ROTOMOULDING PROCESS

Manufacturing Process

The principle of rotational molding of plastics is simple. Basically, the process consists of introducing a known amount of plastic in powder (granular) or form into a hollow, shell-like mold. The mold is rotated and/ or rocked about two principal axes at relatively low speeds as it is heated so that the plastic enclosed in the mold adheres to the mold and forms a monolithic layer against, the mold surface. The mold rotation continues during the cooling phase so that the plastic solidifies. When the plastic is sufficiently rigid, the cooling and mold rotation is stopped to allow the removal of the plastic product from the mold.

PROCESS

Rotational Moulding, also called Roto Casting or Roto Moulding is a unique process because the heating, shaping and cooling process take place inside a mould with no application of pressure. The process is carried out at the ambient pressure, which makes the products withstand environmental stress and crack resistant during use.

A predetermined quantity of blended polyethylene resin powder is placed inside a cold Mould (usually of aluminum or steel sheet metal).
The Mould is then rotated (Bi Axially) and gradually heated inside the oven. As the metal Mould gets heated, the polymer resin powder melts and the molten resin eventually get distributed (Coated) along the inner surface of the Mould. When all the powder has melted & distributed, the Mould is transferred to a cooling chamber keeping the Mould rotating.
The Bi-Axial rotation is continued until the cooling process is finished and the polyethylene has solidified. The Mould is then opened, and the finished product is removed. Given process chart helps understand the system.

RAW MATERIALS

LLDPE / MDPE / HDPE (Roto Moulding Grade)
MFI Between 3.0 to 4.5 and Density
Between 0.92 to 0.95 are widely used.

STEPS FOR CREATING A WORLD CLASS PRODUCT IN ROTOMOULDING

MANUFACTURING OF RAW MATERIAL PROCESS

LLDPE GRANULES ARE CONVERTED INTO POWER PORM

The material (granules) pours to the grinding head or mill to break into dust particles.
After that through the cyclone, remove the larger particles and separate ideal particles for the manufacturing process.
In the grinding process, frictional heat increases the temperature of the metal cutti

LLDPE GRANULES ARE CONVERTED INTO POWER PORM

The material (granules) pours to the grinding head or mill to break into dust particles.
After that through the cyclone, remove the larger particles and separate ideal particles for the manufacturing process.
In the grinding process, frictional heat increases the temperature of the metal cutting faces, the individual polyethylene particles, and the surrounding air. Because of that reason the temperature must be controlled so that it does not rise beyond the melting point of the polyethylene or to a critical softening temperature, prior to melting, when the particles begin to adhere to each other.
This can cause blockages in the passage of new material entering the mill. Other additives, such as UV modifiers, impact modifiers, thermal stabilizers, and antioxidants are mixed during the dry blending process.
After the above processes the material is ready to use for rotational Moulding

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ROTOMOULDING PROCESS

MOLD CHARGING:

After the material process, the material is feed into the rotational Moulding mould.

The amount of ** kg of the processed coloured LLDPE material feed into the mould.

Then the mould is closed and ready to begin the heating process.

Heating

Rotational molding begins with powder and then focuses on powder flow, sinter-melting

MOLD CHARGING:

After the material process, the material is feed into the rotational Moulding mould.

The amount of ** kg of the processed coloured LLDPE material feed into the mould.

Then the mould is closed and ready to begin the heating process.

Heating

Rotational molding begins with powder and then focuses on powder flow, sinter-melting or coalescence, densification, and cooling of the polymer. Heating is most important factor to obtain a good product.

The oven temperature nearly increased to 300℃. The below figure indicates the different temperature variations in the oven

Mould Cooling

Highly powered blower fans are placed under the moulding machine to provide air which required for cooling.

In air cooling the speed and axial rotations of the mould keep as same as mould heating.

Part ejection or demoulding

The ideal time for part removal from the oven is immediately after the polymer is fully dandified into a monolithic liquid film uniformly coating them old surface. At that time the product is removed from the mould.

This is the final process of manufacturing plastic

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ROTOMOULDING PROCESS

Manufacturing Process

PROCESS

RAW MATERIALS

STEPS FOR CREATING A WORLD CLASS PRODUCT IN ROTOMOULDING

MANUFACTURING OF RAW MATERIAL PROCESS

ROTOMOULDING PROCESS

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