This method is very much used and most suitable for split patterns as well as for solid patterns. One half of the pattern is placed with its flat side on molding board, and a drag is rammed and rolled over. It is now possible to place the other half of the pattern and a cope box in proper position. After ramming, the cope is lifted off and the two halves of the pattern are rapped and drawn separately. The cope is next replaced on the drag to assemble the mold.
Advantages Of Air Refrigeration : 1. The refrigerant used namely air is cheap and easily available. 2. There is no danger of fire or toxic effects due to leakages. 3. The weight to ton of refrigeration ratio is less as compared to other systems. Disadvantages Of Air Refrigeration : 1. The quantity of Refrigerant used per ton of refrigeration is high as compared to other systems. 2. The COP of the system is very low. Therefore running cost is high. 3. The danger of frosting at the expander valves is more as the air contains moisture content.
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