Anhui Feichun Special Cable Co.,Ltd Email: Li.wang@feichuncables.com

FOMFLEX Festoon: High‑Performance Flexible Rubber‑Sheathed Optical Fibre Cables for Container Cranes, High‑Dynamic Festoon Systems & Heavy Industry

FOMFLEX Festoon is far more than a standard stationary communication cable — it is a purpose‑built industrial optical fibre solution engineered specifically for continuous motion, high mechanical stress, and harsh outdoor environments. Designed by TFKable to operate reliably in festoon systems, ship‑to‑shore cranes, rubber‑tyred gantries, stacker‑reclaimers, and automated material handling equipment, it delivers stable, interference‑free data transmission while lasting two to three times longer than conventional cables. This article explains in detail its construction, engineering principles, material science, full technical specifications, and real‑world performance, including proven applications across key South African ports and mining sites such as Durban, Cape Town, and Richards Bay.

Li.Wang

7/8/202610 min read

Introduction

In modern heavy industry, automation and real‑time control have become essential for efficiency, safety, and profitability. Ports, container terminals, and mining operations rely heavily on moving machinery that travels long distances, operates continuously, and faces extreme environmental conditions. The cables that carry data and control signals between fixed control rooms and moving equipment must therefore do more than just transmit light or electricity — they must withstand millions of cycles of bending, tension, torsion, vibration, temperature fluctuation, and chemical exposure.

This is where the limitations of standard cables become obvious. Traditional fixed‑installation optical fibres are designed to remain stationary; when repeatedly bent or pulled, they develop micro‑bends, increased signal loss, or even complete fibre breakage. Copper cables, on the other hand, suffer from electromagnetic interference (EMI) near motors and variable‑frequency drives, experience voltage drop over long distances, and require frequent replacement due to fatigue.

FOMFLEX Festoon Flexible Rubber‑Sheathed Optical Fibre Cables, developed by TFKable, represent a completely different approach. This product is not a communication cable in the conventional sense; it is a high‑dynamic industrial flexible optical cable designed to serve as both the “nerve” and the “ligament” of moving machinery. Its entire design philosophy is built around decoupling optical performance from mechanical reliability. By using PBT loose tubes filled with thixotropic gel, FRP dielectric strength members, high‑strength aramid braiding, and a specially formulated thermoset rubber outer sheath, it protects delicate glass fibres from stress while supporting high tensile loads and resisting all forms of environmental attack.

This article explains how FOMFLEX works from the inside out, what standards it meets, how it compares to other solutions, and why it has become a trusted choice in South Africa’s demanding ports and mining sectors.

Technical Specifications & Compliance

To understand FOMFLEX Festoon, we first look at its complete technical profile, as documented in the official TFKable specification sheet and aligned with international standards.

General Design Parameters

Fibre count: 2 to 24 fibres per cable
Fibre types: G50/125 µm (OM2), G62.5/125 µm (OM1), or single‑mode G.652 / G.657
Outer diameter: Approximately 10.9 mm
Weight: Approximately 2 kg/km
Standard packing: 1,000 metres on wooden drums; custom lengths available on request
Temperature rating: Fixed installation from ‑40 °C to +80 °C; mobile operation from ‑35 °C to +70 °C
Bending radius: Minimum 15 × D for fixed installation; 20 × D for moving applications
Torsion resistance: Up to 100° per metre
Maximum tensile load: 2,000 N
Maximum travel speed: 250 m/min
Outer jacket colour: Orange for high visibility

Optical Performance

The optical characteristics are critical for maintaining signal integrity over long distances and many years:

Attenuation (multimode): ≤ 3.0 dB/km at 850 nm; ≤ 1.0 dB/km at 1300 nm
Attenuation (single‑mode): ≤ 0.4 dB/km at 1310 nm; ≤ 0.26 dB/km at 1550 nm
Bandwidth: Up to 2,500 MHz·km at 850 nm and 1300 nm for OM2 fibres
Numerical aperture: 0.200 ± 0.015 (OM2); 0.275 ± 0.015 (OM1)
Group refractive index: 1.482 at 850 nm; 1.477 at 1300 nm

Standards & Certifications

FOMFLEX is manufactured and tested to rigorous international and regional standards:

Base standard: EN 60794‑3 for outdoor optical fibre cables
Mechanical testing: DIN VDE 0298‑3 for bending and tensile performance
Flame propagation: PN‑EN 60332‑1‑2 / IEC 60332‑1‑2
Oil resistance: PN‑EN 60811‑404
UV resistance: UL 2556 / ISO 4892‑2
Ozone resistance: PN‑18D1431‑1
Local compliance: Suitable for installation under South African SANS requirements for port and mining infrastructure

These specifications confirm that FOMFLEX is not just a cable but a fully certified system designed to operate reliably in conditions that would quickly degrade ordinary cables.

