This article aims to provide a clear understanding of shear temperature within an extruder barrel, as well as the various factors that can influence it.
What is it and why does it happen?
In the process of polymer melting during extrusion, it is essential to exercise precise control over temperature and shear forces by adhering to the recommended print speeds provided by both the material and equipment manufacturers. Maintaining optimal temperatures throughout the various sections of the barrel is crucial, as this enables effective melting while preventing polymer decomposition. Excessive temperatures can lead to polymer degradation, whereas cooler areas may result in inconsistent melting. Melting occurs as a result of shear forces generated by the polymer's interaction with itself during screw rotation; this action also produces heat through friction. The movement of the screw exerts shear on the material, facilitating molecular breakdown. However, if shear is excessively applied, it can undermine the material's properties by damaging its molecular structure.
What to do about it?
Accuracy in adjusting print speeds is critical for optimizing the plastic printing process. By modifying the process speeds, one can influence the rate at which material traverses the extruder, which in turn affects both output levels and the shear forces applied to the plastic. An increased screw rotation rate enhances shear, thereby improving melting efficiency. However, it is vital to be mindful of the potential risks associated with excessive shear, elevated barrel temperatures, and prolonged material exposure, as these factors can contribute to the degradation of the material. Careful attention must be given to prevent the overheating or compromising of heat-sensitive polymers. Following the specified material guidelines regarding barrel temperatures and print speeds is essential for minimizing the risks of material failure, product loss, and potential equipment damage.
Prior to utilizing any new materials, it is imperative to thoroughly familiarize yourself with their specifications. Neglecting to do so may lead to costly repairs for the dryer/transport system and the extruder screw assembly.