The importance of epc casting coatings

25-07-2019

消失模铸件涂料的重要性

       In the process of mass transfer through the coating of epc casting, the cooperation of liquid and volume differentiation products exists and competes with each other.If the liquid differentiator is wetted too quickly and the cap is completely coated, the atmosphere and volume differentiator will aggregate between the liquid metal and the coating, and the resulting pressure will delay the metal's movement and even cause cold insulation.On the contrary, if the gas escape coating is too fast and the liquid differentiated product wetting and infiltration into the coating is too slow, the metal activity will be too fast and the liquid differentiated product will be involved in the active metal liquid, which will eventually constitute the defects of pores and general situation (Liuetal.,1997).On the other side of the coating is the sand, which is injected and shaken in time to coat the foam mold supported by the machine to protect it from deflating or breaking.During the casting process, the coating receives both the compressive stress from the sand and the compressive stress from the gases and liquids that arise from the differentiation of the active metal and the foam mold.

1.Die forging (also known as solid forging) is a kind of forging process with almost no margin.A patent on the craft was issued in 1958 (Shroyer, 1958), but its rapid growth and use are still in the last 20 years, widely used in casting aluminum, cast iron and steel, especially in the production of a large number of vehicles and Marine engine block cylinder head and other parts show its superiority.Die forging is similar to the size and shape of the casting foam mold, coated with common refractory coating and dried, buried in dry sand vibration appearance, then pouring, high temperature liquid metal to make mold liquefaction and amiable, and occupy the position of the original foam mold, solidification and cooling to form the casting.Because of its inhere characteristics, the general situation of the castings get brightness is far higher than commonly used traditional forging and sand mould forging of clay sand, core don't demand, not parting, sand not adhesive, easily of liquidation, the casting is good, can be used for forging such as huge policy motivation of cylinder head and cylinder body favor product ideas more comfortable degree.

消失模铸件涂料的重要性

Some are positive interaction effect, appropriate ratio can play a synergistic strengthening result, some are negative interaction effect, the ratio imbalance will play an antagonistic offset effect.Therefore, the result of coating formulation is not the sum of all kinds of self-supporting results and effects.The total effect of a reasonable formula is greater than the sum of the effects of self-reliance, and the total effect of a divergent formula is less than the sum of the effects of self-reliance.The permeability of 4class medium temperature zone has applicable cost nearly all the articles about vanishing die forging coating, the "coating permeability function" of vanishing die forging coating is said to be "air permeability".In the production theory, we can investigate that the coating after casting has changed the color, becoming a painted face or black face bao zheng, which is due to the foam mold in the mold cavity maltreatment occurs free carbon through the coating, crowded out the mold cavity, adhere to the coating general situation.We can also see when the cross-sectional area of the permeable pores of the coating is large (many articles describe strong air permeability) or when the absolute value of the vacuum is drawn too high.

At this point, gasification of foam when cold and consolidated into liquid materials, molding sand bond shaping.Under the condition of vacuum extraction, the pressure difference in the atmosphere makes the molding sand as firm as the stone, this paper discusses the coherent topic of the coating used by the vanishing die forging method with the premise of foam mold, dry sand and vacuum extraction.The author thinks that there are three ways to use foam forging, although foam die is gone, but in China's air, as long as there are foam, dry sand, vacuum three technological conditions of forging should be called die forging.Die forging there are three kinds of technology die forging from the beginning of 80 years in the last century into China's future, has experienced a long period of chaos, the industry has spread: seemingly simple die forging, a look, a waste!As a self-reliant craft way, die forging should have its own actual basis, just because we overlooked the impact of die forging unique practical research.