Extrusion process optimization to prevent surface melt fracture and shark skin effect
The capabilities of Line Confocal Imaging has been tested extensively at Tampere University of Technology. Juuso Hautala, Faculty of Material Technology, used FocalSpec Line Confocal Sensor LCI 1200 during the experimental part of his Master’s thesis on Development of Extrusion Process.
Experimental part included polymer cast film manufacturing in laboratory environment. An extruder was being used. Line Confocal Sensor LCI 1200 was installed over extruder’s film rolling unit. FocalSpec roughness measurement software was used for data collection and analysis. The software was the same than the one globally used with FocalSpec MicroProfiler MP900 – an online surface roughness measurement system for cables and medical tubes. Two different materials, both widely used in film manufacturing industry, were studied.
Purpose of the study was to examine surface roughness defects, namely sharkskin phenomenon and advanced surface melt fractures. The capabilities of line confocal imaging in industrial use were also discussed.
According to the Master’s thesis, “Polymer cast film was successfully manufactured with different processing parameters and the optical measurement unit was able to determine the surface roughness of polymer film precisely.” Furthermore, “For applications requiring accurate and repeatable surface roughness measurement, line confocal imaging is an highly useful quality control technology.”
Picture 1: LCI1200 can be used for automated surface roughness measurement of flat layers in various industrial settings. The measurement works perfectly well even for transparent and high shiny surfaces such as plastic, glass, film, foil and metal.
Reference: Use of optical measurement unit in development of extrusion process, Juuso Hautala, Tampere University of Technology, Faculty of Material Technology, September 2016. Examiner: Professor Jyrki Vuorinen.