Structure, Materials & Engineering Principles

The true value of FOMFLEX lies in how it is built. Every layer serves a specific purpose, and every material is selected based on clear engineering and material science principles. The design follows a simple but powerful rule: keep the optical fibres in a zero‑stress zone while placing all mechanical forces on dedicated strength members.

Layer‑by‑Layer Construction

Starting from the core and moving outward, the structure is as follows:

Optical Fibres

Each fibre is made of silica glass with a core and cladding, coated with a dual‑layer acrylate buffer. Fibres are colour‑coded according to IEC 60794: red, green, blue, white, violet, orange, grey, yellow, brown, pink, black, turquoise. This ensures easy identification during termination.

PBT Loose Tube

The fibres are housed inside a thermoplastic tube made of polybutylene terephthalate (PBT), with an inner diameter of approximately 2.6 mm and wall thickness of 0.5 mm. The tube is not tightly filled — it leaves space so fibres can move freely inside.

Thixotropic Filling Gel

Inside the loose tube, a special non‑dripping gel fills all empty space. This gel is thixotropic, meaning it stays firm when stationary but flows slightly under mechanical stress. It blocks water ingress, prevents ice formation, and isolates the fibres from radial pressure.

Central Strength Member

Running through the centre is a dielectric rod made of fibre‑reinforced plastic (FRP), 0.5 mm in diameter. It provides longitudinal rigidity and compressive strength, preventing the cable from buckling when bent. Unlike steel, FRP is non‑conductive, non‑magnetic, and has a thermal expansion coefficient very close to that of glass fibre.

Wrapping Layer

A gas‑tight polyester tape is wrapped around the tube assembly to hold components in place, add mechanical cushioning, and form a barrier against moisture and gas migration.

Inner Sheath

Over the wrapping, a thermoplastic elastomer (TPE) inner sheath is extruded, with a minimum thickness of 0.8 mm. TPE combines the elasticity of rubber with the processing advantages of plastic, offering good low‑temperature flexibility and abrasion resistance.

Aramid Reinforcement Braid

The most critical mechanical layer is a tightly woven braid of high‑modulus aramid fibres, such as Kevlar. Aramid has a tensile strength five to six times higher than steel of the same weight, with very low elongation. This layer carries almost all tensile forces, ensuring the optical core remains stress‑free.

Outer Sheath

The final layer is an extruded jacket of special synthetic thermoset rubber compound, formulated to meet DIN VDE 0207‑21. It is orange in colour, resistant to ozone, UV radiation, mineral oils, greases, and extreme temperature cycles.

Science Behind the Design

The construction follows three fundamental engineering principles:

Stress Decoupling

When a cable bends, the inner radius is compressed and the outer radius stretched. The neutral axis is the line where no compression or tension occurs. In FOMFLEX, the optical fibres lie along or near this neutral axis. The loose tube and gel allow them to shift slightly so they never experience tension or crushing. This is why bending does not cause micro‑bending loss or breakage.

Modular Load Distribution

Tensile forces are absorbed by the aramid braid; compressive forces are resisted by the FRP rod; radial pressure is buffered by the gel and TPE. This distribution ensures that no single component is overloaded, greatly extending the cable’s fatigue life.

Thermal Compatibility

The FRP rod and PBT tube have coefficients of thermal expansion close to silica glass. When temperature changes from ‑35 °C to +70 °C, all layers expand and contract at nearly the same rate, eliminating internal thermal stress that would otherwise degrade performance over time.

Environmental Barrier System

The multi‑layer structure creates a “labyrinth” against moisture, UV, and ozone. The gel blocks water along the fibre; the PBT tube resists chemical attack; the rubber sheath contains stabilizers that absorb UV and neutralize ozone, preventing polymer chain breakdown.

Competitive Advantages vs. Conventional Solutions

To fully appreciate FOMFLEX, it helps to compare it with the two most common approaches used in ports and mines: stationary optical cables and copper power/control cables.

