Green sand casting, a centuries-old craft, is a fascinating blend of art and science, and brings forth five key points that illuminate the essence of this process.

At the heart of green sand casting lies the sand itself, a linchpin that exerts a direct influence on casting quality. The sand’s performance hinges on a delicate balance of characteristics—air permeability, wet strength, fluidity, plasticity, and yielding properties.

For wet sand applications, the choice of sand particle size is pivotal, with 55/100, 75/150, or 100/200 polygonal or round natural stone sands emerging as preferred options. These choices bestow enhanced surface strength and sand trapping resistance, essential for crafting superior castings. Moreover, when clay content remains consistent, bentonite emerges as a star player, boasting higher hot and wet tensile strength compared to ordinary clay. The magic continues with the addition of coal dust and wood chips, a recipe that not only enhances sand trapping resistance but also serves as a barrier against sand sticking, ensuring a smooth casting surface. Keeping moisture levels in check, around 6%, further elevates the sand’s overall performance.

However, the alchemy extends beyond sand selection. The order in which materials are introduced—old sand, new sand, clay, coal dust, and water—must be meticulously adhered to. Mixing and milling durations are set at 6 to 7 minutes, followed by a 5-hour blending phase. Post-blending, the sand undergoes sieving and loosening to optimize its air permeability and fluidity.

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