RTM variable speed sand mixer is developed and put into market by France Fondarc in 1990s. This machine has the advantages of high reliability, good mixed sand quality, high efficiency, and low operation cost. It is very suitable to match with upscale automatic molding lines.
The sand mixing principle of RTM mixer is different with other rotor type or rotary bottom plate type mixers. The basic principle of RTM mixer is: use the driving method of planetary rotor structure; different number of rotors (3-4 rotors) will be equipped according the mixer size and capacity. |
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◆ There is no obstacle in the whole sand mixing area, so rotors can rotate inside smoothly. Meanwhile, because of both rotation and revolution of rotors, there is no dead spot during mixing process and the mixed sand is homogeneous, loose with good feel; ◆ The shape of each rotor is different, so the sand can be fully stirred during mixing process; ◆Additives such as bentonite can cover the sand grain more homogeneously, so the molding sand has not only good quality but also excellent flowing and filling ability without increasing sand temperature; ◆ Mixer’s efficiency can be brought into full play. It can reach the 80%-100% of the nominal sand mixing efficiency (The efficiency is also influenced by pre-treatment level of return sand, quality of original sand and bentonite, etc.); ◆ It can effectively decrease the loss of casting scrap due to variable molding sand quality; ◆ It can effectively decrease the quantity of additives, thus decrease material cost; ◆ Because of the speed change, equipment’s energy consumption is lower, and wear and tear is less, therefore equipment operation and maintenance cost can be significantly decreased. ◆ The installation type is flexible, especially the filling of additives. One method is to add different kinds of additives into the electronic scale above mixer; another method is to premix additives and then use pneumatic transport to press into mixer directly. By this way additives can be filled more quickly and homogenously. |
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