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Product Description
Heat shrinkable tubing is a two-process product: the tube is first extruded, then irradiated and expanded. The extruded tube blank decides the wall concentricity, the surface finish and the electrical performance; the expansion stage decides the shrink ratio and the final dimensional consistency. Sourcing the two stages from one partner removes the mismatch that causes most production losses.
Wall eccentricity that looks acceptable at the extruder becomes a bulge or a thin wall after expansion, and thin walls fail the dielectric test.
Response: extrusion runs through the extruder — extrusion die — cooling and setting water tank — tractor — winder sequence, with the extruder selected from the SJ series, so wall thickness and concentricity are controlled from the first stage.
The tube blank must reach a molten, high-elastic state and stay there while it is expanded; uneven heating produces one-sided wall thickness.
Response: the expansion line uses a glycerin heating box with electric heating of glycerin, bringing the tube blank to a molten and high elastic state, followed by die positioning, vacuum control and water cooling in one continuous pass.
When the tubing is heat-shrunk, its thickness increases, which in turn increases its overall dielectric withstanding voltage — which is exactly why wall consistency through expansion matters.
Response: good-quality tubing can expand to more than twice its size on this equipment, and the vacuum control part regulates the vacuum size of the mould while the water cooling part controls the amount of water in the mould to cool the expanded tubing evenly.
Heat shrink tubing ranges from thin electronic tube to heavy-wall busbar and cable protection tubing, and each size change can mean a different tube blank.
Response: the extrusion die accepts different specifications of moulds within a certain range, so one line produces products of different specifications. Drying hopper models of 25 KG, 50 KG, 75 KG and 100 KG cover the material throughput of different extruder sizes.
Tube blank must be wound without ovality or tension marks, because the wound coil is the input to the expansion line.
Response: the line is equipped with a fully automatic vacuum feeding machine and a rewinding machine with a large diameter rewinding disc, preparing the coil for the next step — electron accelerator irradiation.
The Extruder & Expander of Single-wall Heat Shrinkable Tubing is a continuous production line that covers both halves of the heat shrink tube process: extrusion of the tube blank and the expansion that gives it its shrink memory. Extrusion is a process used to create objects of a fixed cross-sectional profile by pushing material through a die of the desired cross-section — it produces excellent surface finish, allows very complex cross-sections and works materials that are brittle, because the material encounters only compressive and shear stresses.
The equipment is built for continuous or semi-continuous production, with hot or cold material, and covers the heat shrink tubing families required by industry:
Single-wall heat shrinkable tubing — the standard thin and medium wall product
Power busbar heat shrinkable tubing — heavy wall insulation for busbar systems
Electronic cable protection heat shrinkable tubing — wire harness and connector protection
Marine water pump waterproof double-wall heat shrinkable tubing — wet-environment sealing
Environmentally friendly halogen-free heat shrinkable tubing — RoHS-oriented compounding
Medical equipment heat shrinkable tubing — tight-tolerance small bore tube
Heat shrinkable tube for high speed rail — rail and transit applications
Electronic thin tube for computers, air conditioners and refrigerators — thin-wall fine tube
Packaging heat shrinkable tube — packaging and protection
Memory pipe production lines — tubing with retained memory effect
Materials handled across the program include PE, EVA, PET, PVC, PEEK and FEP. The neighboring line for dual-wall products is described on Chenxing's pipe extrusion line solution and other type pipe extrusion line solution pages.
The extrusion stage turns resin into a dimensionally stable tube blank:
Extruder — models available: SJ-45, SJ-55, SJ-65, SJ-75 and SJ-90 extruder
Extrusion die — within a certain range, different specifications of moulds can be replaced to produce products of different specifications
Cooling and setting water tank — submerged or vacuum type
Tractor — roller type or crawler type
Winder / rewinding machine — large diameter rewinding disc, preparing the coil for the next step (preparation for electron accelerator irradiation)
The extrusion line is equipped with a fully automatic vacuum feeding machine and a drying hopper (models 25 KG, 50 KG, 75 KG, 100 KG).
The SJ-45, SJ-55, SJ-65, SJ-75 and SJ-90 extruders cover the range from thin electronic tubing to heavy-wall busbar tubing. Each extruder is matched with its drying hopper size and downstream tank type, so the line is configured to the product rather than to a single fixed specification.
The heat shrinkable tube extrusion die accepts interchangeable moulds within a certain range, so different product specifications are produced on the same line by changing the mould rather than the machine.
| Tank type | Construction | Main application |
|---|---|---|
| Submerged cooling water tank | Submerged cooling | Extrusion cooling and shaping of small-sized heat shrinkable tubes |
| Vacuum cooling water tank | Vacuum cooling | Extrusion cooling and shaping of large-sized heat shrinkable tubes |
| Tractor type | Construction | Main application |
|---|---|---|
| Pair of roller traction machine | Composed of 2 pairs of rubber rollers | Extrusion traction of small-sized heat shrinkable tubes |
| Crawler tractor | Composed of 2 rubber belts | Extrusion traction of large-sized heat shrinkable tubes |
The expansion stage gives the tube blank its shrink memory, in a continuous sequence:
Unwinding stand — tube blank feeding — glycerin heating box — die positioning — vacuum control — water cooling — traction output
Pneumatic, adjustable up and down, with the unwinding disc rotating freely on it so the tube blank pays off without tension spikes.
