Manufacturing Challenge: Ø840mm Marine Bronze Bushings for a U.S. Customer
We recently produced a batch of large-size marine bronze bushings for a customer in the United States.
This project included an outer diameter of 840 mm, and each bushing required a center cut, which brought several unique engineering and manufacturing challenges.
--- 1️⃣ Mold Strength & High-Temperature Stability At this diameter, the casting mold is subjected to extreme thermal and mechanical stress. Cracking risks are significantly higher. To ensure stability, our engineering team worked closely with our mold partners to redesign: mold material strength reinforcement structure cooling layout A reliable mold is the foundation of accurate lead time. Any mold failure can delay the entire project.
--- 2️⃣ Stress Relief for Large-Size Castings Because of the massive size, these bushings cannot be heat-treated inside a furnace. Instead, we performed on-site stress relief right after casting to minimize deformation and ensure long-term dimensional stability.
--- 3️⃣ Dimensional Accuracy & Deformation Control Large bronze castings have high thermal expansion and shrinkage. To guarantee final tolerances, we implemented: custom fixtures & supports for both inner and outer diameters rough machining → natural cooling → re-alignment → final machining vertical storage for 24 hours to avoid gravity deformation protective packaging using 10 mm foam to prevent transport damage This process ensures both precision and repeatability for oversized bushings.
--- 4️⃣ Material Control & Process Optimization For alloys such as ZCuAl10Fe3, impurity content must be strictly controlled (≤1.0%) to maintain mechanical performance. Working temperature should remain below 250°C to avoid strength loss. We also adjusted the casting process depending on wall thickness to reduce internal defects and cracking risk Conclusion Large-diameter bronze bushings are not only a machining challenge-they test the entire supply chain, from mold design to casting, stress relief, and precision machining.
At RAMSHIN, we continue improving our capability in large-size bronze components, ensuring stable quality and reliable delivery for our global customers.
