Process flow
Scope of application
This code applies to special alloy silica sol investment casting.
Silica sol investment casting of other alloys can be implemented by reference.
Control requirements
Molding, assembly (tree), shell making, dewaxing, smelting and pouring, cleaning, heat treatment and finishing are the production processes of special alloy investment casting, and general process rules for each process should be formulated. The inspection is included in the inspection specification. Melt casting is recognized as a special process.
For each casting, a process flow is required.
The entire production process of castings should be produced in strict accordance with the requirements of the process code and process flow. Implement process control and make original records of the process by the requirements of the process code.
Wax mold making
Wax Treatment Process Operation
Wax treatment process: (stand still in the bucket) stand for dehydration → (in addition to the water bucket) stirring evaporation dehydration → (stand still in the bucket) stand for decontamination
Process parameters:
a. The temperature of the standing barrel is 85-90℃.
b. Standing time 6-8h.
c. The stirring temperature of the water tank is 110-120℃.
d. The stirring time is 10-12h.
e. The temperature of the standing barrel is 80-85℃.
f. Standstill time > 12h.
g. The insulation temperature of the incubator is 54±2℃ and the insulation time is more than 24h.
Operating procedure
1. Check whether the equipment and temperature control instruments are in normal working condition.
2. Pour the old wax liquid recovered from the dewaxing kettle into the filter tank for filtration; then send it to the standing barrel, and let it stand for 6-8 hours at a temperature lower than 85-90 °C.
3. After the settling water is discharged, pour the wax liquid into the dewatering bucket.
4. Remove the wax liquid in the bucket, keep it warm at 110-120℃ and stir to evaporate the residual water until there is no foam on the surface of the wax liquid.
5. Filter the wax liquid that has been removed from the water through a <60 mesh screen and then put it into a standing bucket at 70°C-90°C, and keep it at rest for more than 12 hours.
6. The remaining water and impurities at the bottom of the bucket should be regularly released in addition to the bucket and the standing bucket.
7. Send the recovered wax liquid processed in the static barrel to the insulation barrel of the die wax press machine for the main production die (runner).
8. According to the performance of the old wax material and the consumption of the wax material, add a proper amount of new wax to the stationary bucket from time to time, generally about 3%-5%.
9. Pour the qualified wax liquid into the wax tank in the incubator. To reduce the gas in the wax liquid in the wax tank, keep it for a period of high temperature at 80℃/2h and then drop it to 54℃. It can be used to press wax molds after being kept at 54±2℃ for 24h.
Precautions
1. In addition to the buckets, the standing buckets should be drained and drained in time.
2. Regularly check the working conditions of the temperature control instruments of each piece of equipment to prevent loss of control, especially to prevent the wax material from aging due to excessive temperature.
3. Check the liquid level of each heat transfer oil in the wax processing equipment once a month. The oil level should be about 200mm away from the top surface of the equipment to prevent oil from overflowing. And pay attention to checking the equipment for oil leakage.
4. Always check the environmental status to avoid dust and sundries mixed into the wax material.
Code of Practice for the Pressed Wax Modeling Process
Process requirements
Room temperature 24±3°C Wax tank temperature 48±2°C (large pieces should be set according to process requirements) Wax injection nozzle temperature 50-55°C Injection pressure 0.2Mpa-0.4 Mpa Pressure holding time 5-10s Cooling water temperature 2-10 °C
Operating procedures
1. Check whether the oil pressure, heat preservation temperature, operation buttons, etc. of the wax press are normal. Adjust the injection pressure of the wax press, the temperature of the wax injection nozzle, the pressure holding time, the cooling time, etc. according to the technical regulations.
2. Take out the wax tank from the incubator, install it on the wax press, and release the wax material mixed with air on the upper part.
3. Put the mold on the work table of the wax press, adjust the wax injection nozzle to make it consistent with the wax injection port of the mold, and check whether all the core pieces of the mold are in the correct position and whether the mold opens and closes smoothly.