The transmission part is driven by the motor, and the rubber roller feeds the tube blank into the glycerin box at a controlled rate.
Electric heating of glycerin heats the tube blank until it reaches a molten and high elastic state — the condition required for uniform expansion.
The transmission part is driven by the motor to realize the continuous and uniform conveying of the tube blank in the glycerin box, so every section of tube spends the same time at temperature.
The mould positioning part is used to install the expansion mould; the vacuum control part controls the vacuum size of the mould, which sets the expanded diameter.
The water cooling part controls the amount of water in the mould and cools the expanded heat shrinkable tube, locking the expanded dimension before the tube leaves the mould.
The motor drives the rubber roller to pull the expanded heat shrinkable tube for output, delivering a dimensionally stable, memory-retaining product.
The tubing produced on this equipment is used wherever electrical insulation must shrink to fit and stay tight:
Wire harness and connector protection — covering splices and terminals
Busbar insulation — power distribution insulation in switchgear and cabinets
Cable joint protection — moisture and mechanical protection in the field
Marine and pump sealing — waterproof double-wall heat shrinkable tubing
Medical devices — tight-tolerance small bore tube
High speed rail and transit — rail-grade insulation tubing
Home appliance thin tube — computers, air conditioners and refrigerators
Packaging — protective and bundling shrink tube
Related equipment programs include the profile extrusion line and profile extrusion line solution for profiles, the board sheet extrusion line for sheet, the plastic pelletizing line for in-house compounding and the plastic recycling line solution for reclaiming production scrap.
Zhangjiagang Chenxing Machinery Co., Ltd. is a plastic machinery manufacturer with more than 20 years of experience, supplying both-screw and single-screw extruders, pipe and profile extrusion lines, sheet lines, pelletizing lines, recycling lines and auxiliary machines such as crushers, mixers and pipe belling machines. Machines have been delivered to markets including Egypt, Thailand, Malaysia, India, Russia, Turkey, Zambia, Algeria and Indonesia, and the same engineering team supports heat shrink tubing projects from the extruder through the expansion stage.
Chenxing also builds the flexible-hose, pipe and small-bore tube family: see the PVC fiber reinforced soft pipe extrusion line, the HDPE pipe production line, the PPR pipe extrusion line solution, the ABS pipe production line, the corrugated pipe extrusion line solution and the laboratory-scale SJ 25/25 mini single screw extruder for material trials. Company background is on About Us; explore the full solutions catalogue too.
The single-wall line produces one-layer heat shrink tubing for insulation and protection. The dual-wall line adds an inner adhesive layer, typically for waterproof sealing such as marine pumps and cable joints. Chenxing supplies both configurations and helps you choose based on the application and the wall structure required.
Extruder models available are SJ-45, SJ-55, SJ-65, SJ-75 and SJ-90. The correct size depends on the tube diameter range, wall thickness and required output — send us your product list and we will match the extruder, die, cooling tank and tractor to it.
Yes. The extrusion die accepts different moulds within a certain range, so different product specifications are produced by changing the mould. On the expansion side, the mould positioning part is designed to install the expansion mould and the vacuum control part sets the expanded size, so size changes are handled without rebuilding the line.
The submerged cooling water tank is mainly used for extrusion cooling and shaping of small-sized heat shrinkable tubes. The vacuum cooling water tank is mainly used for extrusion cooling and shaping of large-sized heat shrinkable tubes.
The pair of roller traction machine (composed of 2 pairs of rubber rollers) is mainly used for extrusion traction of small-sized heat shrinkable tubes, while the crawler tractor (composed of 2 rubber belts) is mainly used for extrusion traction of large-sized heat shrinkable tubes.
Yes. Our engineers will guide the machine installation and train your workers on extrusion settings, expansion temperature control and routine maintenance.
The rewinding machine uses a large diameter rewinding disc to prepare the coil for the next step — electron accelerator irradiation. We help customers plan the coil format and handling so the coil transfers cleanly to their irradiation service provider.
We have an experienced R&D team that ensures the feasibility of the product before production, with quality inspectors checking raw materials, patrolling production and re-inspecting before delivery. Payment is by T/T, L/C or Western Union, confirmed in the formal quotation. More answers are on our FAQ list.
Tell Chenxing which tubing you produce — wall structure, diameter range, shrink ratio target and material (PE, EVA, PET, PVC, PEEK or FEP) — and the engineering team will confirm the extruder model, die and mould set, cooling tank type, tractor type and the expansion line configuration in a written quotation.
Nicole — Email: ceo@cxsljx.com | Tel WeChat WhatsApp: +86 159 5118 7228
Send your tubing specification and destination port, and we will reply within 24 hours. For machine news and technical documents, see Company News and Downloads. If you are still benchmarking the extruder and expander configuration, view more machine details and send Nicole the differences against your own tubing specification.
