Casting pores prevention

Casting pores prevention
1, for complex thin-walled castings, to improve the precision casting shell permeability, where possible, can be set at the highest point of the vent. A reasonable set of gating system, prevent pouring volume of gas, and is conducive to the cavity gas emissions.
2, an appropriate increase in pouring temperature, to minimize ladle pouring cup from the mouth to reduce the casting speed, so that a smooth liquid metal filling, to prevent the involvement of gas, so that the cavity in the gas and the liquid metal can be smoothly discharged.
3, dewaxing mold material should be excluded clean, residual mold material should be minimized.
4, firing shell to the full, should be high enough temperature; sol and ethyl silicate shell 950 to 1100 degrees Celsius, the water glass shell 850 to 900 degrees Celsius; holding time is greater than & ,, to ensure precision casting shell through roasting, gas evolution substance fully excluded. Roasting complete shell is white or pale gray, there should be no dark spots.
   Sol physicochemical parameters mainly by: SIO2 content, density, Na2o content, PH value, kinematic viscosity, colloidal particle diameter, these physical and chemical parameters affecting the powder-liquid ratio main shell strength, stability and paint coatings. Wuxi foam concrete
  Because precision casting business is difficult to detect these physicochemical parameters, so that on the one hand to strengthen the supply side of the selection, evaluation and confirmation.
  On the other hand, the surface layer and the backing layer should choose to use different sizes of silica, the surface layer of silica select S-830, S-1430 Select the backing layer of silica sol. Coatings formulated in precision casting method will directly affect the quality of the casting, that we first understand the preparation of the coating. Usually before adding silica coating formulation, coupled with a wetting agent mix of refractory powder is added with stirring, and finally add defoamers. In order to ensure quality when coating, surface coating all of the new material, mixing time should be greater than 24h can be used, as part of new ingredients, mixing time can be shortened to 12h. Transition layer and a backing layer coating stirring time may be less than the surface-layer coating, with all new paint is stirred for longer than 10h, part of the new feature, the stirring time can be shortened by half. With a good paint if not used, it should be capped to prevent evaporation. Best not with paint in Shell operations, and set up a special coating formulation equipment.

Products

Aluminum alloy precision casting

Stainless steel castings

Stainless steel castings

Stainless steel castings