Customized Investment Casting / Precision Casting Parts
Features
Investment castings have high dimensional accuracy, generally up to CT4-6 (CT10~13 for sand casting, CT5~7 for die casting). Of course, due to the complexity of the investment casting process, there are many factors that affect the dimensional accuracy of castings, such as mold The shrinkage of the material, the deformation of the investment mold, the change of the line amount of the shell during the heating and cooling process, the shrinkage rate of the alloy, and the deformation of the casting during the solidification process, etc., so although the dimensional accuracy of ordinary investment castings is high, but its The consistency still needs to be improved (the dimensional consistency of castings using medium and high temperature waxes should be improved a lot).
Advantage
The biggest advantage of investment casting is that due to the high dimensional accuracy and surface finish of investment castings, machining work can be reduced, and only a small amount of machining allowance can be left on parts with higher requirements, and even some castings only There is a grinding and polishing allowance, and it can be used without machining. It can be seen that the investment casting method can greatly save machine tool equipment and processing man-hours, and greatly save metal raw materials.
Another advantage of the investment casting method is that it can cast complex castings of various alloys, especially superalloy castings. For example, the blades of jet engines, whose streamlined outline and inner cavity for cooling, can hardly be formed by mechanical processing technology. The investment casting process can not only achieve mass production, but also ensure the consistency of the castings, and avoid the stress concentration of the remaining knife lines after machining.
Process
Precision casting process
1. Make molds according to different shapes of products. The mold is divided into upper and lower dies, and is completed through comprehensive processes such as turning, planing, milling, etching, and electric sparks. The shape and size of the pit are consistent with half of the product. Because the wax mold is mainly used for industrial wax pressing, the aluminum alloy material with low melting point, low hardness, low requirements, cheap price and light weight is used as the mold.
2. Use aluminum alloy molds to produce a large number of industrial wax solid core models. Under normal circumstances, an industrial wax solid core model can only correspond to a blank product.
3. Refining the margin around the wax model, and sticking multiple single wax models to the pre-prepared die head after deburring. This die head is also an industrial wax solid produced by the wax model. core model. (It looks like a tree)
4. Coat the multiple wax patterns fixed on the die head with industrial glue and evenly spray the first layer of fine sand (a kind of refractory sand, high temperature resistant, usually silica sand). The sand particles are very small and fine, which ensures that the surface of the final blank is as smooth as possible.
5. Let the wax model sprayed with the first layer of fine sand dry naturally at the set room temperature (or constant temperature), but it cannot affect the shape change of the internal wax model. The natural drying time depends on the complexity of the product itself. The first air-drying time of the casting is about 5-8 hours.
6. After the first sand spraying and natural air drying, continue to apply industrial glue (silicon solution slurry) on the surface of the wax model, and spray the second layer of sand. The particle size of the second layer of sand is larger than that of the previous first layer of sand Come big, come thick. After spraying the second layer of sand, let the wax model dry naturally at the set constant temperature.
7. After the second sandblasting and natural air drying, the third sandblasting, fourth sandblasting, fifth sandblasting and other processes are carried out by analogy. Requirements: - Adjust the number of blasting times according to product surface requirements, volume size, self-weight, etc. Generally, the number of sandblasting is 3-7 times. - The size of the sand grains in each sandblasting is different. Usually, the sand grains in the subsequent process are thicker than the sand grains in the previous process, and the drying time is also different. Generally, the production cycle of sanding a complete wax model is about 3 to 4 days.
8. Before the baking process, the wax mold that has completed the sandblasting process is evenly coated with a layer of white industrial latex (silicon solution slurry) to bond and solidify the sand mold and seal the wax mold. Prepare for the baking process. At the same time, after the baking process, it can also improve the brittleness of the sand mold, which is convenient for breaking the sand layer and taking out the blank.
9. Baking process Put the wax mold fixed on the mold head and completed the sandblasting and air-drying process into a metal-tight special oven for heating (commonly used is a steam oven burning kerosene). Because the melting point of industrial wax is not high, the temperature is about 150 ゜. When the wax mold is heated and melted, wax water flows out along the gate. This process is called dewaxing. The wax model that has been waxed off 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 repeatedly, but these waxes must be filtered again, otherwise the unclean wax will affect the surface quality of the blank, such as: surface sand holes, pitting, and also affect the shrinkage of precision casting products).
10. Baking the sand shell In order to make the wax-free sand shell stronger and more stable, the sand shell must be baked before pouring stainless steel water, usually in a very high temperature (about 1000 ゜) furnace. .
11. Pour the stainless steel water that has been dissolved into liquid at high temperature into the wax-free sand shell, and the liquid stainless steel water fills the space of the previous wax mold until it is completely filled, including the middle part of the mold head.
12. Since materials of different components will be mixed into the stainless steel boiler, the factory must detect the percentage of materials. Then adjust and release according to the required ratio, such as increasing those aspects to achieve the desired effect.
13. After the liquid stainless steel water is cooled and solidified, the outermost sand shell is smashed with the help of mechanical tools or manpower, and the solid stainless steel product exposed is the shape of the original wax model, which is the final required blank. Then it will be cut one by one, separated and rough ground to become a single blank.
14. Inspection of the blank: the blank with blisters and pores on the surface must be repaired with argon arc welding, and if it is serious, it should be returned to the furnace after cleaning the waste.
15. Cleaning blanks: The blanks that pass the inspection must go through the cleaning process.
16. Carry out other processes until the finished product.
| Description | Auto Flange |
| Dimension | 240x85x180 |
| Technician | Investment casting |
| MOQ | 1000pcs |
| Production Schedule | 30 days |
Features
1. Mature technology, small dimension tolerance, stronger structure.
2. Carefully select raw materials, sufficient materials, smooth and shiny surface, to meet customer different needs.
3. The surface is flat and free of air holes, the structure is compact and fastened, and the workmanship is meticulous.
4. Years of industry production experience, different specifications can be customized on demand.
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