Manifold spacer pads

Sintered ceramics (thermal conductivity below 2 W/mK) for nozzle and manifold spacer pads. 

In the second case, axial elongation of the manifold, nozzle and spacer pads need to be taken into consideration so that when the mould and HR system are heated, the pretension is attained in the set that does not exceed the admissible surface pressure between pad and clamping plate (this is normally the most loaded place in the set). Figure 4.100a shows diagrammatically an HR system installed without a gap. 

Heat conduction from the manifold takes place chiefly via the spacer pads and fastening bolts, and perhaps also via the non-heated sprue bushing. A diminution in heat losses caused by conduction may be attained by ... 

Calculation example. As an example, the power demand is calculated for a manifold (see Figure 4.60) 80 x 500 x 46 in size supported on three spacer pads 025/014 x 5. The manifold is designed to operate at a maximum temperature of 360 °C with a mould temperature of 100 °C. 

Spacer pads too low Renew or lower manifold housing. 

Manifold overheating Check/renew thermocouple Check/repair mould pressure plate and spacer pads (possible denting or deformation). 

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