4. Open the mold and spray a thin layer of a parting agent. Fit the shape and aim at the wax nozzle.
5. Press the button with both hands to press the wax mold.
6. Pull out the core, open the mold, and carefully remove the wax mold. Cool in cooling water or a storage tray as required. And check the wax model with the following defects should be scrapped: (1) wax model with serious bubbles; (2) wax model with unclear edges and corners; (3) wax model that cannot be repaired; (4) wax model whose size does not meet the requirements mold.
7. Remove the residual wax on the mold. Note that only the parting surface of the mold, the wax chips on the core, and the mold release agent can be blown off with compressed air. Metal tools are not allowed to scrape the cavity and pull the core. Prevent damage to the mold cavity.
8. Press the wax mold for the next time according to the above regulations, and then reciprocate the production.
9. Gently take out the wax mold from the cooling water in time, blow off the wax chips and water droplets with compressed air, carry out self-inspection, and put the qualified wax mold into the storage tray correctly.
10. Use a soft cloth to clean the mold after each shift or after the mold is produced on duty. If the mold is found to be damaged, it should be reported to the foreman immediately, and the foreman will handle it. And clean the wax press, tools, and the site to be clean and tidy.
Precautions
1. When pressing the wax mold, the first piece of inspection must be carried out, and the operation can be carried out after confirming that it is qualified. During the pressing process, the pressing parameters cannot be easily changed.
2. When using a new mold, be sure to understand the mold assembly and disassembly sequence, and the wax mold removal method.
3. When storing the wax mold, attention should be paid to the direction in which it is placed to prevent deformation. When necessary, measures such as jigs and fixtures can be taken to avoid the deformation of the wax mold.
4. Make 2-3 shrinkage rate samples per shift (such as Ø100X6mm round cake samples, etc.), measure the shrinkage rate after cooling, and make a record.
5. Dispose of the residual wax in the wax tank before leaving get off work. The waste wax mold and waste wax should be kept clean, put into the waste wax box, and sent to the wax processing section in time.
6. When the wax pressing machine is working, it is not allowed to hold the mold by hand or stretch your hand under the table, and it is not allowed to operate the button with one hand to prevent personal safety accidents.
7. Do a good job of fire safety in the wax mold room.
Code of Practice for Wax Pattern Dressing Process
Process requirements: room temperature 24℃±3℃
operating procedure
Before repairing the mold, it should be checked that the appearance of the wax mold is clear, the surface is smooth and smooth, there is no defect, the size meets the requirements, and there is no deformation.
Repair mold
1. Carefully and gently scrape off the flash or parting line along the surface of the wax mold with the edge of the blade, without damaging the wax mold. The small flash can also be directly wiped with a cloth.
2. Use repair wax to repair the depression of the wax model, and the surface should be smooth after repair.
3. The air bubbles on the wax mold must be broken and repaired with repair wax.
4. For castings with high requirements, the wax pattern wrinkles must be repaired and smoothed.
5. Use the compressed air nozzle to blow off the wax chips and place them in the storage tray as required.
6. Inspection after mold repair: check whether the wax mold is complete, whether it is deformed, whether the surface is rough, and whether the writing is qualified.
7. After the work is completed, clean up the site.
Precautions
1. The polished wax model must meet the relevant inspection requirements.
2. The repaired wax mold should be neatly placed in the storage tray as required to prevent deformation.
3. Do a good job of safety and fire prevention.
Sprue wax mold making
Process requirements
Room temperature 24℃±3℃ Injection wax temperature 48±2℃ Injection pressure 0.2-0.4Mpa Pressure holding time depends on the type of runner
operating procedure
Integral runner pressing
1. Check whether the air pressure of the wax press, the temperature of the heat preservation barrel, and the operation buttons are normal, and adjust the parameters such as the injection pressure of the machine according to the technical regulations.
2. Put the runner mold on the machine table, and check whether the wax injection nozzle of the machine is at the same height as the mold wax injection port and whether the mold opening and closing are smooth.
