During the production process of nickel hard castings, molds are made effectively according to the product drawings of different shapes. The molds are effectively divided into upper and lower dies, which are completed through the comprehensive processes such as turning, creating, milling, etching and electric spark.The shape and size of the pit is the same as half of the product.As wax mold is mainly used for industrial wax molding, aluminum alloy with low melting point, low hardness, low requirement, low price and light weight is selected as the mold.
Nickel hard castings mainly use aluminum alloy mold to produce a large number of industrial solid core models.Under normal circumstances, one industrial wax solid core model can only correspond to one blank product.After finishing the wax mold's peripheral allowance, a number of single wax molds were glued on the pre-prepared mold head (also known as group tree), which was also the solid wax core model produced by end mold.
Nickel hard castings require the first layer of fine sand (refractory sand, high temperature resistant, usually silicon sand) to be sprayed evenly on the wax molds that have been fixed on the die head after applying industrial glue.The sand particles are small and fine, which ensures that the final surface of the blank is as smooth as possible.The wax mold sprayed with the first layer of fine sand is allowed to air dry naturally at the set room temperature (or constant temperature), but the shape of the wax mold cannot be affected. The time of natural air drying depends on the complexity of the product itself. Generally, the first air drying time of the precision casting is about 5-8 hours.
After the first sandblasting and natural air drying, continue to apply industrial glue (silica soluble slurry) on the surface of the wax mold and spray the second layer of sand. The size of the second layer of sand particles is larger and thicker than the previous layer of sand.After spraying the second layer of sand, let the wax mold air dry naturally under the set constant temperature.
After the second sand blasting and natural air drying, the third sand blasting, the fourth sand blasting, the fifth sand blasting and other processes.Requirements: adjust the number of sandblasting according to product surface requirements, volume and dead weight.In general, the number of sandblasting is 3-7 times.The size of each sandblasting is different, and the sand in the latter process is generally thicker than that in the former process, and the length of drying time is also different.Generally a complete wax mould on the sand production cycle for about 3-4 days.
Before baking, apply a layer of white industrial latex (silicon-soluble slurry) evenly to dry and solidify the sand mold, and seal the wax mold to prepare for the post-baking process.At the same time, after the baking process, it can also improve the brittleness of sand mold, easy to break the sand layer and take out the blank.