Tubular Stranding Systems

-- Steady & Reliable Manufacturer --

Product Introduction

Tubular stranding systems represent one of the most reliable and time-tested technologies in the wire and cable manufacturing industry. Designed to twist multiple conductors, filaments, or wires into a compact, helical assembly, these machines form the backbone of modern cable production lines worldwide. Whether you are producing power cables, telecommunication wires, armored cables, or specialty industrial conductors, a well-engineered tubular strander delivers the consistent lay length, tight dimensional tolerances, and structural integrity that today's demanding applications require.

Unlike planetary or rigid stranders, tubular stranding machines feed the wire from fixed-axis bobbins housed within a rotating tube — the core mechanical element that gives these machines their name. As the outer tube spins at high speed, the wires unwind from the bobbins and converge at the stranding point, forming a helical lay pattern that is both mechanically stable and electrically efficient. This design eliminates the need for the bobbins themselves to rotate, which greatly reduces centrifugal stress and allows the machine to run at significantly higher production speeds than competing technologies.

Our tubular stranding systems are engineered to accommodate a wide range of conductor sizes, from fine wire bunching applications all the way up to heavy-gauge power cable stranding. Modular frame designs allow the machine configuration to be adapted quickly for different bobbin counts and lay lengths, making it straightforward to transition between product runs without prolonged downtime. Precision-machined closing dies, adjustable tension control, and servo-driven capstan units work in concert to ensure each finished cable meets international quality standards including IEC, ASTM, and BS specifications.

Built with operator safety and long-term reliability in mind, our systems incorporate heavy-duty steel frames, sealed bearings, and interlocked safety guards that comply with CE and OSHA requirements. An intuitive HMI (Human–Machine Interface) panel allows operators to monitor real-time machine parameters — including rpm, lay length, line speed, and tension values — and make on-the-fly adjustments without interrupting production. With decades of field experience behind our engineering team, each machine that leaves our facility has been meticulously assembled, tested, and calibrated to deliver consistent, high-quality output from day one.

Whether you are setting up a greenfield cable plant or upgrading an existing stranding line, our tubular stranding systems offer a compelling combination of throughput, versatility, and total cost of ownership that is difficult to match with alternative stranding technologies.

Technical Specifications

The table below summarizes the standard performance and dimensional parameters of our tubular stranding system range. Custom configurations are available upon request for non-standard conductor diameters, bobbin counts, or lay length requirements.

Parameter	Standard Range / Value
Number of Bobbins	7 / 12 / 19 / 24 / 37 (configurable)
Bobbin Flange Diameter	250 mm – 800 mm
Max. Wire Diameter (Single)	0.05 mm – 12.0 mm
Stranding Tube Rotation Speed	Up to 1,800 rpm (model-dependent)
Line Speed	5 – 200 m/min
Lay Length Range	8 mm – 500 mm (stepless adjustment)
Stranding Direction	Left-hand (S) / Right-hand (Z) — switchable
Closing Die Diameter	Customized to conductor OD
Capstan Drive	AC servo motor with encoder feedback
Take-up Reel Diameter	400 mm – 1,600 mm
Main Drive Power	7.5 kW – 90 kW (model-dependent)
Tension Control	Dancer arm + magnetic powder brake (per bobbin)
Frame Material	Heavy-duty cast iron / welded steel
Control System	PLC + 10-inch touch-screen HMI
Supply Voltage	380V / 415V / 480V, 3-phase (customizable)
Operating Temperature	0 °C – 45 °C
Machine Dimensions (L × W × H)	4.5 m – 18 m × 1.2 m – 2.8 m × 1.6 m – 2.4 m
Net Weight	2,500 kg – 28,000 kg (model-dependent)
Certification	CE, ISO 9001:2015
Conductor Materials Supported	Copper, Aluminum, Steel, CCA, ACSR, Alloy

All specifications are subject to confirmation based on final product requirements. Our engineering team can provide detailed drawings, 3D models, and layout plans prior to order confirmation.

Application

Tubular stranding systems are deployed across a remarkably broad spectrum of cable manufacturing scenarios, making them one of the most versatile machine categories in the industry. Below is an overview of the primary fields and specific product types where these systems deliver exceptional results.

