|Get the right machine
Always check that the machine is right for the job. Large machines making small products are energy inefficient and will increase costs. For some smaller machines the use of accumulators can reduce transient power requirements.
Process setting and controls
Process setting is the key to energy efficiency in injection moulding. Optimised process settings will increase productivity and reduce energy use.
Barrel heating and insulation
Barrel heating in injection moulding machines is a major energy user and the energy use can easily be reduced by fitting barrel insulation. Barrel insulation will reduce energy use in heating with payback periods of around 1 year. Barrel insulation also reduces Health and Safety concerns with hot surfaces. At sites which also use air conditioning, barrel insulation will also reduce the air conditioning energy use.
Even if barrel insulation is not used it is essential that barrel heaters are ‘bedded-in’ and use a conductive metal compound between the heater and the barrel for good heat transfer. Sites should also ensure that barrel heater thermostats are accurate and can control the heater.
Injection moulding machines have made a huge leap in efficiency with the introduction of all-electric machines and these can give processors a permanent advantage over competitors using conventional hydraulic machines. All-electric machines not only use up to 60% less energy in operation but also have lower standing losses, are easier to maintain and are more accurate in operation.
Retro-fitting VSDs to hydraulic machines is very cost effective if the machine parameters are right. VSDs will save energy by slowing down or stopping the hydraulic motor when the cycle does not need it. Investigate if the machines are suitable (large fixed displacement motors, long cycle times and long operating hours).
Mould temperature controllers
Mould temperature controllers (MTCs) are a hidden cost in injection moulding and the need to use them should be examined carefully. Insulate piping between MTCs and tooling to reduce parasitic heat gains or losses.
Initial mould design can affect energy use and designers need to be aware of the cost of their decisions. Areas to look at are:
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