Ningbo Ruican produces cast tug towing pin seat bodies for harbour tugs, escort tugs, workboats and offshore support vessels, combining an ASTM A216 WCB carbon steel structural body with an ASTM A128 Mn13 high-manganese wear insert at the pin contact zone. The heavy-duty pin bore, deck-mounting base and bolt pattern are finish machined in-house, so the seat body installs directly on the winch foundation without secondary fitting. Silica sol lost wax casting holds ISO 8062 CT4-CT6 accuracy on the bore and base geometry, while the Mn13 insert work-hardens under tow-line impact to extend service life in abrasive, high-shock duty.
Key Features
- Heavy-duty machined pin bore — CNC boring holds bore diameter to H7/H8 with coaxiality controlled to 0.05 mm, keeping the towing pin true under full line pull.
- ASTM A128 Mn13 work-hardening wear insert — high-manganese steel work-hardens from roughly 200 HB as-cast to 450-550 HB in service, absorbing repeated tow-line shock without cracking.
- Deck-mounting base with machined footprint — base face milled flat and the bolt pattern drilled, reamed and spot-faced to the foundation drawing, eliminating on-board shimming.
- Replaceable insert design — wear insert supplied as a bolt-on or weld-in element so the seat body can be refurbished at drydock instead of replaced.
- Integrally cast ribbing and load path — the pin bore housing, ribs and base are cast as one near-net-shape component, removing weld joints from the primary load path.
- Verified casting integrity — magnetic particle and ultrasonic inspection on the bore housing and base-to-column transition, with documented acceptance against the customer’s NDT level.
Materials & Heat Treatment
| Material | Standard | Condition | Application note |
|---|---|---|---|
| Carbon steel WCB | ASTM A216 WCB | Normalized and tempered, or quenched and tempered per drawing | Structural body, deck-mounting base and pin bore housing for standard towing winch duty |
| High-manganese steel Mn13 | ASTM A128 Grade B / Mn13 (1.3401) | Water quenched (solution treated) at 1050-1100 C | Work-hardening wear insert in the pin contact and guide surfaces |
| Carbon-manganese steel | ASTM A216 WCC / ASTM A352 LCC | Normalized, or normalized and tempered | Higher strength bodies and low-temperature service for northern or arctic-class hulls |
| Low-alloy cast steel | ASTM A148 Grade 80-50 | Quenched and tempered | Heavy-duty and escort tug winches with elevated shock and fatigue loading |
| Hardfacing overlay (optional) | Customer-specified wear alloy | As-welded, finish ground or machined | Additional build-up on pin seating faces where line abrasion is most severe |
Specifications
| Parameter | Value |
|---|---|
| Casting process | Silica sol investment casting (lost wax); water glass route offered for larger, cost-driven part families |
| Casting weight range | 18 kg – 320 kg per piece (typical towing pin seat body 45 – 160 kg) |
| Dimensional tolerance | ISO 8062 CT4-CT6 (silica sol process); CT7-CT8 available via the water glass route |
| Minimum wall thickness | 8 mm nominal for structural walls, thinner locally after engineering review |
| As-cast surface roughness | Ra 6.3 – 12.5 µm, improved to Ra 3.2 µm on machined bore, base and sealing faces |
| Machining capability | CNC horizontal boring and milling, CNC turning and drilling; pin bore to H7/H8, bore coaxiality 0.05 mm, base flatness 0.10 mm per metre, bolt holes reamed to drawing fit |
| Wear insert hardness | Mn13 insert approx. 200 HB as water-quenched, work-hardening to 450-550 HB in service |
| Inspection and testing | CMM dimensional layout, hardness mapping, magnetic particle inspection, ultrasonic testing, dye penetrant on machined surfaces |
| MOQ | 50 pieces per part number for series production; prototype and single-piece validation runs negotiable |
| Tooling lead time | 25-35 days for wax die, core tooling and first article samples |
| Production lead time | 40-55 days after sample approval, depending on volume and machining content |
Applications
- Harbour and escort tug towing winch pin seat assemblies
- Azimuth stern drive (ASD) and tractor tug towing pin units
- Workboat, barge and dredger towing hook and towing pin installations
- Offshore support vessel and anchor handling tug deck equipment
- Shipyard newbuild packages and drydock replacement of worn towing gear seats
Product Gallery
Quality & Documentation
Ningbo Ruican operates an IATF 16949 certified quality management system, and every towing pin seat body programme runs under documented process discipline: controlled melting practice, solidification simulation before tooling release, defined gating and feeding, and full heat-lot traceability from charge material through heat treatment to the packed part.
Process selection — silica sol vs. water glass. Silica sol investment casting is the recommended route for towing pin seat bodies because the pin bore, base footprint and bolt pattern demand CT4-CT6 accuracy and clean, sound sections at the highly loaded bore-to-base transition. Water glass casting is offered for larger seat bodies and simpler geometries where tolerance is less demanding and unit cost is the priority. The process route is confirmed with the customer at quotation stage against drawing tolerance, annual volume and total cost targets.
Documentation supplied:
– EN 10204 3.1 material certificates covering chemical analysis, mechanical properties, heat-treatment condition and hardness for both the WCB body and the Mn13 insert (EN 10204 3.2 certification arranged on request)
– First Article Inspection (FAI) dimensional reports against ballooned drawings, with CMM data for every drawing-numbered characteristic
– Non-destructive testing records: magnetic particle inspection, ultrasonic testing and dye penetrant results retained per batch
– Weld procedure and welder qualification records for insert attachment where weld-in construction is specified
– Third-party inspection options including SGS, BV, TUV, and marine classification society attendance (DNV, ABS, LR, BV, CCS) for witness testing and document review
Why Ningbo Ruican
- 17 years of casting experience supplying marine, industrial and automotive components to export customers worldwide.
- One-stop casting plus CNC machining in a single facility, protecting pin bore alignment, base flatness and datum integrity while shortening lead time and removing split-vendor risk.
- OEM and ODM programmes from drawings or samples, covering tooling design, casting simulation, prototyping, validation lots and series production.
- IATF 16949 certified quality system, delivering documented process control, full traceability and repeatable series delivery performance.
Request a Quote
Send your drawings to Wendy She — sales@cnsandcasting.com | WhatsApp +86-13777124360
