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Lost foam casting casting site operations need to pay attention to what
- Jan 16, 2018 -

In the lost foam casting process, the entire process includes seven links, each link for the quality of lost foam casting has a significant impact on the casting process is the entire EPC process a crucial part of the master pouring Process considerations, strict control casting process every detail is the key to the production of high quality lost foam castings.

Lost foam casting casting process is filled with molten steel, while the foam mold vaporization disappear process. The whole process needs attention is:

(1) runner from beginning to end should be filled with molten steel, if dissatisfied, due to the coating layer strength is very limited, prone to sand collapse and air intake phenomenon, resulting in casting defects.

(2) pouring liquid steel must ensure that stability, accurate, fast. Fill the sprue cup instantaneously, and achieve rapid and constant flow, tons of molten steel in about a minute. If the same box of molten steel cut-off will be sucked into the air, it may cause sand collapse or castings increased porosity problems, leading to scrapped castings.

(3) Lost Foam Casting is closed with negative pressure and must be closed below the sprue cup. Molten steel into the mold, which began liquefied combustion, and gasification disappeared, the liquid front short distance to form a temporary cavity, so the design of molten steel filling speed and foam model disappear at about the same speed. In order to prevent the liquid steel from melting high temperature radiation with other models of the same runner, the runner is a little farther from the cast model. The position of the vertical sprue chooses the lowest position of the whole box casting. Pay attention to adjust the vacuum pouring and vacuum control within a certain range, after pouring to maintain a certain negative pressure for a period of time, negative pressure to stop the liquid steel out of the box after condensation.

Back spray is a phenomenon often found in lost foam casting. Serious back-injection may endanger the safety of the pouring workers and must be taken seriously. To reduce the spray phenomenon, the following measures can be taken:

First, foam modulus density is small, to ensure the quality of the foam surface, to ensure the strength of the model premise, the foam should be done as low as possible to reduce the amount of gas in the pouring.

Second, the foam mold must be dried before the paint, foam mold each batch should be sampling the drying process of weight changes, make a change in the weight curve of baking, weight only in the case of no longer change before coating.

Third, the pouring system, especially the sprue and runner, should not be coated, so that the gas generated during pouring can be quickly and adequately pumped away without coating, thereby saving the consumption of paint. Lastly, a baffle is placed over the sprue cup to block the molten steel from the back spray so that it can not splash out and threaten the on-site operator.

Using the above method can effectively prevent the phenomenon of back spray in the process of lost foam casting, better prevent the defects of castings and improve the quality of the castings, besides, it can also improve the safety of production.

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