Threaded rod, also called bolts or fully threaded rods, are long, straight metal rods that have threads throughout their entire length.



When the threaded rod rotates, the plastic will produce friction and mutual movement against the inner wall of the barrel, the bottom surface of the threaded rod groove, the advancing surface of the screw ridges, and between the plastics. The forward advancement of the plastic is the result of this combination of movements, and the heat generated by friction is also absorbed to increase the temperature of the plastic and melt the plastic. The structure of the threaded rod will directly affect the extent of these effects.

At the same time, the rotation of the threaded rod causes the molten film between the solid bed and the inner wall of the barrel to produce a shearing effect, thereby melting the solid at the interface between the molten film and the solid bed. As the solid bed moves forward in a spiral shape, the volume of the solid bed gradually decreases, while the volume of the molten pool gradually increases.

If the speed at which the solid bed thickness decreases is lower than the speed at which the screw groove depth becomes shallower, the solid bed may partially or completely block the screw groove, causing fluctuations in plasticization or local pressure. Due to the great differences in the melting speed, melt viscosity, melting temperature range, sensitivity of viscosity to temperature and shear rate, corrosiveness of high-temperature decomposition gas, and friction coefficient between plastic particles of various plastics, ordinary general-purpose threaded rods in the usual sense will have a certain section of shear heat excessive when processing certain plastics with prominent melt characteristics. This phenomenon can generally be eliminated by reducing the speed of the threaded rod, but this is bound to affect production efficiency.

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