Water glass sand casting molding

(1) Determine the position of the pattern in the casting sand mold

Select a flat bottom plate and a sand box of appropriate size according to the shape. Wipe the pattern before molding, so as to avoid the sand casting sand sticking to the pattern during molding and damaging the cavity during mold lifting.

(2) Sand filling and pounding

When molding, the layer close to the pattern shall be filled with surface sand. Generally, the thickness of surface sand after tamping is 75 ~ 100mm. When filling sand into the sand box, hold the pattern by hand and plug the sand casting sand around the pattern to prevent the pattern from moving and the sand casting sand around the pattern from being loose.

Sand mold casting sodium silicate sand has good fluidity. It can be compacted manually during modeling and core making. After compaction, it can be scraped flat with a scraper. It can then be hardened with CO2 gas.

(3) Exhaust of sand mold for sand casting

In order to smoothly discharge a large amount of gas generated in the mold cavity during pouring, in addition to pricking vent holes above, the three feeding risers placed above the rim are also conducive to exhaust.

(4) Positioning and opening of sand mold in sand mold casting

In order to ensure that the upper and lower mold can be closed accurately according to the position when opening the mold, the positioning pin (sleeve pin method) is used to locate the casting sand mold.

When opening the mold, you must be serious and careful. The upper mold must be lifted vertically, otherwise the workload of mold repair will be increased. When opening the mold, first use a rubber hammer to knock slightly left and right on the handle of the upper sand casting sand box, so as to create a small gap between the mold cavity and the pattern, so as to avoid damage to the mold cavity during opening.

(5) Mold lifting

Before mold lifting, use a duster pen to dip some water to slightly wet the periphery of the pattern, which is conducive to mold repair after mold lifting. Nail the mold lifting needle above the center of gravity of the pattern, otherwise the cavity will be damaged during mold lifting.

After nailing the mold lifting needle, tap the lower part of the mold lifting needle laterally with a small hammer to make a uniform gap between the pattern and the mold cavity for mold lifting. However, it should be noted that the pattern should not be loosened too much, otherwise it will increase the error and sometimes damage the casting sand mold. Crane can be used to lift the formwork. If the cavity of the upper and lower mold is damaged, it shall be repaired with a mold repair tool.

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