Power Cable Conductors: The most common application, tubular stranders produce multi-wire conductors for low-, medium-, and high-voltage power cables. Stranded copper or aluminum conductors improve flexibility and current-carrying efficiency compared to solid conductors, making them ideal for grid-level distribution and building wiring.
Overhead Transmission Lines: ACSR (Aluminum Conductor Steel Reinforced) and AAC (All-Aluminum Conductor) cables used in overhead power lines require precise concentric stranding with tight lay-length control — a task tubular stranders handle with ease at production speeds competitive enough to meet utility-scale demand.
Telecommunications Cables: Twisted-pair and multipair telephone cables, data cables (Cat.5e / Cat.6 / Cat.6A), and coaxial cable cores all rely on tubular stranding or bunching to achieve the necessary electrical balance and crosstalk attenuation required by telecommunications standards.
Armored and Instrumentation Cables: Steel wire armoring (SWA) and steel tape armoring (STA) applied over cable cores use tubular stranders to lay armor wires uniformly, providing mechanical protection for cables routed through conduits, buried underground, or installed offshore.
Flexible and Control Cables: Fine-wire bunching applications for flexible cords, elevator cables, robotics trailing cables, and industrial control cables demand precise pitch control and consistent twist per unit length — requirements met by variable-speed tubular stranding configurations.
Automotive and Aerospace Wiring: Lightweight twisted-pair and shielded cables for vehicle CAN bus systems, aircraft avionics harnesses, and EV battery wiring harnesses are produced using high-speed tubular bunching and stranding lines specifically tuned for thin-gauge, high-purity copper or silver-plated wire.
Submarine and Offshore Cables: Subsea power and fiber-optic cable assemblies require multi-layer concentric stranding of both conductors and tensile strength members. Tubular stranders equipped with high-capacity take-up reels handle the substantial weight and stiffness of these large-diameter assemblies.
Specialty Wire Products: Medical device cables, mining cables with flame-retardant jackets, railway signaling cables, and nuclear plant instrumentation cables all have unique stranding specifications that tubular systems can accommodate through customized die sets and tension profiles.

Thanks to the ease with which bobbin count, tube speed, and take-up parameters can be adjusted, a single tubular stranding line can often serve multiple application categories within the same production facility — maximizing capital equipment utilization and reducing the need for dedicated single-purpose machines.

Advantages

Choosing a tubular stranding system over alternative stranding technologies is a decision that pays dividends throughout the entire lifecycle of your cable manufacturing operation. Here are the key advantages that set these machines apart.

High Production Speed: Because the bobbins remain stationary while only the outer tube rotates, centrifugal forces on the wire are dramatically reduced. This allows the machine to achieve rotation speeds of up to 1,800 rpm — far exceeding what is safely achievable with rigid frame or planetary stranders of comparable bobbin count. Higher rpm translates directly into greater line speed and more meters of finished cable per shift.
Consistent Lay Length Accuracy: Servo-driven capstan and take-up units combined with closed-loop feedback control maintain the programmed lay length to within ±1% tolerance across the full production run. This level of consistency is critical for cables where electrical performance — such as characteristic impedance in data cables — is directly dependent on twist pitch.
Low Wire Tension Variation: Individual dancer arms and magnetic powder brakes on each bobbin position ensure that every wire enters the stranding point under equal, controlled tension. Uniform tension prevents conductor deformation, reduces scrap rates, and produces a geometrically tight, round stranded core with excellent surface finish.
Bidirectional Stranding: The ability to switch between left-hand (S) and right-hand (Z) lay directions without major mechanical reconfiguration is a practical advantage in multi-layer cable designs and when fulfilling contracts with opposing helical direction requirements.
Wide Product Range from a Single Machine: Modular closing die holders, adjustable bobbin positions, and programmable speed ratios allow a single tubular strander to handle product diameters across a broad range without the need for a completely separate machine investment.
Reduced Maintenance Downtime: Fixed-axis bobbins experience far less mechanical stress than bobbin cradles in rigid frame stranders. Sealed, self-lubricating bearings in the tube assembly extend service intervals significantly, and quick-change bobbin holders reduce reel changeover time to a fraction of what older machine designs require.
Energy Efficiency: Optimized main drive designs, regenerative braking on the take-up axis, and variable frequency drives (VFDs) on all major motors reduce total energy consumption by up to 20% compared to older fixed-speed machine designs — a meaningful saving when machines run multiple shifts daily.
Operator-Friendly Control: A color touchscreen HMI presents all critical process parameters on a single screen. Recipe storage allows operators to recall exact settings for repeat orders in seconds, eliminating the risk of human error during setup and reducing trial scrap at the start of each production run.
Scalable and Future-Ready: Our machines are designed with expansion in mind. Ethernet connectivity, OPC-UA data interfaces, and compatibility with MES (Manufacturing Execution System) platforms allow tubular stranding lines to be integrated into smart factory environments, supporting real-time process monitoring, predictive maintenance, and traceability requirements.

