Rotational sintering technique – Closed moulds are filled with polyethylene powder. With a large heat input, the powder is melted. The mould, which is also called the tool, rotates around two axes and the liquid plastic is evenly distributed on the inner side of the tool, which defines the product shape. After the cooling phase, the tool is opened and the hollow mould may be removed. It is then further processed (sawing, milling, etc.) to obtain a specific end product. It is possible to produce thin, resistant and durable products, or less durable, but cheaper moulds using the same tool. Forming of the product requires a lot of time a high energy input. For GreenLife products, we use modern energy-efficient machines.
Extrusion moulding by blowing is a method of producing hollow mould, which is used for GreenLife products, such as rainwater tanks and polyethylene barrels. Plastic material melted in the moulding machine is formed into a hose. The hose is arranged in the form suitable for blowing with compressed air, allowing the material to reach the inner edges of the mould. The product moulded in this way, after cooling outside the machine, is subject to further treatment.
Special polyethylene suitable for blow extrusion is particularly flexible, has a high resistance to cracking and is designed specially for durable products.
Moulding by spraying is another technique of forming plastics. Polyethylene is condensed at a temperature higher than 200°C in an injection casting machine. Liquid polyethylene is injected under pressure into the spraying tool. Inside the tool, polyethylene is converted back to the solid state by cooling. After opening the tool, the moulded part is removed by a handling device (robot) and it may be subject to further processing or it may be treated as a part ready for use.
The empty space in the tool forms the shape and surface structure of the finished moulded product.