Testing in sand casting is about predictability, performance, safety, and meeting design specifications and requirements
Foundry melt labs conduct a range of tests to ensure the quality, structural integrity, and performance of cast components and the materials used in the casting process. Testing is critical to the success of the overall casting process.
Testing involves several stages, including pre-production, in-process, and post-production.
Material Testing ensures the alloy used for the casting meets industry, government, and customer specifications.
Chemical analysis determines the chemical composition of the molten metal to ensure it meets the specified requirements. Chemical analyses can also be used to predict casting microstructures, machinability, weldability, and corrosion resistance in certain applications.
Mechanical testing evaluates the physical and mechanical properties of the material, such as tensile strength, yield strength, elongation, impact strength, hardness, and galling resistance.
Metallographic examination analyzes the microstructure of the metal under a microscope to assess properties like grain size, phase distribution, and potential internal flaws.
Corrosion testing assesses the metal’s resistance to corrosion and degradation in various environments.
Sand Testing assesses the properties of the sand used in the molding process to ensure it has the correct characteristics for creating a mold and preventing defects. This includes tests for:
Grain Fineness: Determining the size distribution of the sand particles.
Moisture Content: Measuring the amount of moisture in the sand.
Loss on Ignition: Analyzing the amount of unwanted organic material in the sand.
Permeability: Evaluating the ability of the compacted mold to allow air to pass through.
Strength: Determining the compression, shear, and tensile/bending strength of the molding and core sand.
Melt Quality Control and Pouring Analysis monitors the solidification behavior, cooling rates, and phase transformations of the molten metal to detect defects early.
Temperature monitoring: Checking molten metal temperatures prior to pouring to ensure metal is within the proper range. This helps prevent defects like misruns, cold shuts, or inclusions.
Pouring time and technique are monitored to avoid turbulence, which can cause porosity.
Product Inspection and Non-destructive Testing (NDT) occurs post-production and is used to detect internal or surface flaws without damaging the part.
Visual Inspection: Visually examining the casting for surface defects like cracks, tears, and porosity.
Dimensional Inspection: Checking if the casting meets the specified dimensions and tolerances, often using Coordinate Measuring Machines (CMMs).
Liquid Penetrant Testing (PT): Identifying surface cracks and other flaws by applying a colored liquid that seeps into the defects and becomes visible under a developer.
Magnetic Particle Testing (MT): Detecting surface and near-surface defects in ferromagnetic materials by magnetizing the component and applying ferrous particles which accumulate at defect locations.
Ultrasonic Testing (UT): Using high-frequency sound waves to detect internal defects and measure material thickness.
Radiographic Testing (RT): Employing X-rays or gamma rays to examine the internal structure of castings for defects like shrinkage, cracks, and inclusions.
Eddy Current Testing (ECT): Detecting surface cracks and measuring conductivity and material thickness in conductive materials using electromagnetic induction.
Pressure Testing: Assessing the leak-proof nature of castings required for leak-proof applications by pressurizing them with gas or fluid.
Testing in sand casting isn’t just about quality – it’s about predictability, performance, safety, and meeting design specifications and requirements. Detecting defects early not only protects the performance and safety of a casting, it reduces the time and cost associated with the casting process.
Badger Alloys’ Testing and Research & Development Departments offer extensive on-site testing and quality assurance capabilities. With cutting-edge testing equipment and years of training and experience, our certified professionals provide this critical service on site on our manufacturing campus in Milwaukee. Our goal is always to provide our customers with world-class castings. If you have questions about Badger Alloys’ testing capabilities, please contact Nick Hanson, sales engineer, at nickh@badgeralloys.com/414.258.8200.