Material and Structure

The performance of a tubular stranding system is inseparable from the quality of its core mechanical components and the engineering discipline applied to their selection and integration. Every major assembly in our machines is designed for longevity, precision, and ease of maintenance.

Machine Frame: The base frame is fabricated from heavy-gauge structural steel sections, fully welded and then stress-relieved before machining. This ensures dimensional stability over years of high-speed operation and prevents the vibration-induced resonance that can shorten bearing life and compromise stranding geometry. All critical machined surfaces are precision-ground on CNC machining centers to tolerances of ±0.01 mm.

Stranding Tube Assembly: The rotating tube — the defining structural element — is manufactured from high-tensile alloy steel and dynamically balanced to G2.5 grade or better in accordance with ISO 21940. Precise balancing at operating speed is essential to prevent vibration at high rpm, which would introduce unwanted tension fluctuations in the wires. The tube is supported at both ends by large-diameter, deep-groove ball bearings or tapered roller bearings, selected according to the radial and axial load profile of each machine size.

Bobbin Cradle and Holders: Each bobbin position features a hardened steel shaft, precision-bored cradle arms, and an easily releasable locking collar that secures the bobbin flange without the need for tools. The cradle geometry is machined to keep the wire tangent point aligned with the stranding axis, minimizing transverse wire bending as it exits the bobbin.

Wire Guide and Closing Die System: From each bobbin, the wire passes through polymer-lined guide tubes or ceramic eyelet guides before converging at a tungsten carbide or hardened steel closing die. Carbide dies offer superior wear resistance when stranding hard-drawn copper or steel wires, while polished hardened steel dies are suitable for soft-drawn copper and aluminum. Die holders are designed for rapid exchange — an important production-efficiency feature when the machine serves multiple product families.

Capstan and Take-up Unit: The capstan drum is driven by an AC servo motor through a precision helical gearbox, providing smooth, backlash-free torque delivery. The take-up unit uses a traverse mechanism with programmable pitch to ensure even, cross-wound coil formation on the shipping reel. The traverse pitch is automatically adjusted by the PLC as the reel diameter grows, maintaining a consistent winding angle throughout the fill cycle.

Tension Control Components: Each bobbin position is equipped with a spring-loaded dancer arm that provides passive tension buffering, supplemented by a magnetic powder brake whose braking torque is continuously regulated by the PLC based on the dancer arm position signal. This dual-mode approach handles both slow, quasi-static tension drift and fast transient tension spikes caused by any irregularity in the incoming wire.

Lubrication System: Main bearings in the tube assembly are connected to a centralized automatic grease lubrication circuit that delivers measured quantities of high-temperature grease at timed intervals, ensuring consistent lubrication film without the risk of over-greasing. Secondary bearings throughout the machine use sealed, pre-greased units that typically require no field lubrication for the life of the bearing.

Safety Guards and Enclosures: Interlocked polycarbonate and steel mesh guards enclose all rotating tube sections. Emergency stops are located at both the operator station and along the machine perimeter, and a light curtain across the infeed zone prevents inadvertent access during operation. All safety interlocks are dual-channel, meeting PLe / Cat. 4 requirements under ISO 13849.

Installation Tips

Proper installation is one of the most critical factors determining the long-term performance and accuracy of your tubular stranding system. Cutting corners during installation invariably leads to premature bearing wear, stranding geometry problems, and extended commissioning time. The guidance below reflects best practices developed through hundreds of machine installations across different facility types and climate conditions.

