V-Process Molding Equipment and Process Flow

V-process molding equipment, also known as vacuum sealed molding, adopts binder-free dry sand for molding. Plastic film is used to seal the mold surface, and a vacuum pump creates a pressure difference between the inside and outside of the mold, compacting the dry sand to form the mold cavity. Molten metal is then poured to obtain high-precision castings.

Due to its high reclaimed sand reuse rate, clean working environment, and high metal utilization, the V-process has been listed in the national Clean Production Technology Catalogue.

The process has been successfully applied in industries such as construction machinery counterweights, petroleum machinery, belt pulleys, bogie side frames, axle housings, brake drums, and high-manganese steel liners, among others.

I. V-Process Molding Process Flow

1. Sand Treatment Section – Main Equipment

The sand treatment section mainly includes the following equipment:

Shakeout dust hood, cross-transfer flat car, shakeout grating and transition sand hopper, vibrating conveying sand screen, slat chain elevator, transition sand silo, sand gate valve, fluidized cooling bed, bucket elevator, suspended magnetic separator, belt conveyor, plow-type discharger, waste handling single-girder crane, dust collection system, electrical control system, pneumatic control system, and water control system.

2. Molding Section – Main Equipment

The molding section mainly includes:

Non-powered return empty box roller conveyor, single-girder crane for empty box handling, rain-type sand filling device, film covering machine, film spreading platform, coating drying device, mobile vibration compaction table, robot manipulator, mold closing transfer car, sand boxes, sand spreading and recovery system, hydraulic mold stripping cylinders, mold turning mechanism, vehicle-mounted vacuum pump, electrical control system, vacuum system, hydraulic system, pneumatic system, and water control system.

3. Molding Process Flow

A. Small, Medium, and Large Sand Boxes

Model (with vacuum chamber) is placed on the vibration compaction table

→ Model positioning

→ Manual application of talcum powder

→ Mobile vibration table transfers pattern plate to film covering station

→ Film covering machine retrieves film, heats it, and covers the model

→ Manual coating application

→ Single-girder crane places empty box from return roller conveyor onto negative-pressure pattern plate

→ Mobile vibration table moves to coating drying station for drying

→ Mobile vibration table moves to sand filling station

→ Vibration table rises into position

→ Rain-type sand filling device opens

→ Vibration compaction

→ Rain-type sand filling device closes

→ Vibration stops

→ Vibration table lowers into position

→ Mobile vibration table moves while bottom box sand scraping device operates to remove excess sand

→ Moves to mold stripping station

→ Manual back film covering

→ Robot performs mold stripping and box turning

→ Bottom box is placed onto mold closing transfer car

→ Manual core setting and top box sand filling with vibration compaction

→ Mobile vibration table moves to stripping station

→ Manual back film covering

→ Manual insertion of vacuum hose

→ Manual removal of sprue and riser rods

→ Robot clamps and strips mold while operator removes vacuum hose

→ Robot moves to mold closing transfer car to complete mold closing and manual locking

→ Mold closing transfer car exits

→ Overhead crane (assisted by vehicle-mounted vacuum pump) lifts sand box to pouring area

→ Vacuum connection and waiting for pouring

B. Extra-Large Sand Boxes

After sand filling and vibration compaction, the mold is directly transferred to the stripping station in front of the robot

→ Manual back film covering

→ Vacuum applied

→ Bottom box is lifted to the box turning machine for turning

→ Transported to pouring area for manual core setting

→ Mold closing and waiting for pouring

Spilled sand is lifted by the recovery system back to the molding sand silo.

If the robot fails, mold stripping and box turning can be completed manually at the station in front of the robot to ensure orderly production.

II. Main Equipment Performance Description

1. Shakeout Dust Hood

During V-process shakeout, sand temperature is high and sand is fine, resulting in heavy dust generation. A semi-enclosed dust hood is installed to reduce dust emission and improve workshop conditions.

2. Shakeout Grating and Hopper

Designed to bear the weight of sand, sand boxes, and castings under elevated temperatures. Constructed using 25# I-beams and 16 mm perforated steel plates; hopper made of 6 mm steel plates reinforced with 5# channel steel and internal tie rods. The grating separates large ferrous impurities and unmelted plastic film.

3. Inertial Vibrating Sand Screen

Suitable for short-distance conveying of molding sand, hot reclaimed sand, crushed stone, and coke. The segmented cover ensures dust sealing and convenient screen replacement.

