Multifunctional rotomoulded products
Air cooling is used to cool parts in a wind turbine. This for example applies to the transformer and electronics. This requires a fan housing in which an electrically driven fan is mounted. This housing also has an air inflow opening and one or more air outflow openings. In addition, the housing must be fitted with an inspection hatch to enable the fan to be mounted and maintained. By means of rotational moulding, all these functions can be integrated into one seamless moulded product with moulded inserts to mount the inspection hatch, outlets where air hoses and air ducts can be mounted and provided with all holes and openings manufactured by robot milling.
Excellent vibration resistance
After many hours of operation, a fan can become unbalanced, for example due to pollution, which causes vibrations. Vibrations are also present in the gondola itself due to all rotating and moving parts and weather influences. Rotationally moulded fan housings are made from extremely tough polyethylene. And because rotational moulding is a pressureless process, there are virtually no internal material stresses. This makes our fan housings highly resistant to vibrations and shocks. Tens of thousands of Rotovia rotationally moulded housings have already been installed in wind turbines and achieved many trouble-free operating hours. Due to the unique combination of integration of functions and the long service life, more and more housings made of sheet steel being replaced by rotationally moulded fan housings.
Rotational moulding: ideal for large products
The basis of the rotational moulding process is that a powdered polymer is placed in the mould in the correct weight. The mould is then slowly rotated on two perpendicular axes and heated simultaneously. At some point, the inside of the mould becomes so hot that the powder melts against the mould wall, so that the wall thickness is built up layer by layer with each rotation. Unlike injection moulding, where the plastic is pressed into a mould under very high pressure, rotational moulding does not involve any pressure. This means that relatively large moulds are constructed with the same thin wall thickness can as small moulds and therefore have a relative low weight. This means that even very large moulds can be made at relatively low cost. Based on these advantages, Rotovia, together with its customer, has made a one-piece large fan housing, combined with a filter housing and air duct with a length of almost two metres.