The sprocket segment is the drive wheel of the crawler undercarriage: its teeth engage the track bushings and transmit the full propulsion torque of the excavator into the track chain. On large machines the sprocket is built from bolted cast segments precisely for this reason — when a segment wears or cracks, the operator replaces one segment instead of the entire wheel, and the machine returns to work in hours, not days.
Ningbo Ruican manufactures excavator sprocket segments by investment casting in 35CrMo alloy steel (AISI 4135 equivalent), delivering the tooth profile and mounting-bolt geometry near net shape before finish CNC machining. The casting route is the correct one for this part: a solid cast segment has continuous grain flow through the tooth roots — the point where fatigue cracks start in welded or fabricated designs — and heat treatment is controlled so surface hardness and core toughness are balanced for abrasive, impact-laden duty.
Segments are supplied quenched and tempered, with the tooth flank optionally induction hardened to 45–52 HRC for extended wear life, and bolt holes machined to drawing so a new segment bolts up without fitting work in the field. We produce segments for 12-ton to 80-ton excavator classes, for OEM production and for aftermarket undercarriage rebuilders.
Key Specifications
| Parameter | Specification |
|---|---|
| Material | 35CrMo alloy steel (AISI 4135 / DIN 1.7220 equivalent) |
| Manufacturing Process | Silica sol investment casting + CNC machining |
| Heat Treatment | Quenched & tempered 229–302 HB; tooth flanks optionally induction hardened 45–52 HRC |
| Casting Tolerance | ISO 8062 CT5–CT6 |
| Tooth Count / Pitch | Per OEM drawing (ISO 22628 / customer geometry) |
| Segment Weight | 15–120 kg depending on machine class |
| Finish | Shot blasted, machined bolt faces, anti-rust primer on request |
| Inspection | CMM tooth profile check, MT crack detection, EN 10204 3.1 material certificate |
| MOQ | 20 pieces upward; matched sets (full circle = 2–4 segments) supplied balanced |
| Applications | Excavators 12–80 t, track loaders, drilling rigs, tunnel shields |
Why Cast Segments Outperform Weld-Fabricated Ones
Tooth breakage on sprockets almost always begins at weld attachment points or at the heat-affected zone around them. A single-piece cast segment eliminates those welds entirely; the teeth and root are one continuous structure with fine-grain 35CrMo properties. Because investment casting reproduces the tooth flank close to finish size, minimal stock is removed in machining and the hardened case depth stays uniform — giving aftermarket rebuilders a segment that wears like the OEM part at a fraction of the price.
Why Choose Ningbo Ruican
- 17+ years casting undercarriage and drive components for construction and mining machinery
- IATF 16949 certified quality management with PPAP documentation for OEM-linked programs
- Integrated casting + CNC + heat treatment under one roof — one accountable partner for tooth geometry, hardness and bolt fit
- Matched-set logistics: segments for one full sprocket shipped together with controlled batch identity
- Alloy program: 35CrMo, 42CrMo4, 40Cr, cast steels and ductile irons on request
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