Machining Process of Machined Sand Casting Parts for Pump Bodies, Valve Bodies and Impellers in Pump and Valve Industry

In the field of pump and valve fluid machinery, Machined Sand Casting Parts serve as the mainstream forming solution for core components such as pump bodies, valve bodies and impellers. They balance the cost advantages of mass production and the precision requirements of precision assembly. Sand casting is compatible with common pump and valve materials including gray cast iron, ductile iron and carbon steel. Combined with CNC precision machining, it effectively solves industrial pain points of fluid equipment such as complex structures, high sealing requirements and strict operational stability, and is widely applied in water supply and drainage, chemical industry, HVAC, industrial fluid transportation and other scenarios.

The production of pump and valve Machined Sand Casting Parts consists of two core stages: sand casting blank forming and precision machining. Process control directly determines the pressure resistance, sealing performance and service life of the equipment. In the blank forming stage, resin sand and coated sand processes are mostly adopted. Compared with ordinary green sand, they deliver higher forming accuracy and fewer casting defects such as pores and shrinkage porosity, adapting to the special-shaped complex structures of pump body cavities, valve body flow channels and impeller blades. A standard machining allowance of 5-8mm is reserved according to component dimensions. After pouring, the castings undergo shakeout, riser cutting and stress relief annealing to eliminate internal stress thoroughly, preventing deformation and cracking during subsequent machining and long-term service, and ensuring the basic quality of casting blanks.

The machining process follows the principle of "rough machining first, finishing later and layered machining", with differentiated processing technologies adopted for pump bodies, valve bodies and impellers according to their working conditions. As pressure-bearing shell-type Machined Sand Casting Parts, pump bodies focus on the machining of flange end faces, mounting reference holes and internal flow channels. Rough milling is used to remove excess allowance, and finish milling ensures the flatness of end faces and the roughness of sealing surfaces, so as to guarantee the tightness of pipeline connection and prevent high-pressure fluid leakage. For valve body parts, precision machining is mainly carried out on valve seat sealing surfaces and valve core matching holes. Precision turning and boring processes are applied to strictly control dimensional tolerances, ensuring flexible valve opening and closing and reliable pressure tightness for high and low-pressure fluid working conditions.

As the core moving component of water pumps, impellers are the most difficult-to-process Machined Sand Casting Parts. Featuring complex curved blade structures, they require 5-axis CNC linkage machining to accurately trim blade curved surfaces, tip clearances and hub matching positions. This ensures consistent blade curvature, effectively reducing pump operating noise and improving fluid transportation efficiency. After machining, deburring and flow channel surface polishing are conducted to reduce fluid resistance and avoid impurity deposition that affects equipment operation.

A strict quality inspection process is implemented for all finished Machined Sand Casting Parts, including dimensional inspection, surface flaw detection, hydraulic pressure resistance testing and hardness testing to eliminate defects such as pores, deformation and dimensional deviation. Meanwhile, surface treatment processes like painting and plastic spraying are adopted on demand to improve the rust and corrosion resistance of components. The integrated sand casting and precision machining process retains the advantages of sand casting including low cost, adaptability to complex structures and suitability for mass production, while meeting the high-precision assembly and stable operation requirements of pump and valve equipment. It has become the most cost-effective and widely used production process solution in the pump and valve industry.