4. Slat Chain Elevator

A commonly used vertical conveying device in mechanized foundries. It uses slat chains to lift powdery, granular, blocky, and highly abrasive materials, forming flexible conveying systems when combined with other conveyors.

5. Fluidized Cooling Bed

Suitable for cooling reclaimed sand without binders (V-process, lost foam) or with good flowability binders (resin sand, sodium silicate sand). Cooling water flows through the heat exchanger while high-pressure air fluidizes the sand for efficient heat exchange. Cooling water pipelines are pressure-tested to ensure no leakage at 6 kg pressure.

6. Bucket Elevator

Used for vertical conveying of reclaimed sand, waste sand, new sand, and steel shot. Can be integrated into various conveying systems.

7. Belt Conveyor

Improved design suitable for conveying non-corrosive, low-temperature bulk materials such as new sand, reclaimed sand, molding sand, coke, limestone, and materials in grain and chemical industries.

8. Suspended Magnetic Separator

Installed above reclaimed sand conveyors to effectively separate magnetic metal impurities such as iron particles, slag, and mill scale.

9. Non-Powered Return Box Roller Conveyor

Transfers empty sand boxes to molding stations, improving overhead crane utilization. Installed with a slight incline for smooth movement.

10. Film Covering Machine and Film Spreading Platform

The mobile film covering machine is driven by a geared motor and performs film picking, heating, and covering operations. Quartz electric heaters heat the film to a mirror-like state before covering the model under vacuum. This is a key component of the V-process line. The film spreading platform assists automatic film spreading and cutting.

11. Mold Closing Transfer Car

Works with the robot to close molds and transfer them for crane handling. Driven by a hardened gear reducer with variable-frequency control for smooth and precise positioning.

12. Coating Drying Device

Uses hot air curtains to blow heated air onto the model surface, achieving rapid coating drying and improving production efficiency.

13. Mobile Vibration Compaction Table

Suitable for binder-free and free-flowing binder sands. Four vibration motors generate synchronized vibration, compacting sand uniformly through high-frequency, low-amplitude vibration.

14. Rain-Type Sand Filling Device

Composed of fixed frame, movable frame, and cylinders. Sand flows through aligned holes to achieve uniform rain-type filling. Equipped with dust extraction and rubber padding to avoid rigid contact.

15. Robot Manipulator

A key automation device used for mold stripping, turning, transferring, and mold closing operations.

16. V-Process Special Sand Boxes

Conventional sand boxes cannot be used. V-process sand boxes must be sealed on all sides and equipped with internal filtering and vacuum extraction devices.

17. Vehicle-Mounted Vacuum Pump

Uses Roots vacuum pumps mounted on a double-girder crane, eliminating long trailing vacuum hoses and reducing labor intensity.

18. Single-Girder Empty Box Handling Device

Transfers empty sand boxes from the return conveyor to pattern plates, improving crane utilization. Operated via remote control.

19. Cross-Transfer Flat Car

Transfers castings after shakeout to the buffer area. Extended design protects bearings and cables from heat; frame welded from 250 H-beam steel.

20. Hydraulic System

Composed of pump station, valves, cylinders, and pipelines. Features reliable sealing, adjustable speed, cooling devices, and monitoring for oil temperature, pressure, level, blockage alarms, and safety protection.

21. Dust Collection System

Total air volume: 78,000 m³/h. Two-stage dust removal: cyclone separators followed by pulse-jet bag filters. Molding sand hoppers and sand filling points use pulse-jet bag collectors.

22. Electrical Control System

PLC-based control using Siemens PLCs

Manual/automatic operation modes

VFD control for vibration tables, robots, transfer cars, and film covering machines

Soft starters for vacuum pump motors

23. Vacuum System

Composed of water-ring vacuum pumps, vacuum stabilizing tanks, negative pressure dust tanks, pipelines, and electrical control system.

24. Water Control System

Includes centrifugal pumps, pipelines, valves, cooling towers, and water tanks. Supplies cooling water for the fluidized cooling bed, vacuum pumps, and hydraulic coolers.

25. Non-Standard Steel Structures

Includes shakeout dust hoods, gratings and hoppers, pit covers, molding sand silos, platforms, ladders, guardrails, chutes, dust pipelines and supports, film covering machine structures, vibration table rails and supports, vacuum and water pipelines, loose sand gratings and hoppers, and transition sand silos.