Foundation Requirements: Tubular stranders generate significant dynamic forces during high-speed operation, particularly at tube rotation speeds above 800 rpm. We strongly recommend a reinforced concrete inertia block or isolated machine foundation capable of absorbing these forces without transmitting vibration to adjacent equipment. Minimum foundation thickness is 300 mm for smaller machines and 600 mm for machines with tube OD above 400 mm. Foundation anchor bolts should be grouted in epoxy rather than standard cement for maximum pull-out strength.
Leveling and Alignment: Before final grouting of anchor bolts, the machine frame must be leveled in both longitudinal and transverse directions to within 0.05 mm/m using a precision spirit level. The stranding tube axis must be co-axial with the capstan and take-up spindle axes. Any angular misalignment greater than 0.1° will cause cyclic bending stress in the stranded conductor and visible "corkscrew" deformation at the die outlet.
Electrical Supply: Confirm that the supply voltage and frequency match the machine nameplate before connecting. Provide a dedicated isolation transformer or line filter if the facility power supply exhibits voltage spikes or harmonic distortion above 5% THD (Total Harmonic Distortion), as these can interfere with servo drive performance. Earth bonding must be completed to the machine frame and all VFD panels before powering up for the first time.
Wire Threading Procedure: Thread wires through guide tubes while the tube is stationary. Start from the innermost bobbin positions and work outward. Avoid sharp bends in the wire guide path; the minimum bend radius for each wire size is specified in the machine manual. After threading, hand-rotate the tube one full revolution to confirm there is no wire crossing or fouling before energizing the main drive.
Initial Run-In: For the first 8 hours of operation on a new machine, run at no more than 50% of maximum tube speed. This allows the main bearings to seat properly and permits any minor alignment imperfections to self-correct under load. Monitor bearing temperature and vibration levels during this run-in period. Bearing housing temperature should stabilize below 70°C; any sustained reading above 80°C requires investigation before continuing.
Die Selection and Setting: Select closing die inner diameter based on the theoretical finished conductor outer diameter plus a compression allowance of 2–4% depending on conductor material and construction. Too large a die produces a loose, non-circular strand; too small a die over-compresses the conductor and can cause surface wire breakage. Always verify die condition before use — a worn or chipped die will immediately degrade surface finish and dimensional accuracy.
Tension Pre-set: Before the first production run, set individual bobbin tensions to the values specified in the product recipe or engineering data sheet. A simple check is to pull each wire by hand at the infeed point — all wires should feel the same. Unequal tension at this stage will produce an unbalanced strand with some wires in compression and others in tension, which is a common root cause of early conductor fatigue in service.
Grounding and EMC: Ensure all VFD motor cables are run in separate conduit from signal cables. Use shielded cables for all encoder, HMI, and PLC I/O connections, with shields terminated at one end only (the panel end). Poor EMC practice during installation is the single most common cause of intermittent control system faults that are difficult to diagnose in the field.

Our after-sales team provides on-site installation supervision and commissioning assistance. We strongly recommend engaging our engineers or a certified local representative for the initial machine commissioning, particularly for facilities new to tubular stranding technology.

Comparison with Other Stranding Technologies

Selecting the right stranding technology for your cable production line requires a clear understanding of how different machine types compare across key performance dimensions. The table below positions tubular stranding systems against the two most common competing technologies: rigid (planetary) stranders and skip stranders (bow stranders).

Criterion	Tubular Strander	Rigid (Planetary) Strander	Skip / Bow Strander
Max. Rotation Speed	Up to 1,800 rpm	200–400 rpm	600–1,200 rpm
Bobbin Capacity	7 – 37 bobbins	7 – 91 bobbins	1 – 6 bobbins
Wire Size Range	0.05 mm – 12 mm	0.3 mm – 25 mm	0.1 mm – 8 mm
Lay Length Accuracy	±1% (servo-controlled)	±1.5–2%	±1–1.5%
Changeover Time	Low (recipe recall)	High (mechanical gearing)	Medium
Wire Tension Control	Per-bobbin dancer + brake	Per-bobbin brake (no dancer)	Bow spring tension
Centrifugal Wire Stress	Low (bobbin stationary)	Very High (bobbin rotates)	Medium
Floor Space Requirement	Moderate	Large	Small
Investment Cost	Medium–High	High	Low–Medium
Operating Cost (Energy)	Low–Medium (VFD, regen)	High	Low
Suitable for Fine Wire	Yes (down to 0.05 mm)	Limited	Yes
Suitable for Heavy Gauge	Yes (up to 12 mm/wire)	Yes (best for large cross-sections)	Limited
Maintenance Complexity	Low–Medium	High (rotating cradles)	Low
Smart Factory Integration	Full (OPC-UA, Ethernet)	Partial	Basic

Summary: Tubular stranding systems occupy a strong middle ground — they outperform rigid stranders on speed, wire stress, and operating cost, while offering a far broader wire diameter range and bobbin count than skip stranders. For medium-to-high volume production facilities requiring flexibility across multiple product types, a tubular system typically delivers the best balance of throughput, quality, and total cost of ownership. Rigid stranders remain the preferred choice only for the very largest cross-section conductors (above 1,000 mm²) where their higher torque capacity is essential. Skip stranders are best suited to simple, single-pair or thin-wire applications where capital investment must be minimized.

