New methods for producing energy savings when using Hot Runner Systems
The benefits offered by hot runner systems for the injection molding industry such as material savings and cycle time reduction are widely known. However, in the past very little attention was paid to the amount of energy required to operate the hot runner equipment. Energy savings have become increasingly more important as electricity costs have increased in recent years.
Hot runner systems are comprised of hot runner nozzles and a manifold for multi cavity applications. The melt conveying channels inside these components are typically heated with 230V heaters. The energy requirement for these heaters depends on the type of resin, nozzle/manifold mass and other factors.
Through the use of new materials and manufacturing methods the energy consumption of hot runner nozzles can be reduced on average by 35%. The energy savings for the nozzles can be significant when higher cavitation molds are produced due to the high number of nozzles installed.
While there is usually only one manifold in a hot runner system the amount of wattage required to heat the manifold block can be quite high due to the size and mass of the steel block. To minimize the heat radiation from the manifold block the hot runner manifold can be completely encased with insulating material. All components of the manifold which are in direct contact with the tool are also made of special insulating materials resulting in further energy reduction.
Besides the pure energy savings the heat distribution of the tool is thus only minimally affected.
Optimizations to the nozzles and manifolds can be made that not only reduce costs by saving energy, but also result in a more stable temperature balance of the entire tool.
Examples of hot runner installations using these methods can show the efficiencies gained. The longer the mold is running in production the larger the savings. These savings will only become more significant in the future as the cost of electricity is expected to rise even further.