What are the main reasons for the error of the silicone hose?

What are the main reasons for the error of the silicone hose?

The main factors affecting the error of silicone tubes are subjective factors and objective factors. But mainly subjective factors occupy the most.

The influence of three factors, such as the temperature of the machine head, the melting point and fluidity of the extruded material, different screw speeds and traction speeds, will be explained in detail below.

The first case: due to the influence of the nose temperature. Under the same extrusion conditions, if the temperature of the machine head is too low, the inner diameter of the extruded silicone sleeve becomes larger, and the wall thickness of the silicone hose becomes thinner; when the extrusion temperature is higher, the inner diameter of the silicone hose becomes smaller, then The wall thickness of the silicone hose becomes thicker.

The second case: due to the influence of the melting point and fluidity of the extruded material. The fluidity of the material is closely related to the temperature. As the temperature increases, the apparent viscosity of the material decreases and the fluidity is good. When the temperature of the machine head is lowered, the apparent viscosity of the material is higher and the fluidity is poor, and the forced extrusion increases the pressure of the machine head the tube embryo released from the mold undergoes elastic recovery due to the release of stress, and its expansion level is also proportional to the previous pressure, and at the same time the poor fluidity of the material makes the material extrude less, resulting in a larger inner diameter of the silicone hose and a thinner wall thickness. With the temperature gradually as the temperature rises, the flow performance of the extruded material in the machine head is improved, the pressure of the machine head is reduced accordingly, and the molded tube billet also elastically rebounds due to stress.The compound volume decreases accordingly, and the inner diameter of the extrusion decreases; on the other hand, the extrusion volume of the material increases with the improvement of the flow performance, so that the silicone hose tube wall thickening.

The third case: the effect of different screw speed and pulling speed. At the same temperature, the diameter and wall thickness of the extruded silicone sleeve have a great relationship with the screw speed and traction speed as the extrusion speed increases, the inner diameter of the silicone sleeve will become larger and the tube wall will become thinner. The lower the temperature of the die, the more obvious this change will be.Significantly. This is mainly because as the extrusion speed increases, although the viscosity of the material decreases with the increase of shear stress (shear strength),

However, due to the high processing pressure of the silicone melt, its viscosity also increases with the increase of the extrusion pressure.