What is called swelling sand in casting? What are the consequences?
Expanding sand means that the inner and outer surface of the casting is partly swelled and the weight is increased.The causes of its occurrence:Because of the low strength and stiffness of the sand mold, the surface of the cavity will move back under the action of the filling metal liquid pressure, the expansion pressure or the expansion force of the graphite during the solidification process.Influence factor:1., core compactness is low or uneven, strength is low, sand box and core bone rigidity are low2., mixing sand uneven, type and core sand moisture is too high, poor mobility, wet strength is too high, so that the core and uneven strengthType 3., core underbaked or get damp, strength reduction4. pouring temperature is too high, casting speed is too fast, pouring system metal hydraulic head is too bigThe number of 5. types Zaton pores or vent, vent riser is not enough, improper location
Also called rising type, up box, casting size increased, or scrapped.
