Abstract: This article analyzes the reasons of white and transparent flow lines generated during the film blowing processing, offers solutions to avoid flow line in terms of processing tehcnics and die designing. Optimizing the design of spiral-mandrel-type die head by simulation analysis with rheological theory, to reduce and diminish the flow lines and meet the requirement for higher processing and experimental standards.

Key words: flow line, melt line, hole defect;healing;spiral mandrel channel, relaxation time