Frequently Asked Questions

Q: What is the typical production speed of a tubular stranding system?
A: Production speed depends on the conductor specification, lay length, and machine model. In practice, line speeds between 30 m/min and 150 m/min are common for standard power cable conductors, with some fine-wire bunching applications achieving up to 200 m/min. Tube rotation speeds of up to 1,800 rpm are achievable on high-speed models, and this — combined with the programmed lay length — determines the net linear output rate. Our engineering team can calculate the expected throughput for your specific product mix during the quotation stage.

Q: How do I choose the right number of bobbins for my application?
A: Bobbin count is driven by the stranded conductor construction specified in your product standard — for example, IEC 60228 Class 2 round compact stranded conductors require specific numbers of wires per layer. Common constructions include 7-wire, 19-wire, and 37-wire configurations. If you anticipate producing a wide range of conductor sizes, a machine with a higher maximum bobbin count (e.g., 37 positions) gives you the most flexibility, as you can always leave positions empty for smaller constructions. We can map your full product range to a recommended machine configuration upon request.

Q: Can the same machine handle both copper and aluminum wire?
A: Yes. Tubular stranding systems are fundamentally material-agnostic — the key changes between copper and aluminum processing are the tension settings and the closing die specification. Aluminum wire is softer and more prone to surface marking, so tension values should be set lower and die surface finish requirements are more stringent. We supply machines with application-specific die sets and can advise on optimal tension profiles for both materials. Steel wire stranding (for armor layers) is also supported with appropriate heavy-duty guide and die components.

Q: What foundation is required for installation?
A: We recommend a reinforced concrete inertia block with a minimum thickness of 300 mm for smaller machines and 600 mm for larger models. The foundation should be isolated from adjacent equipment pads to prevent vibration transmission. Anchor bolt positions and loading data are provided in our foundation drawing, which is included in the documentation package supplied with every machine order. For facilities with floating concrete floors or steel mezzanine structures, our engineering team can design custom isolation mounting solutions.

Q: How long does it take to change over from one product to another?
A: With the recipe management system in the PLC, speed and lay length parameters can be recalled in under a minute. Closing die exchange, if required, typically takes 10–20 minutes. Full bobbin reel changes depend on how many positions need to be re-loaded but are generally completed within 30–60 minutes by a trained two-person crew. Overall, product changeover on a tubular strander is substantially faster than on a rigid planetary strander, which may require mechanical gear changes that can take several hours.

Q: What maintenance schedule should I follow?
A: Our standard recommended maintenance schedule includes a daily inspection of wire guides, dancer arm freedom, and safety guard integrity; weekly checks of bearing temperature and lubrication levels; monthly inspection of closing dies for wear, brush contacts (if AC slip-ring drive is used), and capstan belt tension; and an annual full inspection of main tube bearings, gearbox oil, and all safety interlock circuits. The centralized auto-lubrication system reduces the daily lubrication burden significantly. A detailed maintenance schedule with part numbers for all wear items is included in the machine manual.

Q: Is remote monitoring or Industry 4.0 connectivity available?
A: Yes. Our current generation of tubular stranding systems is equipped with an OPC-UA server built into the PLC, enabling real-time data streaming to plant-level MES or SCADA systems. Key parameters — including tube rpm, line speed, lay length, tension values per bobbin, and production meter count — are available as live data tags. Optional modules include an edge computing gateway for predictive maintenance analytics, and remote access via VPN for our service team to perform diagnostics without requiring an on-site visit. Detailed integration specifications are available for your IT team upon request.

Q: What after-sales support do you provide?
A: We provide comprehensive after-sales support including on-site installation and commissioning assistance, operator and maintenance training (on-site or at our factory), a 12-month warranty on all major components, access to a spare parts inventory with fast international shipping, and a dedicated technical support hotline staffed by experienced engineers. Long-term service contracts with scheduled preventive maintenance visits are also available. Our goal is to ensure that your machine operates at peak performance throughout its entire service life, and our global network of service partners means support is available in most major manufacturing regions.