The minimum wall thickness for investment casting can reach 0.3 mm.
This process can produce complex precision castings, achieving ultra-thin wall structures through wax pattern forming and precision casting techniques, making it suitable for precision parts manufacturing.
Process Characteristics
Investment casting uses a wax pattern press, refractory coating, and dewaxing processes to create the mold cavity, which is then poured into the mold using molten metal. Its core advantages include:
High dimensional accuracy: Castings can achieve dimensional accuracy of 5-7, with a surface roughness of Ra25-6.3μm;
Flexible structure: Complex structures such as fine grooves and curved holes can be cast;
Lightweight: A single casting can weigh as little as a few grams, making it suitable for lightweighting needs.
Applications
It is commonly used in the manufacture of high-precision components such as aircraft engine blades and precision mechanical parts, combining complex designs with lightweight advantages.
Why is a minimum wall thickness specified for castings?
The primary purpose of specifying a minimum wall thickness for castings is to prevent cold shuts and under-casting defects during the casting process. Too thin a wall thickness can prevent the molten metal from filling the mold cavity, potentially resulting in unfused or incompletely filled defects. Excessive wall thickness can lead to coarse grains, shrinkage cavities, and shrinkage porosity, resulting in reduced mechanical properties.
Avoiding Cold Shuts and Undercasting
The minimum wall thickness ensures sufficient flow distance and residence time for the molten metal, preventing premature solidification and underfilling of the mold cavity. For example, the minimum wall thickness for cast iron is typically 0.5-1.0 mm, while cast steel may require a thicker wall (e.g., 1.5 mm or greater).
Controlling Grain Size and Mechanical Properties
Increasing wall thickness prolongs cooling time, leading to the formation of coarse grains and reduced material strength. Excessively thin wall thickness, however, can result in fine grains and insufficient strength. For example, in sand casting, the minimum wall thickness is typically at least one-third of the casting thickness.
Adapting to Differences in Casting Processes
Different processes (e.g., sand casting and die casting) have different wall thickness requirements. Die castings typically require thinner walls (e.g., starting at 0.5 mm) due to mold clearance limitations, but they must be constructed with high-fluidity alloys (e.g., aluminum alloys). Of course, if you have large-volume casting needs, you can partner with Mulan Metal. With 12 years of casting experience, we’ve helped clients in over 30 countries complete their casting operations and have earned widespread recognition. We look forward to hearing from you.
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