Vacuum Molding Machine V Process Molding For Big Castings By Using Dry Sand

V-process molding (also known as vacuum sealed molding) is a precision sand molding technology that uses vacuum negative pressure to fix dry sand molds without traditional binders, additives or water. A vacuum molding line integrates mold making, sand filling, compaction, mold closing, pouring, cooling and mold breaking into an automated production system, which maximizes the technical advantages of V-process molding and realizes efficient, stable batch production. Below is a detailed explanation of its core capabilities and typical industrial applications.

The vacuum molding line’s capabilities are rooted in the unique vacuum-driven molding principle, and the automated line design further amplifies its precision, efficiency and environmental performance. Its key capabilities are as follows:

• The line uses plastic film with high thermal shrinkage and good sealing (e.g., EVA film) to form a tight copy of the mold surface under vacuum. The dry sand is free of binders, so there is no sand sticking, chemical reaction or thermal expansion shrinkage of the mold during pouring.
• Castings produced have a Ra 6.3~12.5μm surface roughness, accurate dimensional tolerance (CT7~CT9 grade), clear contours and no flash/burrs. The line’s automated mold clamping and positioning system ensures consistent mold matching accuracy, avoiding dimensional deviation caused by manual operation.

• The molding sand is 100% dry silica sand without binders, water, clay or curing agents, eliminating the emission of harmful gases (e.g., formaldehyde, phenol) and dust during molding and pouring—there is no wastewater or waste residue from sand mixing.
• The vacuum system recycles the plastic film (optional for high-temperature resistant films) and the dry sand can be recycled at a rate of over 95% after simple screening and cooling, realizing zero waste of molding materials and complying with modern industrial low-carbon and environmental protection standards.

• A complete vacuum molding line is equipped with automated stations: mold lifting/rotating, film heating/sucking, sand hopper feeding, vibrating compaction, vacuum chamber sealing, mold closing and pouring conveying. The whole process is controlled by PLC, with reduced manual intervention (only for feeding and inspection).
• For medium and small castings, the line can achieve a molding cycle of 3~15 minutes per mold (adjustable according to casting size); for large castings, the automated sand filling and compaction system ensures uniform sand density, solving the problem of low efficiency of manual sand filling for large molds.

• The line is compatible with a variety of dry sands (silica sand, chromite sand, olivine sand) and has no strict requirements for sand particle size (0.15~0.85mm is optional), which can use low-cost ordinary silica sand for most castings, reducing raw material costs.
• No sand mixing equipment is needed (no binder, curing agent purchase), and the only consumable is the plastic film—its cost is far lower than the binder and water treatment cost of traditional green sand molding.

• Castings have smooth surfaces and accurate dimensions, so the post-processing workload (grinding, polishing, machining) is reduced by 30%~60% compared with green sand molding castings.
• The dry sand mold is brittle and easy to break after pouring and cooling. The line’s automated mold breaking station can quickly separate the sand from the casting by vibration and negative pressure release, avoiding the need for manual sand cleaning and improving the efficiency of casting cleaning.

• Vacuum molding lines can be customized according to production needs, supporting the molding of small precision castings (a few hundred grams) to large heavy castings (tens of tons). Small lines are suitable for batch production of small parts, while large gantry-type vacuum lines can process large mold sets (e.g., mold size >5m*3m).
• The line’s modular design allows quick switching of molds for different castings, with short mold change time (1~2 hours for small molds), meeting the production demand of multi-variety and medium-batch castings.

• The vacuum negative pressure (0.04~0.07MPa) applied to the mold cavity and sand box forms a stable "airtight sand mold structure", which has sufficient compressive and bending strength to resist the impact of molten metal during pouring and avoid mold collapse, sand washing or porosity defects.
• The dry sand has good thermal conductivity, which accelerates the cooling and solidification of castings, reduces the formation of shrinkage cavity and shrinkage porosity, and the overall defect rate of castings is controlled at below 5% (far lower than traditional molding processes).