|Gas use data
Rotational moulding is the one plastics processing method where gas use is higher than electricity use. It is possible to create a Performance Characteristic Line (PCL) for both electricity and gas use for rotational moulding and these can be combined to give a total PCL for the site. Gas meters do not normally provide interval data but it is possible to fit an interval data meter to the main gas feed. This is strongly recommended for rotational moulding sites. The energy efficiency of individual ovens can be examined by fitting standard or interval gas meters to ovens.
Gas burner efficiency is a key driver of efficiency in rotational moulding and all burners should be monitored to give complete combustion of the gas. Combustion efficiency can be improved by a variety of methods and these should be investigated.
The rotational moulding process does not need a hot mould, it needs a hot plastic that will flow and the quicker the heat can be got into (and out of) the mould the faster the process and the better the process efficiency. Increasing the heat flow can be achieved by:
Reducing the thermal mass of the mould by using high heat transfer rate materials.
Using heat pipes and other techniques to get heat into the mould quicker.
Rotational moulding ovens are often poorly sealed and insulated and seals and insulation will always degrade with time. Examination of ovens with a thermal camera will quickly reveal degraded seals and areas of heat leakage through poor insulation.
Process settings for rotational moulding are often poorly defined and offer good opportunities for improvement.
Actions to take are:
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