|Injection and extrusion blow moulding are similar to standard injection and extrusion and many of the actions listed for injection moulding and extrusion should be carried out.
All-electric machines are now available for both injection and extrusion blow moulding. These have all the benefits of all-electric injection moulding machines and can reduce energy use significantly.
Shear heating in blow moulding does not contribute greatly to the heat input to the melt and barrel insulation can be very profitable for both injection and extrusion blow moulding.
Cooling is a major part of the cycle time for both types of blow moulding and a major energy use (at the chillers). Minimising the melt temperature to the minimum needed will reduce the cooling demand and will improve both cycle times and energy use.
Good parison control in extrusion blow moulding will improve product quality, process efficiency and reduce energy use. Investment in improved parison control will have a good payback.
The blowing step is a large user of compressed air in both injection and extrusion blow moulding and good compressed air management is vital, particularly for injection blow moulding of PET pre-forms where the compressed air pressure is generally much higher (40 bar).
Actions to take are:
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