FOMFLEX vs. Standard Fixed‑Optical Cables

Standard outdoor cables are designed for static installation. When used in moving festoon systems:

Flex life: FOMFLEX withstands more than 10 million bending cycles; standard cables often fail after 10,000–20,000 cycles.
Tensile rating: FOMFLEX supports up to 2,000 N; standard cables have little or no tensile capacity and require a separate steel messenger wire.
Installation: FOMFLEX is self‑supporting; traditional setups add weight, complexity, and maintenance points.
Dynamic loss: FOMFLEX maintains attenuation change below 0.1 dB/km even after years of movement; standard cables show increasing loss due to micro‑bending.

FOMFLEX vs. Copper‑Based Control Cables

Copper cables have been used for decades, but they have inherent limitations:

EMI immunity: Fibre‑optics are completely immune to interference from motors, variable‑frequency drives, and heavy electrical equipment — a major issue in crane cabins and control rooms.
Signal range: Fibre can transmit data reliably over 10 km or more; copper suffers voltage drop and signal distortion over longer distances.
Weight and size: FOMFLEX is typically 60 % lighter and smaller than equivalent copper systems, reducing drag and load on festoon trolleys.
Longevity: Rubber‑sheathed fibre lasts 2–3 times longer than copper, which oxidizes and fatigues faster.

Core Value Proposition

The design of FOMFLEX delivers four key benefits:

Truly dynamic‑first engineering: It treats fatigue life, torsion resistance, and dynamic attenuation as primary design criteria, not afterthoughts.
All‑in‑one functionality: Combines communication, mechanical strength, and environmental protection in a single cable.
Lower total cost of ownership: While the initial purchase price is slightly higher, the operational cost is much lower — 80 % fewer failures, 60 % less maintenance time, and fewer unplanned shutdowns.
Balanced standardization and customization: Available in 2–24 fibre counts, but can be adjusted in sheath thickness, strength member size, and fibre type to match specific travel speeds, distances, and temperature ranges.

Applications & South African Field Case Studies

South Africa is the busiest logistics and mining hub in Africa, with ports handling millions of tonnes of cargo annually and mines producing vast quantities of minerals. In these environments, machinery operates 24 hours a day, seven days a week, under conditions that are among the harshest in the world.

Typical Operating Conditions

Climate: Summer temperatures from 35 °C to 45 °C, winter nights dropping to ‑5 °C; high solar UV radiation, humidity often exceeding 90 %, and frequent coastal salt spray.
Mechanical environment: Constant acceleration/deceleration, vibration from uneven tracks, shock loads, and hundreds of back‑and‑forth movements each day.
Industrial atmosphere: Heavy dust, coal or mineral particles, hydraulic oil mist, and ozone from electrical equipment.

Case 1 — Port of Durban

The Port of Durban is the busiest container terminal in Africa, operated largely by Transnet Port Terminals. Ship‑to‑shore cranes (STS) and rubber‑tyred gantries (RTG) move continuously, transferring containers between vessels and storage yards.

The challenge: Previous installations used standard loose‑tube cables or copper control lines. These required replacement every 18–24 months. Frequent failures caused PLC timeouts, slow crane response, and occasional stoppages.

The solution: Operators installed FOMFLEX Festoon with 12 G62.5/125 fibres in festoon systems. The cable was installed with a minimum bending radius of 220 mm and operated at up to 220 m/min.

Results: After five years of continuous service, inspections showed no fibre breakage, attenuation changes of less than 0.1 dB/km, and no visible cracking or hardening of the outer jacket. The link remained stable, with control response times consistently below 10 ms, eliminating the need for frequent maintenance stops.

Case 2 — Port of Cape Town

Located on the Atlantic coast, Cape Town experiences strong winds, salt‑laden air, and high levels of UV radiation. Traditional cables often developed surface cracks after two to three years, allowing moisture to penetrate and degrade internal components.

The solution: FOMFLEX’s specially formulated rubber jacket, tested to ISO 4892‑2 standards, resists UV degradation and ozone attack. The outer sheath contains carbon black and antioxidant additives that block harmful radiation and prevent polymer chain scission.

Results: After four years of exposure, the cable remains flexible and intact. It has passed local SANS accelerated‑ageing tests, confirming an expected service life of more than 10 years in this coastal environment.

Case 3 — Richards Bay & Manganese Mines

Richards Bay is South Africa’s main export terminal for coal, iron ore, and chromium, while the MMC manganese refinery operates large‑scale handling equipment. Condra cranes, with 32‑tonne lifting capacity and 30‑metre span, travel at 200 m/min. The old cables suffered from high EMI from frequency converters and frequent damage from track irregularities.

