Before coating and hanging the surface layer, check whether the cleaned module has dropped parts, and check whether it is completely dry.
Check whether the viscosity of the coating and the rotating speed of the equipment meet the requirements, and adjust them if they are abnormal
Remove the module from the transport trolley, and rotate the module slowly into the coating slurry of the surface layer at an angle of about 30 degrees. Pay attention to minimize the air in the coating at the groove and sharp corner of the wax mold. Brush or blow off the air bubbles with a brush or compressed air if there is a cast word or groove. Prepainting.
Take out the module at a slightly faster speed to remove the excess paint, blow the bubbles wrapped in the holes and sharp corners of the wax mold with compressed air, rotate the module at different angles continuously, and form a complete and uniform coating on the module. If the uniform and complete coating cannot be obtained, it is necessary to re dip the slurry.
Extend the evenly coated module into the sand shower and turn it over, so that all surfaces are evenly coated with a layer of sand.
Take out the module and hang it on the transport trolley. When the whole vehicle is fully hung, push it to the appropriate position to let the surface layer shell dry to the time specified in the technology.
The dried module of the surface shell is transported to the shell making workshop of the transition layer.
Take down the module and check the internal angle of the mold shell. Check whether the hole is completely dry. If there is any wrinkle or crack in the coating, make another treatment immediately.
Remove the module and shake off the surplus floating sand.
Immerse the module in the silica sol, take it out within 2 seconds and drop it for about 5 seconds.
Slowly immerse the module without any pre wetting agent into the coating of transition layer at an angle of about 30 degrees for 3-4 seconds, take out the module at a slightly fast speed and keep rotating, and remove the redundant coating to form a uniform coating. If there is coating blocking and accumulation at the hole, compressed air or brush can be used to open it.
Extend the module into the floating sand bucket to lay sand. When there is sand on the edge of the gate cup, slowly pull out the module and shake off the surplus sand. There should be no area that has not been covered by sand by visual inspection. If there is any coverage, use the hand to assist the sand laying until it is even.
Hang the module on the transport trolley, after the whole vehicle is fully hung, push it to the drying area for more than 8 hours.
Push the trolley to the back coating, remove the module and shake it gently to remove the loose floating sand on the mold shell.
Carefully immerse the module in the back coating barrel and turn it gently for at least 10 seconds.
Take out the module to let the excess paint drip, and hang it on the upper frame of the sizing machine during continuous operation. Let the coating drop back to the slurry barrel, then remove the module, keep rotating to make the coating uniform. Pay attention to the coating at the edge of the gate cup not too thin.
Extend the module into the floating sand bucket to lay sand. When the edge of the gate cup has reached the sand, slowly pull out the module to shake off the surplus sand, hang the module back to the trolley, and push it to the drying area for the specified time to fully dry.
Repeat the above steps to coat the second and third layers of the back layer with sand and seal the slurry after it is fully dried. Note that the drying time of sealing slurry is usually relatively longer.
After the coating and hanging of each layer, the site shall be cleaned in time and the equipment shall be cleaned for maintenance.
Strictly control the humidity, temperature, wind speed and paint viscosity of the shell making workshop.
The surface layer shall be carefully made to ensure that there is no bubble between the coating and wax mold at the deep hole and sharp corner, no coating accumulation, paste hole and other phenomena. The surface layer shell shall not be placed in front of and behind the fan after just making it. It shall be noted that the drying speed of the surface layer and filter layer shall not be too fast, and the drying time shall not be too long, so as to prevent cracking defects.
Shake off the previous layer of sand before making the next layer.
Wax chips and other sundries on the coating surface shall be removed frequently.
During the drying of the back layer, the air flow between the modules and the dehumidification function shall be in the best condition.