Name: China Carbon Steel Screw Spike Manufacturers Suppliers Factory - Free Sample - GNEE RAIL
Brand: GNEE
SKU: 294942563

Description

Technical Parameters

↵Rail Screw Spike Fastening System

A railway screw spike is a large-format threaded steel fastener that converts torque into tensile preload through a plastic dowel embedded in concrete or timber - unique among all rail fasteners as the only device that generates clamping force through elastic bolt stretch rather than spring deflection, the only fastener whose residual tension cannot be measured by torque wrench after 3 months in service, and the only component where the load-bearing interface is not steel-on-steel but steel-on-polymer (PA66/GF)

Technical Specifications:

Parameter	Physical Mechanism	Typical Value / Threshold	Field Detection	Consequence
PA66 thread form	Stress distribution	Root radius 0.25–0.35 mm	Thread gauge	Sharp root → thread strip at 60% torque
Fiber orientation	Injection vs machined	Shear 80 vs 45 MPa	Destructive test only	Machined dowel → strip at 130 Nm vs 200 Nm
Wet installation	Friction coefficient	μ 0.12 dry; 0.32 wet	Torque only (blind)	40% under-tension; rail creep >3 mm/year
Dowel creep	Polymer relaxation	30–35% loss @ 10 years	Lift-off test only	Torque reads OK; tension low
Thread corrosion	Carbonation wicking	Pitting 0.1–0.2 mm/year	Removal only	Head twists off during maintenance
Bending fatigue	Thread runout stress	45–95 MPa; limit 70 MPa	Torque-angle monitoring	Head separation; no visible warning

Performance Range:

PA66 Thread Form Optimization - Screw spike thread is not standard ISO metric. DIN 7998 / EN 13481-2 specifies: 60° included angle, 0.25–0.35 mm root radius, 0.6–0.8 mm flank clearance. Purpose: distribute shear stress along dowel length, avoid creep rupture at first engaged thread. Standard bolt thread (sharp root) in PA66 dowel → stress concentration factor 4.2 → thread strip at 60% of design torque.

Glass Fiber Orientation Anisotropy - PA66+30%GF dowels are injection-moulded. Fibers orient perpendicular to flow direction at thread roots - parallel to shear plane. This orientation provides maximum thread shear strength (80–90 MPa) . Machined dowels (cut from stock) have random fiber orientation → shear strength 45–55 MPa. Visual identical; performance not equivalent. Procurement error: machined dowels substituted → thread strip at 130 Nm vs 200 Nm spec.

Maintenance & Operational Perspective

Embedded Corrosion (Invisible) - Concrete is alkaline (pH 12–13). Steel in contact with concrete passivates (0.01 mm/year). BUT: water wicks down thread helix from rail seat. At 20–40 mm depth, pH drops to 9–10 (carbonation). Active corrosion initiates in thread roots. Pitting rate: 0.1–0.2 mm/year. Section loss >20% → torsional shear failure during removal. Detection: impossible; only removal reveals.
Bending Fatigue at Thread Runout - Rail seat transverse vibration induces alternating bending moment at spike head-shank junction. Maximum bending stress occurs at thread runout (first full thread) . Stress ratio R = −1 (fully reversed). Fatigue limit: grade 8.8 = 70 MPa @ 5M cycles. Track measurement: actual stress 45–95 MPa. 50% exceed fatigue limit. Failure: head separation, no plastic deformation. Detection: torque-angle monitoring; angle increase >40° indicates crack.