1. Casting principle The parting surface should place the main cavity in the bottom box as much as possible, which is beneficial to the process design. The sand box has strong rigidity and eats less sand with balanced solidification. The thick part uses direct chilled iron or sand-insulated chilled iron to accelerate cooling. Get qualified organizations. The design principle of the pouring system is fast pouring, slag blocking, feeding shrinkage, economy, and easy cleaning. The inner gate shape is better with a pitch shape (rectangular or approximately square), easy to feed, and the filling temperature difference is small. The semicircular or triangular inner gate should not be provided with poor feeding effect. The center of the semicircular or triangular gate has strong heat preservation, and the joint between the center of the gate and the casting is easy to form shrinkage holes.
2. After filling, it solidifies quickly to improve the finish and internal density of the casting. No riser simplifies the process and saves the cost. The riser is as easy to operate as possible with dark pressure riser. If large parts are filled with an open riser, they must be manually ordered. (Metal supplement) The effect is great.
3. The production of ball milled iron castings should be controlled so that white mouths and hard edges cannot occur. Solutions:
(1) Control chemical composition
(2) Enlarge gates
(3) The molten iron temperature> 1450 ℃, increase the pouring temperature.
Precautions for molten metal pouring of ball-milled iron castings:
(1) Ladles, pouring materials, inoculants and spheroidizing agents for pre-furnace disposal must be fully dried before use, and can be used after drying.
(2) It is necessary for the pouring personnel to wear factory clothes and wear protective glasses as required, and the work site should be unobstructed. The molten metal in the ladle should not be too full to avoid spilling and hurting people during transportation and pouring.
(3) Choose the pouring speed correctly, that is, pouring slowly at the beginning to facilitate the alignment of the gate, reduce the impact of the molten metal on the sand mold and facilitate the discharge of gas; then pouring quickly to avoid cold isolation; it should be slow before it is full Pouring means following the criteria of slow, fast, and slow.
(4) Regarding the castings with relatively large liquidity shortening and condensation shortening, such as medium and large steel castings, make up pouring from the gate or riser in time after pouring.
(5) When pouring, the gas emerging from the mold should be ignited in time to avoid the occurrence of pores due to the holding of the mold, and the incomplete incineration of the gas will endanger human health and pollute the air.
The above is about the production details of ball milled cast iron production and pouring.