Introduction
Zhoushan City Jinjiu Machinery Manufacture Co., Ltd. (舟山市金久机械制造有限公司) is a privately held Chinese manufacturer of screws, barrels, and related wear components for plastics, rubber, chemical-fibre, and other processing machinery. The company is located in Jintang Town, Dinghai District, Zhoushan, Zhejiang Province, an industrial area widely associated with the manufacture of plastic-processing screw and barrel assemblies.
Jinjiu’s principal products are replacement and custom-engineered screw–barrel systems for injection-moulding machines and extrusion equipment. Its stated production range covers injection machines from approximately 30 to 20,000 g, single-screw extruders with screw diameters of about 15–300 mm, parallel twin-screw extruders of approximately 30–200 mm, and conical twin-screw extruders in several diameter configurations. The company also supplies components for rubber machinery, chemical-fibre machinery, and petroleum equipment.
The business occupies a specialised position in the plastics-machinery supply chain. Rather than producing complete injection-moulding or extrusion lines, it manufactures the core rotating and conveying components that determine material transport, melting, mixing, pressure generation, throughput, and wear resistance. Its activities therefore connect metallurgical processing, precision machining, equipment maintenance, and polymer-processing technology.
History and Development
Public company materials identify Jinjiu as an established manufacturer based in Zhoushan’s Jintang machinery cluster. A company profile published through LinkedIn gives 1998 as the founding year, placing its development within the expansion of China’s plastics-processing machinery and component-manufacturing industries.
Key development milestones include:
- Establishment in the late 1990s: The company developed as a specialist producer of screws and barrels for domestic and export-oriented machinery markets.
- Expansion of product coverage: Its manufacturing scope broadened from conventional injection-moulding components to single-screw, parallel twin-screw, and conical twin-screw extrusion systems, together with components for rubber and chemical-fibre machinery.
- Development of specialised materials and surface treatments: In addition to 38CrMoAlA steel, the company describes production using GH113 nickel-based alloy and the application of welded alloy layers for selected high-wear or high-temperature conditions.
- Addition of engineering services: Jinjiu states that it undertakes component measurement, design, repair, equipment modification, and custom processing alongside standard product manufacture.
These developments reflect the broader evolution of the plastics-equipment component sector, in which customers increasingly require replacement parts configured for particular polymers, fillers, operating temperatures, machine geometries, and production conditions.
Business Operations and Segments
Jinjiu’s operations centre on the manufacture and servicing of screw and barrel assemblies. Its principal business activities can be grouped into four areas:
- Injection-moulding components: Screw and barrel systems for domestic and imported injection-moulding machines ranging from small- and medium-scale equipment to machines with nominal shot capacities of approximately 20,000 g.
- Extrusion components: Screw and barrel assemblies for single-screw, parallel twin-screw, and conical twin-screw extruders across a broad diameter range.
- Specialised industrial machinery components: Components for rubber machinery, chemical-fibre equipment, and petroleum-related machinery.
- Engineering and aftermarket services: Measurement of existing components, design assistance, repair, refurbishment, equipment modification, and processing based on customer drawings or samples.
The company also describes supplying machine manufacturers, universities, and research institutions. This indicates a business model that combines original-equipment support with replacement, maintenance, and research-oriented orders.
Products and Technologies
Screw and barrel assemblies
Screw and barrel systems are central to the operation of injection-moulding and extrusion machinery. The screw conveys polymer pellets, applies shear and heat, melts or homogenises the material, and generates the pressure required for injection or continuous extrusion. The barrel provides the heated and wear-resistant cylindrical surface within which these processes occur.
