Without high quality mold sample absolutely impossible to get high quality disappearing mold casting. This is sanzhuji combined with disappearing mold casting process characteristics summed up experience, perfect mold sample with vacuum negative pressure system, casting the perfect casting. Vanishing mold casting mold material is optional copolymer resin beads, mainly using pentane as a foaming agent, the content of pentane directly affects the quality of the mold piece：
The main processes of pentane controlled.
Pre-foaming - bead maturation - die sheet drying
The process of pre-foaming is the process of expanding and foaming the beads on the one hand, and the main process of pentane dissipation on the other. The pentane is the basis of pre-foaming and molding, but when the molding is finished, it is expected that the pentane can be completely and completely dissipated.
Bead pre-foaming
If the original pentane of the beads is less than 9.5%, the heating time of the preform can be shortened, and it is recommended to control around 40s; if it is more than or equal to 9.5%, the heating time of the preform should be longer, and it may be controlled around 60s. The structure of the bead grain is broken in long prefermentation time, consuming too much foaming agent; thus affecting the quality of the secondary molding. STMMA preservation method: low temperature preservation ≤ 10 degrees. When it is not used up after opening, remember to re-tie the bag tightly and keep the barrel covered at low temperature to prevent the loss of pentane.
Bead grain maturation
The negative pressure inside the freshly foamed bead grain is easy to collapse, so it must be put into maturation bin to let the air enter the inside of the bead grain to achieve the balance inside and outside. Maturation is a process for the pre-foamed beads to reach stability, and the changes of the beads in this stabilization process: most of the water evaporates, the beads recover a certain elasticity, and the content of pentane is reduced. When the content of pentane is less than 9.5%, the maturation time of the pre-haired beads is generally controlled as 12-48 hours. When the content of pentane is more than 9.5%, the maturation time of pre-grown beads is generally controlled as 3-4 days. In this maturation process the pentane content is controlled at 7%-8% to reduce the possibility of swelling bubbles in the later stage after the beads are formed. At this time, the mold piece is filled evenly, easy to be formed, the surface of the mold piece has high finish and strength, and the bead grain is integrated with the bead grain. The shrinkage size of the die sheet is stable and consistent. When the pentane content is lower than 5% after the beads are matured, it is very difficult to form the die sheet, the surface collapses, shrinks, and the uneven surface has no finish.
The higher the temperature, the faster the pentane evaporates.
The higher the temperature, the faster the pentane evaporates. When the mold is placed in the air for natural maturation, the pentane and water content evaporate slowly. According to my many years of production experience: the normal situation of the mold sheet maturation 1 day, sent to the drying room temperature control between 45-50 degrees, baked to 4-5 days sent to detect the pentane content. If the pentane content is greater than 5%, continue to high temperature maturation, less than 5% can be used. If the pentane content of the mold sample is greater than 5%, the dipping coated mold sample is wrapped by the coating even if the high temperature drying gas is difficult to evaporate out. In the pouring process caused by the amount of gas is too large, so that the internal and external air pressure imbalance caused by the back spray, collapse box. Castings produce porosity, air partition, defective castings lead to scrap.
Qingdao Sanzhuji Equipment Manufacturing Co., Ltd. specializes in the production of sand reclamation equipment,foundry machines,Sand casting equipment,GS high efficiency rotary mixer,no-bake resin sand mixer,Jolt squeeze molding machine/Jolt-squeezing moulding machines,Multi- Piston Moulding Machine/Hydraulic multi-piston moulding machine,foundry molding machine,flaskless moulding machine,shot blasting machine,dust collector,according to the amount of old sand recovered Carry out plan customization, and provide sand reclamation equipment installation, commissioning, and training. Welcome guests to visit the factory.
