The Issue of Uneven Gloss in PVC Extruded Profiles
Release time：2020-07-21
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Formulation Fine-Tuning: Check the lubrication balance (especially external slippage) and ensure proper dispersion (consider adding a dispersant or optimizing the mixing process).
Process Optimization: Fine-tune the temperatures of each section of the extruder (particularly the homogenization section and die head temperature) to ensure uniformity; carefully check and adjust the temperatures of each heating zone in the die head to make them as consistent as possible; Check and stabilize the feed rate; optimize cooling and vacuum to ensure sufficient and uniform vacuum levels across all sections of the forming die (clean the vacuum ports); check and optimize the cooling water flow rate, temperature, and distribution uniformity—ensuring thorough and uniform cooling is key to resolving uneven gloss across the width; adjust the screw speed to match the haul-off speed.
Equipment Maintenance: Thoroughly clean the dies (die head, forming die) and repair any damage; inspect and maintain the temperature control, vacuum, and cooling systems; inspect the screw and barrel for wear.
Die Evaluation: If the above measures are ineffective and the problem is recurring and occurs at specific locations, consider whether the die (runner design, uniformity of die lip clearance, length of the straight section, surface finish) has fundamental design or manufacturing defects.
In summary, resolving the issue of uneven gloss in PVC extruded profiles requires systematic troubleshooting and precise adjustments across three core dimensions: raw material formulation, process parameters (particularly temperature and cooling/vacuum), and equipment condition (especially the die and temperature control system). Uniform die head temperature and uniformity in shaping cooling and vacuum are often the key factors in resolving transverse gloss unevenness.
