Fluoropolymer Processing Aid Dosing Economics under High Shear Profile Tooling
Optimize fluoropolymer dosing between 400 and 800 ppm to balance wall slip against startup induction scrap and avoid masterbatch working capital drag.
Die Land Geometry
Meaning
Mechanical design specifications determine the length and gap width of the final channel through which a polymer melt passes before exiting a machine. Precise die land geometry ensures that the material achieves a uniform velocity profile and sheds its elastic memory. This section of the tool acts as the final shaping zone for the product.
Pressure Regulation
Resistance to flow increases as the length of the parallel section grows relative to its height. Proper die land geometry creates the necessary backpressure to ensure the melt is fully compacted.
Surface Finish
Smoothing the exit path reduces the likelihood of melt fracture or sharkskin defects on the product exterior. When die land geometry is too short, the polymer does not have enough time to relax before it hits the open air. This lack of relaxation causes uneven swelling and a matte or rough appearance.
Dimensional Control
Finished part accuracy depends on the stability of the melt as it leaves the metal surfaces. Refined die land geometry allows for predictable die swell, which is the expansion of the polymer after the squeezing force is removed. Operators measure these results during a pilot run to determine if the metal requires further machining or polishing to reach the desired tolerance.