Jinjiu’s stated product portfolio includes:
- Injection-moulding screws and barrels
- Single-screw extruder components
- Parallel twin-screw components
- Conical twin-screw components
- Rubber-processing screws and barrels
- Chemical-fibre machinery screws and barrels
- High-temperature screws and barrels
- Bimetallic or alloy-surfaced components
- Tie bars, guide components, and related machine parts
Dimensional range
The company reports the following approximate dimensional capabilities:
| Equipment category | Stated range or configuration |
|---|---|
| Injection-moulding machines | Approximately 30–20,000 g shot-capacity range |
| Single-screw extruders | Approximately 15–300 mm screw diameter |
| Parallel twin-screw extruders | Approximately 30–200 mm screw diameter |
| Conical twin-screw extruders | Configurations including approximately 35/70 to 92/188 mm |
The applicable dimensions, screw geometry, flight design, compression ratio, metering section, mixing elements, and barrel configuration depend on the machine model and the processed material.
Materials and surface engineering
Jinjiu identifies 38CrMoAlA as a principal base material. This nitriding steel is commonly used for plastic-processing screws and barrels because it combines suitable strength, machinability, and capacity for surface hardening. The company describes a manufacturing sequence involving heat treatment, stabilisation, nitriding, precision grinding, and polishing.
For more demanding service conditions, the company states that it produces components from GH113 nickel-based alloy and can apply welded alloy layers to create bimetallic surfaces. Such approaches are relevant where equipment processes glass-fibre-filled, mineral-filled, flame-retardant, corrosive, or otherwise abrasive compounds. Performance depends on the alloy formulation, layer integrity, hardness profile, screw design, operating temperature, and processing parameters.
Customisation and repair
Because screw and barrel wear is strongly influenced by resin formulation and operating conditions, replacement parts are often designed to match an existing machine rather than selected solely by nominal diameter. Jinjiu states that it can conduct on-site measurement, design components, repair equipment, and modify extrusion systems. These services can reduce the need for complete machine replacement and support the continued operation of ageing equipment.
Applications and End Markets
The company’s components serve processing operations in several plastics and related-material sectors:
- Injection moulding of technical parts, consumer products, packaging items, and industrial components
- Compounding and masterbatch production using twin-screw extrusion
- Profile, pipe, sheet, film, and other continuous extrusion processes
- Processing of filled and reinforced polymers
- Rubber compounding and shaping
- Synthetic-fibre production
- Research and pilot-scale polymer processing
- Petroleum and other industrial machinery applications
The range of applications is consistent with the role of screw and barrel manufacturers as enabling suppliers. Their components are used across multiple polymer families, including commodity thermoplastics, engineering plastics, elastomeric compounds, and filled formulations, although the appropriate metallurgy and geometry vary substantially by application.
Global Presence and Market Position
Jinjiu is headquartered in Zhoushan, Zhejiang, and serves both Chinese and export-oriented machinery markets. Its company profile describes products for domestic and overseas use, while its stated customer base includes machinery manufacturers, educational institutions, and research organisations.
The company’s market position is best understood as that of a specialised component manufacturer within the larger plastics-machinery ecosystem. It competes through:
- Broad compatibility with domestic and imported machines
- Coverage of injection and extrusion applications
- Custom manufacture based on drawings, measurements, or samples
- Availability of repair and modification services
- Material options intended for standard, high-temperature, abrasive, or corrosive processing conditions
Zhoushan’s concentration of screw and barrel manufacturers creates access to machining, heat treatment, nitriding, alloy processing, and related subcontracting capabilities. At the same time, the sector is competitive and sensitive to polymer demand, machinery investment cycles, steel and alloy prices, export logistics, and customers’ requirements for predictable service life.
Research and Development
Jinjiu’s development work is primarily applied and production-oriented. Its technical activities include adapting screw and barrel designs to specific machine models, improving wear resistance, selecting materials for demanding polymers, and modifying extrusion equipment to meet processing requirements.
The principal technical variables in this field include:
- Screw diameter, length-to-diameter ratio, and flight geometry
- Compression and metering-section design
- Mixing and dispersive elements for twin-screw systems
- Steel grade and heat-treatment condition
- Nitrided or welded-alloy surface hardness
- Compatibility with abrasive fillers and corrosive additives
- Dimensional tolerances and surface finish
- Alignment between screw, barrel, gearbox, and machine frame
Such development is closely connected to industry trends including higher filler loading, recycled-polymer processing, greater use of engineering plastics, lower energy consumption, and demand for longer maintenance intervals.
