Disruptions to the Operation of HR Moulds and Typical Moulding Defects

Disruptions to the Operation of HR Moulds and Typical Moulding Defects 

It is a lot easier to identify disruptions to the operation of an HR monld system which occur directly, than it is to establish the real causes of moulding defects associated with them. Many of the canses of disrnptions lie outside the HR system, and some occur independently of the nse of an HR system. The most important disrnptions are discnssed in this chapter, together with possible canses and remedies. 

Seal failure in an HR system and leakage of melt most frequently occur when the pressure in the system exceeds the clamping force of the system components in the mould. The first signal that a melt leak has occurred is very slow heating of the manifold. Table 11.1 shows some of the causes and remedies of leakage. 

Central spacer pad dented into monld plate Renew. Reduce cylinder holding force. 

Spacer pads too low Renew or lower manifold housing. 

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