Feedthroat Temperature Differences…

I received this question the other day from an experienced molder…

We have 2 different brands of machines. On one brand, the feedthroat temperature is 85-90ºF, yet the other brand has a temperature of 150-190ºF. Is this difference OK…? and could you comment on what effects the higher temperature will have on the process?
My Response
Regarding the Machine Differences – In reality, there is no standard convention for feedthroat temperature measurement. Some machines place the transducer near the cooling lines, some place them closer to the rear heater bands. Additionally, some machines will measure the temperature of the water passing through the feedthroat. In your case, the best way to compare the effectiveness of the feedthroat cooling is to use a surface temperature probe to measure the water temperature entering and leaving the feedthroat on both brands of machines.
Regarding the Effects of Temperature – The feedthroat temperature should low enough to prevent the bridging of material. Always ensure the feedthroat does not get cold enough to induce condensation within the feedthroat.
Additional Thoughts
When such a discrepancy exists between two different brands, it is typically caused by differences in design.

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