Sustainability and Environmental Considerations
Jinjiu’s products can contribute indirectly to resource efficiency by extending the operating life of injection-moulding and extrusion equipment. Replacement screws, barrels, and repair services may allow processors to restore machine performance without replacing an entire production line.
The environmental profile of these products also depends on manufacturing and operating factors. Relevant considerations include:
- Energy consumption during steel production, machining, heat treatment, and nitriding
- Material use and recoverability of worn steel components
- Environmental controls for nitriding, alloy welding, grinding, and polishing
- Service life under recycled or highly filled polymer formulations
- Energy efficiency resulting from proper screw design and stable processing
- Reduction of scrap caused by inconsistent melting, mixing, or pressure generation
Longer component life can reduce replacement frequency, but the benefits depend on actual durability, maintenance practices, and the environmental performance of the manufacturing processes used.
Quality Management and Certifications
Company information states that Jinjiu obtained ISO 9001:2000 international quality-system certification and describes manufacturing according to applicable standards. Its reported production process includes heat treatment, stabilisation, nitriding, grinding, and polishing, all of which are important to dimensional accuracy and service performance in screw and barrel assemblies.
Quality control for these products generally involves verification of:
- Chemical composition and material certificates
- Heat-treatment and nitriding condition
- Surface hardness and case depth
- Screw and barrel dimensional tolerances
- Concentricity, straightness, and alignment
- Surface finish and polishing quality
- Welded-alloy bonding and integrity where bimetallic construction is used
- Fit with the customer’s machine and processing specification
Certification statements and technical specifications should be assessed against the particular product, production date, and customer requirements.
Innovations and Future Outlook
Jinjiu’s future development is linked to the changing requirements of polymer processing. Several areas are likely to remain strategically important:
- Recycling and reprocessing: Recycled polymers can contain contaminants, fillers, moisture, or variable melt properties that increase wear and complicate processing.
- Advanced compounding: Twin-screw systems increasingly process high-performance blends, flame-retardant formulations, mineral compounds, and fibre-reinforced materials.
- Longer service life: Improved base materials, surface treatments, and bimetallic constructions can reduce downtime and maintenance frequency.
- Energy-efficient processing: Screw geometry and mixing design influence residence time, pressure, shear, melt quality, and drive-power requirements.
- Aftermarket engineering: Measurement, refurbishment, repair, and equipment modification remain valuable where customers operate diverse or older machinery.
- International supply: Export customers require consistent documentation, dimensional interchangeability, delivery reliability, and technical communication.
The company’s established focus on custom screw and barrel manufacture gives it a role in addressing these requirements. Its competitive performance will depend on metallurgy, process control, engineering accuracy, delivery capability, and the ability to adapt components to increasingly complex polymer formulations.
Summary
Zhoushan City Jinjiu Machinery Manufacture Co., Ltd. is a specialised Chinese manufacturer of screws, barrels, and related components for injection moulding, extrusion, rubber, chemical-fibre, and other industrial machinery. Based in Zhoushan’s Jintang machinery cluster, it serves a broad equipment range and combines standard production with custom design, measurement, repair, and modification services.
Its technical portfolio includes 38CrMoAlA steel components, nitrided and precision-finished parts, GH113 nickel-based alloy products, and welded-alloy or bimetallic constructions for demanding applications. The company’s significance lies not in the manufacture of complete plastics-processing systems, but in supplying the high-wear, precision-engineered components that directly influence polymer melting, conveying, mixing, throughput, and machine service life.
References
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CPS+ eMarketplace. (n.d.). ZHOUSHAN CITY JINJIU MACHINERY MANUFACTURE CO., LTD.ZHOUSHAN CITY JINJIU MACHINERY MANUFACTURE CO., LTD.. CPS+ eMarketplace. https://www.chinaplasonline.com/eMarketplace/ExhibitorInfo?CompId=1037784Link