Lost foam casting is a casting process that has almost […]
Lost foam casting is a casting process that has almost no machining allowance and can be formed.
The process is to bond and combine foam models into model clusters, apply and brush special refractory coatings and dry them, then bury them in a special negative pressure sand box and realize the conversion of vapor-liquid into entities, that is, modeling. Under certain conditions The molten metal is poured down to make the model gasify and disappear, the molten metal occupies the position of the model, and the required casting is formed after condensation, and the casting is close to the process technology without flash and burrs.
Backspray is a common phenomenon in lost foam casting. If the backspray is serious, it may endanger the personal safety of the caster. It must be paid attention to. In order to reduce the spray phenomenon, the following measures can be taken.
(1) The density of the foam model should be small. Under the premise of ensuring the quality of the foam surface and the strength of the model, the lighter the foam should be, the better, in order to reduce the amount of gas during pouring.
(2) The models of the foam molding machine must be dried before coating. Each batch of foam models should be checked for weight changes during the drying process, and a baking weight change curve chart should be made. Only when the weight no longer changes. Paint.
(3) The lost foam pouring system, especially the straight runner and cross runner, should not be coated, so that the gas generated during pouring can be quickly and fully removed without coating, which saves the consumption of coatings.
(4) Cover a baffle plate on the top of the sprue cup, which can block the molten steel that is sprayed back up, so that it cannot splash out and endanger the on-site operators.