How to Choose Coating Process for Coated Sand Casting Manufacturers

How to Choose Coating Process for Coated Sand Casting Manufacturers

film sand that is, when the surface of sand grains is covered with a layer before modeling. Solid resin film the molding sand or it's core sand, there are two kinds of film coating process:

first, the cold method, the cold method is to dissolve the resin with ethanol, and then add urotropine in the process of sand mixing, so that both are coated on the surface of the sand, and finally the ethanol volatilizes, you will get coated sand;

second, thermal method, coating sand foundry will preheat the sand first to a certain temperature, then add resin to melt it, and then fully stir to let the resin is coated on the surface of the sand particles, and finally the urotropine aqueous solution and lubricant are added to obtain the coated sand by cooling, crushing and screening. General coating sand the process is mainly used for casting steel castings and iron castings.

In fact, the film is now covered sand film coating used by foundry manufacturers sand there are already three methods for the preparation process. These three are cold coating, temperature coating and thermal coating. Among them, the most commonly used by manufacturers is thermal coating, thermal coating has low numerical dosage and high production efficiency. Etc. Advantages.

1, cold coating process, the original sand and the thermosetting powdered phenolic resin is added to the sand mixer and stirred evenly, and then an appropriate amount of solvent is added to continue mixing until the powdered resin is completely melted and stuck on the surface of the sand particles and the solvent is volatilized, wait until the sand is broken and screened. But this method will take a long time to mix sand, the consumption of solvent is also very large, and the volatilized solvent gas is very easy to explode, this leads to the use of cold coating process is very small, almost unnecessary.

2. The temperature coating process, the temperature coating process is relatively simple, that is, the thermosetting liquid phenolic resin is mixed with 60-80 ℃ raw sand, and the sand is produced after 2-3 minutes, after cooling, crushing and screening, it is enough.

3. Thermal coating process. This thermal process is to first heat the raw sand to a certain temperature, and then put resin and urotropine aqueous solution and calcium stearate into the raw sand to mix and stir evenly, and then After cooling, broken and sieved. Because of the difference in casting equipment and proportion required, the mixing process is also different.

Film sand when the foundry factory stores the coated sand, it will put the film sand put it in a well-sealed bag or container, at room temperature less than or greater under the drying condition of 20 ℃, it can be stored for about 0.5-1 years. Film sand if the storage time is too long, it is easier to have local caking. If the caking is not very serious, the caking place can be mashed and used after screening.