Specifications
| Parameter | Value |
|---|---|
| Material | AISI 316L / CF3M, duplex 2205 (ASTM A890 4A), super duplex 2507 on request, nickel aluminium bronze CuAl10Ni5Fe4 |
| Process | Silica sol investment casting + CNC boring, facing and line drilling of the bearing axis |
| Tolerance | As-cast ISO 8062-3 DCTG 5-6; bearing bore to H7, concentricity within 0.03 mm |
| Surface finish | As-cast Ra 3.2-6.3 um; machined bore Ra 1.6 um or better; passivated after pickling |
| Weight range | 8 kg – 60 kg per piece |
| Heat treatment | Solution annealing 1040-1120 C water quench, duplex grades solution annealed and quenched to avoid sigma phase |
| Inspection | CMM and bore gauge reports, ultrasonic testing (UT), dye penetrant (PT) on all load paths, radiography of the boss to arm junction, EN 10204 3.1 certification |
Key features
- Bearing bore line bored to H7 so pintle bushes press in with controlled interference and no field line boring.
- Cast-in reinforcing fillets at the arm to boss junction reduce stress concentration in a historically crack-prone area.
- Duplex and super duplex options give roughly double the yield strength of 316L, allowing slimmer arms in the same load class.
- Seawater galvanic compatibility is managed by matching the gudgeon alloy to the rudder stock and bush material.
- Cored lubrication channels deliver grease directly to the bearing face, extending service intervals between dry dockings.
- Near net shape casting keeps machining allowance to 1.5-2 mm, cutting material removal and lead time on large units.
- Serialised parts with a permanent low stress stamp for lifetime traceability in the ship’s steering gear record.
Applications
- Rudder blade gudgeons and pintle housings on cargo vessels, tankers and bulk carriers
- Spade and semi-balanced rudder installations on offshore support vessels
- Workboat, tug and pilot boat steering gear retrofits
- Yacht and superyacht rudder bearing carriers
- Naval and coast guard vessel steering gear refurbishment
- Azimuth thruster and steering nozzle support castings
Quality and compliance
Rudder gudgeons are manufactured under IATF 16949 process control with full chemical and mechanical verification on an EN 10204 3.1 certificate. NDT scope, mechanical test coupons and final dimensional inspection can be witnessed by IACS member class societies including DNV, ABS, LR, BV, CCS, NK and RINA when specified on the purchase order.
FAQ
Q1. Can you machine the bearing bore to accept a specific bush supplier’s dimensions?
Yes. Send the bush drawing or the finished bore dimension with tolerance, and we machine and inspect to bore gauge before shipment. We can also fit and pin the bush as a sub-assembly.
Q2. Do you recommend 316L or duplex 2205 for a gudgeon?
For most coastal and harbour service 316L is adequate and economical. For ocean-going vessels, high rudder loads or long dry dock intervals, duplex 2205 gives a much higher yield strength and better pitting resistance, and is often the class-preferred option.
Q3. How do you confirm the casting is sound at the highly loaded boss?
Every production part receives dye penetrant examination on the load path, plus ultrasonic testing or radiography of the boss to arm junction. Test reports are included in the documentation package.
Q4. What information do you need to quote?
Send the drawing or 3D model, material grade, quantity, required NDT level and any class-society requirements. If you only have a sample, we will scan it and produce a manufacturing drawing for approval.
Q5. Can you supply matched gudgeon and pintle sets?
Yes. We cast and machine gudgeons, pintles and bearing bushes as a matched set, bore them on a common axis and verify fit before packing, which avoids alignment problems during installation.
Q6. Do you provide class approval documentation?
We provide the EN 10204 3.1 certificate, NDT reports and dimensional records needed for class review, and we can coordinate third-party or class-society witness and release on request.
Talk to Wendy She – sales@cnsandcasting.com – WhatsApp +86-13777124360
