Brown or silver streaks burn

Inadequate packing of melt in cavity Increase shot capacity. Increase holding time Increase injection rate. Check screw non-return valve. 

Inadequate pressure in cavity Increase injection pressure. Increase holding pressure, have it act for a longer time (weight check). 

Incorrect melt temperature Reduce melt temperature (injection machine cylinder, HR), if sinks are at gate or thick wall. Raise melt temperature (cylinder, HR) if sinks are away from gate or at thin wall. 

Premature gate closure Check (shut-off) nozzle closure time. 

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