What is precision casting of stainless steel?

In the production of stainless steel products, some of the product shape is strange, unable to use the elbow and other processes for production, in order to produce this kind of irregular shape (internal for hollow or solid) products, using a wax mold do sand mold liquid material filling molding process.

Advantage: can make the product with changeful design according to different wax model.

Disadvantages: forming blank precision is not high, the surface roughness is large.

Process flow of investment casting

Make moulds according to different shapes of products. The die is divided into upper and lower concave die, which is completed through comprehensive processes such as turning, planing, milling, erosion and electric spark. The shape and size of the pit are the same as the half of the product. Because wax mold is mainly used for industrial wax pressure, so choose melting point is not high, not high hardness, low requirements, cheaper price, light weight of aluminum alloy materials do die.

A large number of industrial wax solid core models were produced by aluminum alloy die. Under normal circumstances, only one solid core model of industrial wax can be used to produce one blank.

After finishing the allowance around the wax mould and deburring, a number of single wax mould are glued on the prepared mould head (also known as group tree). This mould head is also a solid core model of industrial wax produced by wax mould. (appearance looks like a tree).

Apply industrial glue to several wax molds that have been fixed on the die head and spray the first layer of fine sand evenly (a kind of refractory sand, high temperature resistant, usually silica sand). The sand particles are very small and fine, so as to ensure that the final surface of the blank as smooth as possible.

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

After the first sand spraying and natural air drying, continue on the surface of the wax model on the industrial glue (silicon slurry), and spray on the second layer of sand, the size of the second layer of sand particles than the first layer of sand before the big, to the thick. After spraying the second layer of sand, let the wax mold 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 so on. Requirements:
-  According to the product surface requirements, volume size, weight and other corresponding adjustment sand blasting times. In general, the number of sand blasting is 3-7 times.

-  The size of sandblasting sand is not the same each time, usually after the process of sand than the previous process of sand coarse, drying time is not the same. Generally a complete wax mold on the sand production cycle is about 3 to 4 days.

Apply a layer of white industrial latex (silica slurry) to the finished sandblasting wax mold before baking, 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 in the baking process, but also improve the brittleness of the sand mold, easy to break the sand layer, take out the blank.

Baking process

The wax mold fixed on the mold head and completed the sandblasting and air drying process is heated in a special oven sealed with metal (usually a steam furnace burning kerosene). For industrial wax melting point is not high, the temperature at about 150 ゜, heated to melt wax models formed wax water flows along the gate, this process is to take off the wax. The dewaxed wax mold is just an empty sand shell. The key to precision casting is to use this empty sand shell. (Generally this kind of wax can be used many times, but the wax must be re-filtered, otherwise the unclean wax will affect the surface quality of the blank, such as: surface sand holes, pitting, but also affect the shrinkage of the investment casting products).

 Bake sand shell

In order to make the wax off the sand shell is more strong and solid, before pouring into the stainless steel water, must bake sand shell, usually at high temperature (temperature at about 1000 ゜) roasted in the fire

Pour the liquid stainless steel water that has been dissolved into liquid at high temperature into the dewaxed sand shell. The liquid stainless steel water will fill the space before the wax molding until it is fully filled, including the die head in the middle.

Because the stainless steel boiler will have different components of the material mixed, the factory must test the material percentage. Then adjust the needed proportion such as adding those aspects of the elements, to achieve the desired effect.

Liquid stainless steel water cooling solidification, To break up the outermost sand shell by means of a mechanical tool or a human hand, revealing solid stainless steel products is the original wax mold shape, which is the final need for the rough. Then one by one cutting, separation and rough grinding into a single blank

Inspection blank: the blank with sand holes and air holes on the surface must be repaired by argon arc welding.

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

Carry out other process until finished product.

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