The tide type is preferred

When the wet type can not meet the requirements of the use of table dry sand type, dry sand type or other sand type.
The following conditions should be noted when considering the application of wet type:
(1) When the casting is too high and the metal static pressure exceeds the compressive strength of the wet type, the dry sand type or self-hard sand type should be considered.
To specific analysis: if the wall of the casting is thin, although the casting is very tall, but the tendency of rising sand, sticky sand, running fire is small. This restriction can be relaxed appropriately. Because before the end of pouring, even the highest metal shell has condensed on the lower surface of the casting. In addition, the use of high quality sodium bentonite sand or activated bentonite sand, its sand type wet pressure strength is higher, for the casting of the larger gradually create conditions.
(2) When the casting has a large horizontal wall on the casting position, the wet type is easy to cause the sand clamp defects, so other sand types should be considered.
(3) The sand type with long modeling process or long waiting for pouring should not be wet. For example, under the conditions of complex casting, many sand cores, long lower core time and large size of the casting, the wet type will be dried for too long, reducing the surface strength and prone to sand flushing defects. Therefore, the wet type should generally be poured on the same day. If you need to pour the next day, the upper and lower half of the empty box should be built to prevent water loss. Open the box before pouring the next day, open the lower core, and then pour the box. Longer processes should be considered for other sand types.
(4) When more cold iron is placed in the type, the wet type should be avoided. If there is ling iron in the wet type, the cold iron should be preheated in advance, and put into the type in time, so as to avoid the cold iron and condensing "water drops", and cause air hole defects after pouring.
When the wet type is considered to be unreliable, the table dry sand type, sand type only surface drying, according to the size of the casting and wall thickness, the drying depth is 15~18mm. It has many advantages of wet type, but the performance is better than wet type, reducing the tendency of pores, sand, sand, sand. Mainly used for manual or machine-shaped medium and large pieces.
For large castings, the resin can be applied from the hard sand type, water glass sand type and clay dry sand type. Precise size, smooth casting can be obtained with resin, but the cost is high.