Commonly used blanks for machining include castings, forgings, profiles and welded parts. Different blank types and the accuracy, roughness and hardness of the blank have a direct impact on the machining process. Some factors should be considered when selecting a valve blank:
(1) The material of the part and the organization and performance requirements of the material. The part materials specified on the design drawings generally determine the type of blank. For example, if the part material is cast iron, the casting method must be used to manufacture the blank. For steel parts, the mechanical properties of the material should be considered when selecting the blank. For example, parts for manufacturing high-pressure valves should generally be selected from forgings or welded parts to ensure good mechanical properties.
(2) The structural shape and external dimensions of the part. The structural switch of the part is an important factor affecting the selection of the blank. For example, the valve body with a complicated structure switch can be selected from castings. Large-sized valve bodies are available in sand casting; small sizes are investment-cast.
(3) The size of the production program. The larger the production program of the parts, the better the economical effect of the high-precision and high-efficiency blank manufacturing method.
(4) Conditions for the manufacture of blanks. The blanks should be selected according to the equipment and process level at the site, and advanced rough manufacturing methods should be gradually adopted taking into account the development prospects.