The solution: FOMFLEX’s non‑metallic construction eliminates electromagnetic interference. The FRP‑aramid composite structure absorbs shock loads and maintains a safety margin well above the 2,000 N working load.

Economic impact: At this terminal, every hour of unplanned downtime costs approximately 15,000 ZAR. By extending service life from 2 years to over 5 years, the system paid for itself in less than 18 months, while reducing labour and spare‑part costs.

Equivalent Solution: Feichun FIBER‑FLEX / FOM‑FLEX Festoon

While TFKable FOMFLEX sets the technical benchmark, Feichun Cables offers a fully equivalent alternative — FIBER‑FLEX Festoon — designed to the same specifications and standards, with advantages for local and regional buyers.

Performance Equivalence

Same construction: PBT loose tube, thixotropic gel filling, FRP central member, TPE inner sheath, aramid braid, and rubber outer jacket.
Identical ratings: Temperature range ‑35 °C to +70 °C mobile, 2,000 N tensile, 100°/m torsion, 250 m/min speed.
Compliance: Meets EN 60794‑3, DIN VDE 0298‑3, IEC 60332, and is compatible with SANS requirements.
Optical performance: Matches attenuation and bandwidth figures for OM1, OM2, and single‑mode fibres.

Supply & Commercial Benefits

Cost: Typically 20–30 % lower in price than European‑sourced equivalents.
Lead time: Delivery in 3–4 weeks, compared to 10–16 weeks for imported stock.
Local support: Available from regional stock points in Southern Africa, reducing logistics delays.
Customization: Can adjust fibre count, sheath thickness, and reinforcement strength to match specific project parameters.

This makes Feichun’s solution a direct drop‑in replacement, ideal for operators looking to maintain reliability while optimizing capital expenditure.

Selection Guide & Installation Best Practices

Choosing and installing FOMFLEX correctly ensures maximum service life and performance.

How to Select

Fibre type: Use OM1/OM2 for short‑distance, high‑speed control; use G.652 or G.657 single‑mode for longer runs over 2 km.
Fibre count: 4–8 cores for basic control; 12–24 cores for multiple systems, redundancy, and future expansion.
Bending radius: Always maintain at least 20 × D for moving sections; avoid tight loops or sharp edges.
Tension control: Keep working tension below 1,500 N to maintain safety margin.

Installation Rules

Do not pull by the optical core; use the pulling grip designed for the strength members.
Avoid kinking, twisting, or dragging over rough surfaces.
Allow sufficient slack in festoon runs to prevent over‑tension during acceleration.
Terminate in sealed, weather‑resistant junction boxes.

Maintenance

Annual inspection: Check jacket for abrasion, cracks, or hardening.
Bi‑annual testing: Measure optical attenuation to detect early signs of degradation.
Lubricate festoon trolley wheels and guide rollers to reduce friction.

Frequently Asked Questions

Q: Can FOMFLEX be used in fixed installations only?

A: Yes, but it is designed for motion. In fixed use, it offers extra protection but is more expensive than stationary cables.

Q: Does it need a separate steel messenger wire?

A: No. The aramid braid provides sufficient tensile strength, simplifying installation and reducing weight.

Q: Can it withstand being wound on cable reels?

A: Yes, provided the minimum bending radius is observed. It is suitable for both festoon and motor‑driven reel systems.

Q: How long is the expected service life?

A: Under normal operating conditions, 8–12 years, compared to 2–4 years for standard cables.

Q: Is it compatible with standard optical connectors?

A: Yes, it can be terminated with SC, LC, ST, or FC connectors using standard fibre‑optic preparation tools.

Conclusion

FOMFLEX Festoon represents the successful integration of mechanical engineering, optical physics, and advanced polymer science. It moves beyond the limitations of both copper and stationary fibre‑optic cables by applying the principle of decoupling: separating delicate signal transmission from the forces of motion and environment.

In South Africa’s ports and mines, where equipment runs hard and downtime is costly, this technology changes the economics of automation. It delivers stable, interference‑free communication, reduces maintenance frequency, and extends the service life of critical infrastructure. It truly acts as the “nerve and ligament” of modern machinery — flexible, strong, and reliable.

For buyers and engineers, the choice is clear: if the cable must move, bend, and survive, it must be designed for that exact purpose.

Call to Action

If you are upgrading festoon systems, port cranes, stacker‑reclaimers, or mining conveyor communication links and need reliable, cost‑effective flexible optical cables, contact the Feichun Cables technical team.

Email: Li.wang@feichuncables.com