible pipes operate by winding a metal strip around the pipe, adding a protective layer.

Types of Armoring Machines

There are a variety of types of armoring that required different armoring machines. The core function of armoring machines is to apply a robust protective layer or 'armor' that shields these components from physical damage and increases their durability.

https://www.youtube.com/watch?v=HcURqtiT9cw

Video: Armoring machine wire/strip armoring. Source: AEI Machines

Wire

Wire armoring machines are used where cables need to withstand extreme conditions. These machines work by winding individual metal wires around the cable to create a robust and flexible armored sheath. The result is a highly resilient cable that can withstand high pressures, tensile loads, and corrosive conditions.

The metal wires used in this armoring process are typically made of high-strength materials such as steel or galvanized iron, providing exceptional mechanical strength to the cable. Due to their robust nature, wire-armored cables are commonly used in industries like oil and gas, mining, and marine applications, where cables are expected to endure high-stress environments.

Wire armoring not only enhances the cable's mechanical strength, but it also provides an additional grounding path, improving the cable's overall electrical safety. This grounding functionality is particularly crucial in applications where electrical faults could pose significant safety risks.

Strip

Strip armoring machines are predominantly used for the production of armored cables and flexible conduits. These machines function by continuously applying a metallic strip, commonly made from galvanized steel or aluminum, around the cable, conduit, or optical fibers. The strip is typically helically wound around the core, forming a tough, interlocked armor that provides excellent mechanical protection. Strip armoring machines play a significant role in enhancing the mechanical strength of cables and flexible conduits. 

This type of armor provides a high degree of mechanical protection without significantly increasing the overall diameter of the cable or conduit, making it suitable for applications that require durability and resistance against environmental factors.

Strip armoring is frequently employed in the production of power cables, communication cables, and flexible conduits used in a variety of sectors including construction, telecommunications, and oil and gas industries.

Interlocking

https://www.youtube.com/watch?v=WSrsm_B9OWA

Video: Interlocking armoring machine. Source: Kalmark Integrated Systems

Interlock armoring machines are designed to produce a unique form of cable or conduit protection, known as interlock armoring. This process involves creating a flexible, interlocked metallic sheath around the core of the cable or conduit.

Interlock armoring machines are specialized in producing a unique, interlocked armored sheath, which offers excellent flexibility and bending capabilities. In commercial and industrial buildings, interlocked armored cables are often used for electrical wiring that needs to be routed around corners or through tight spaces. These cables can endure significant bending and twisting without damaging the internal conductors.

Interlock armoring distinguishes itself from other armoring techniques by its distinctive structure and high flexibility. The armoring machine wraps a flat strip of metal (such as aluminum and steel) around the cable in an overlapping, interlocked pattern, creating a continuous metal tube. This interlocking pattern gives the armor its flexibility, allowing it to bend with minimal stress on the cable or conduit inside, while still providing robust mechanical protection.

In addition, interlocked armoring provides excellent crush resistance and tensile strength, making it suitable for use in a wide range of environments. For example, in the oil and gas industry, interlocked armored flexible pipes are used for the transfer of fluids under high pressure in harsh conditions. This type of armoring helps to ensure the integrity and longevity of the pipes, even under mechanical stress.

Basket Weave

The basket weave armoring process employs specialized machines to create an intricate, basket-weave pattern of wires creating a braded outer armor that wraps around the cable. The fundamental principle of this type of armoring is to apply multiple layers of thin, resilient wires across the cable core in a specific, interwoven pattern. This particular configuration resembles the structure of a woven basket, resulting in the term "basket weave" armoring.

Basket weave armoring machines effectively intertwine individual wires, winding them around the cable core in a crosshatch pattern. This method of wrapping wires around the cable in alternating directions results in an armor that can evenly distribute mechanical stresses, enhancing the cable's overall tensile strength and crush resistance.

This type of armoring mechanical protection. The weave pattern offers a high degree of flexibility, allowing the cable to bend without causing damage to the internal components. Simultaneously, the woven structure grants the cable resistance against external pressure, making it suitable for applications where cables may be subjected to high mechanical stress.

One application of basket weave armoring is in the production of undersea cables. These cables must withstand the pressures of the sea, and the potential for damage from marine life or underwater geological activities. 

Kevlar

Kevlar armoring machines can be used to fortify optical fiber cables and other wiring systems. Kevlar is a light synthetic fiber with high tensile strength that provides durability and protection against physical damage. This type of armoring is predominantly used in applications where cables need to withstand high mechanical stress without reducing flexibility. 

Kevlar armoring is used in the manufacturing of robust communication and data transmission cables, particularly in environments where they might be exposed to pulling, bending, or other forms of mechanical stress. The Kevlar sheath not only protects the internal fibers, but it also contributes to the overall tensile strength of the cable, enabling it to withstand substantial mechanical strain during installation and throughout its service life.

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