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22
2021
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Foundry: How to inspect the quality of pump body castings?
Foundry
Foundry: The inspection of pump body castings mainly includes dimensional inspection, visual inspection of appearance and surface, chemical composition analysis, and mechanical property tests. For pump body castings that are more important or prone to problems in the casting process, non-destructive testing is also required. Non-destructive testing techniques that can be used for quality inspection of ductile iron castings include liquid penetration testing, magnetic particle testing, and eddy current testing.
Foundry: Pump body The inspection of castings mainly includes dimensional inspection, visual inspection of appearance and surface, chemical composition analysis, and mechanical property tests. For pump body castings that require more importance or are prone to problems in the casting process, non-destructive testing is also required. Non-destructive testing technologies that can be used for quality inspection of ductile iron castings include liquid penetration testing, magnetic particle testing, and eddy current testing.
(1) Liquid Penetration Testing
Liquid penetration testing is used to inspect various open defects on the surface of pump body castings, such as surface cracks and surface pinholes, which are difficult to detect with the naked eye. The commonly used penetration testing is color detection, which involves spraying a colored (usually red) liquid (penetrant) with high penetration ability on the pump body. casting On the surface, the penetrant penetrates into the open defects, quickly wipes off the surface penetrant layer, and then sprays a quick-drying developer (also called developer) onto the surface of the pump body casting. After the penetrant remaining in the open defects is absorbed, the developer is dyed, which can reflect the shape, size, and distribution of the defects.
(2) Eddy Current Testing
Foundry: Eddy current testing is suitable for inspecting defects generally no more than 6-7MM deep below the surface. Eddy current testing is divided into two types: placement coil method and pass-through coil method. When the test piece is placed near a coil through which alternating current is passed, the alternating magnetic field entering the test piece can induce a current (eddy current) flowing in an eddy current shape perpendicular to the excitation magnetic field in the test piece. The eddy current will generate a magnetic field opposite to the direction of the excitation magnetic field, which will partially reduce the original magnetic field in the coil, thereby causing a change in the coil impedance.
(3) Magnetic Particle Testing
Foundry : Magnetic particle testing is suitable for detecting surface defects and defects a few millimeters deep below the surface. It requires DC (or AC) magnetization equipment and magnetic powder (or magnetic suspension) to perform the testing operation. The magnetization equipment is used to generate a magnetic field on the inner and outer surfaces of the pump body casting, and the magnetic powder or magnetic suspension is used to display defects.
Pump body, casting, foundry
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