High-Quality Extruded Rod Factories & Products

Centerline porosity in POM acetal rods is caused by volumetric shrinkage as the molten core cools and solidifies slower than the already-hardened outer skin. In poorly controlled extrusion, the interior is pulled outward, leaving micro-voids along the central axis that can lead to catastrophic cracking or fluid leakage when drilling center holes. SHUNDA prevents centerline porosity by employing copolymer POM resins with controlled melt flow indices, low-speed high-pressure vacuum extrusion sizing dies, and extended multi-zone oil-bath cooling. Furthermore, our post-extrusion annealing cycle stabilizes the core crystallite matrix, ensuring an ultra-dense, void-free cross-section verified by non-destructive ultrasonic flaw testing.

Cast MC Nylon (Monomer Casting PA6) is preferred whenever components require large outside diameters (>100mm up to 800mm), higher load-bearing capacity, and maximum wear resistance under heavy compression. Because MC Nylon polymerizes directly inside atmospheric molds without thermal melt shear, it attains a significantly higher molecular weight and a higher degree of crystalline order than extruded nylon. This produces higher surface hardness, superior elastic modulus, and lower internal residual stresses, making it ideal for massive crane sheaves, large gear rings, and structural slide guides. Extruded PA6/PA66 is typically chosen for smaller precision turned components (Ø 5mm - 100mm) produced in high-speed automated CNC lathes where continuous stock feed and high flexural toughness are needed.

Unprotected polyamides absorb ambient atmospheric humidity (up to 2% at 50% RH and over 7% at saturation), causing swelling and radial dimensional shifts before machining. To eliminate this issue, our export-ready procedures require all precision rods to be dried post-annealing and immediately sealed in multi-layer aluminum-foil vapor barrier bags with industrial silica gel desiccants. Pallets are reinforced with corner edge-protectors, shrink-wrapped with waterproof stretch films, and banded to heat-treated ISPM-15 export-compliant wooden crates. For sensitive applications, we can also pre-condition stock to equilibrium moisture content prior to dispatch.

Plastics possess low thermal conductivity and low elastic moduli compared to metals; heat buildup causes localized softening and gummy surface tearing. When turning POM and Nylon rods, use high-speed steel (HSS) or finely polished uncoated tungsten carbide (C2 grade) inserts with positive rake angles (top rake 15° to 25°, clearance angle 10° to 15°). Maintain sharp, mirror-polished cutting edges with a nose radius of 0.4mm - 0.8mm. Cutting speeds should range between 250 and 500 m/min with feeds of 0.15 to 0.4 mm/rev. Use flood coolant (water-soluble oil emulsion) or dry pressurized air vortex nozzles to evacuate continuous ribbon chips and prevent chip wrapping around the spinning spindle.

Yes. Our twin-screw compounding lines formulate custom polymers containing solid lubricants (PTFE, graphite, MoS2), structural reinforcing fibers (10% - 30% chopped glass fiber or carbon fiber), antistatic/carbon black masterbatches (surface resistivity 10^3 - 10^9 Ω), and thermal stabilizers. For color matching, we cross-reference RAL and Pantone color standards via automated spectrophotometers, ensuring batch-to-batch chromatic uniformity for OEM branding, electrical phase identification, or food-safety visual optical sorting (e.g., corporate ultramarine blue).

Every dispatch includes a comprehensive QA documentation dossier containing: 1) An EN 10204 3.1 Certified Factory Material Inspection Certificate, detailing actual polymer melt flow index (MFI), density (ISO 1183), tensile yield stress (ISO 527), and Rockwell hardness (ISO 2039); 2) RoHS 3 and REACH compliance verification statements; 3) Full-lot outer diameter and ovality laser micrometry inspection logs; and 4) Optical/ultrasonic flaw verification sign-offs. If requested, FDA food-contact declaration certificates and raw monomer supply-chain origin records are provided.