Moulding masterclass | processing feature
the best mould cooling channel layout can be compromised on mould installation. Moulding expert John Goff explains why
effective mould cooling means making the right connection
the best efforts of the tool designer in placing the correct number of cooling channels in the mould and to locate the inlet and outlet ports at the optimum positions can so easily be undone when the mould is placed in the machine if appropriate consideration is not paid to how those channels are connected. in the previous instalment we considered how poor
selection and sizing of connectors can restrict the rate of cooling medium flow into the mould’s cooling circuits. in this instalment we will take a detailed look at how those circuits should be connected to achieve the optimum results in terms of part quality and production efficiency. this is an important issue, particularly when it is necessary to achieve the maximum performance from the mould. the two main options available to moulders are the
use of looped circuits or independent circuits. the latter option, where each cooling circuit connects to a distribution manifold or flow regulator, is the most effective. Unfortunately, it is far more common to see looped circuitry used – installations where external loops are fitted to create a single path of coolant that cascades through the mould – and this is even more
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likely in the case of large mould tools weighing in excess of one tonne. there are a number of reasons why looped circuit
connections continue to be so widely used: l ease of mould tool set-up l insufficient time for mould changeovers l lack of available inlet/outlet ports on distribution manifolds
l Shortage of connecting hoses l established practice employed within the moulding division. however, whatever the reason, it must be under-
stood that the effectiveness of heat energy removal from within the mould is greatly impaired, especially as the number of looped circuits increases. Figure 1 highlights a typical set up that often results
in cycle time and moulding quality issues. the mould tool shown has been well designed, providing the ability to effectively remove residual heat energy through the numerous cooling circuits in the mould tool. however, the majority of the individual circuits are looped, which prevents the residual energy from being uniformly and effectively removed.
April 2012 | injection world 53
Above: Careful cooling circuit
connection can pay big benefits in final part quality
s
photo: engel
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