3. Open the mold, spray a thin layer of a parting agent, place the nut, close the mold, and aim at the wax nozzle.
4. Press the work button with both hands to suppress the sprue wax mold.
5. After pressing, pull out the core, open the mold, carefully take out the runner wax mold, and put it into cooling water. Note that defective ones should be scrapped.
6. Remove the residual wax from the mold.
7. Spray the parting agent, put the screw cap, fit the shape, and carry out the next pressing, to reciprocate the production cycle.
8. Take out the wax runner after cooling for 3-5 minutes, blow out the water droplets with compressed air, and place it in the designated position.
9. The equipment and molds should be cleaned up after each shift or after the molds are used.
Precautions
1. Do not spray too much parting agent in the mold cavity.
2. The surface of the wax runner should be smooth, and free of depressions, cracks, and seams. If the wax runner has defects such as cracks, depressions, and bubbles, it should be repaired, and those that cannot be repaired should be scrapped.
3. Do a good job in the safety of injection molding. It is strictly forbidden to open the compressed air into the cylinder when the cylinder head of the wax pneumatic cylinder is not tightened.
The wax mold workshop should do a good job of safety and fire prevention.
Wax model combination (group tree)
Wax model combination
Process requirements
Room temperature 24℃±3℃.
After welding, the minimum distance between the upper surface of the wax mold and the upper edge of the sprue cup is not less than 60mm. Wax pattern spacing after welding is 6-8mm (minimum 4mm with holes, the spacing between grooves is slightly about 10-12mm; gate length is 8-12mm.
Operating procedure
1. Visually inspect all wax patterns again to ensure 100% qualified.
2. Select the type of runner according to the casting technology regulations.
3. Check the wax runner (die head) to ensure that it is qualified.
4. Install a cleaned cover plate on the sprue cup of the qualified wax runner, and make sure that it is flat and seamless. If there is a gap, the gap should be ironed with an electric iron to prevent the slurry from flowing into the shell.
5. Solder with bonding wax or electric soldering iron. Place the wax runner (die head), weld the wax mold neatly and firmly according to the technical regulations, and stick it on the runner (die head).
6. On the sprue cup of the welded wax module, mark the identification mark according to the metal material specified by the process.
7. Use compressed air to blow off the wax shavings on the module. Hang the module on the transport vehicle and send it to the mold-washing process. When the work is done, clean up the site.
Precautions
1. The welding of the wax mold and the runner should be firm and seamless.
2. The wax molds welded on the same group of wax molds must be of the same material.
3. If there are wax drops on the wax model, the wax drops should be scraped off.
4. Pay attention to safety and cut off the power supply after work. And do a good job of fire safety.
Wax module cleaning
Process requirements
Wax pattern cleaner. Room temperature 24℃±3℃
Operation process
1. Prepare the cleaning solution in proportion and stir.
2. Remove the assembled wax module that has been standing for more than 45 minutes from the transport trolley, first fully immerse the module in the cleaning solution, reciprocate three times in a row for about 5s, lift the module, and drip the liquid.
3. Take out the wax module and use compressed air to dry or cool the module.
4. Hang the cleaned module on the transport trolley.
Spot check module cleaning effect:
1. Select two groups from the same batch of cleaned modules, immerse them in silica sol (add 0.5% wetting agent by volume), and carefully check whether they are completely wetted after pulling out.
2. It can be completely wetted, indicating that the cleaning effect is good. The module can be rinsed in water to remove the silica sol, blown off with compressed air, and hung on the transport trolley for use.
3. If the modules cannot be completely wetted, the whole batch of modules must be washed again.
Precautions
1. If the liquid level drops, replenish the new liquid in time. If there is white flake pollution, it should be placed for 24 hours, 2/3 of the clean solution is sucked out, the rest of the dirty solution is poured out, and a new solution is added, and it can be used again. (Generally, each cleaning solution can be used for about 40 days, more than 6000-8000 groups)
2. During the use of the cleaning solution, the fallen wax mold should be taken out in time. After use, remove all foreign matter and seal it with a cap.
3. There should be ventilation equipment in the module cleaning room, and the air should be circulated. And strictly prohibit fireworks, do a good job of safety and fire prevention.
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