Production Process of Investment Castings

The wax mold sprayed with a layer of fine sand is allowed to air dry naturally at the set room temperature (or constant temperature), but the shape change of the internal wax mold cannot be affected. The time of natural air drying depends on the complexity of the product itself. Generally, the air drying time of an investment casting is about 5-8 hours.

After the primary sand is sprayed and naturally air dried, the surface of the wax mold is further coated with industrial glue (silica slurry), and the second layer of sand is sprayed. The particle size of the second layer of sand is larger and coarser than that of the previous layer of sand. After spraying the second layer of sand, let the wax mold dry naturally at the set constant temperature.

After the second sand blasting and natural air drying, the third sand blasting, the fourth sand blasting and the fifth sand blasting shall be carried out in sequence. Requirements: - Adjust the blasting times according to the product surface requirements, volume size, self weight, etc. Generally, the number of sandblasting is 3-7- The size of sand grains for each sandblasting is different. Generally, the sand grains of the next process are coarser than those of the previous process, and the air drying time is also different. Generally, a complete wax mold sanding production cycle is about 7-15 days.

Before the baking process, the wax mold that has completed the sand blasting process shall be evenly coated with a layer of white industrial latex (silica slurry) to bond and solidify the sand mold and seal the wax mold, so as to prepare for the next baking process. At the same time, after the baking process, the brittleness of the sand mold can be improved, so that the sand layer can be easily broken and the blank can be taken out.

In the baking process, the wax mold fixed on the mold head and completed the sand blasting and air drying process is put into a metal enclosed special oven for heating (usually a kerosene burning steam furnace). As the melting point of industrial wax is not high, and the temperature is about 150 ° C, wax mold is heated and melted to form wax water flowing out along the gate, which is called dewaxing. The wax mold after wax removal is just an empty sand shell. The key of investment casting is to use this empty sand shell. (Generally, this wax can be used repeatedly, but the wax must be re filtered, otherwise the unclean wax will affect the surface quality of the blank, such as surface sand holes and pits, and also affect the shrinkage of precision casting products.).

To make the dewaxed sand shell more solid and stable, the sand shell must be baked before pouring stainless steel water, usually in a high temperature (about 1000 ℃) stove.

Pour the stainless steel water that has been dissolved into liquid at high temperature into the dewaxed sand shell, and the liquid stainless steel water fills the space for wax mold forming until it is completely filled, including the mold head in the middle.

The factory must detect the percentage of materials because different components of materials will be mixed in the boiler that dissolves stainless steel. Then release according to the required proportion, such as adding those elements to achieve the desired effect.

After the liquid stainless steel water is cooled and solidified, the outer sand shell can be broken with the help of mechanical tools or manpower. The exposed solid stainless steel products are the original wax mold shape, which is the final required blank. Then cut, separate and rough grind one by one to form a single blank.

Inspection of blanks: blanks with sand holes and air holes on the surface must be repaired by argon arc welding, and those with serious defects must be returned to the furnace after cleaning.

Blank cleaning: the qualified blank must go through the cleaning process.

Carry out other processes until the finished product.