The main factors affecting the silicone casing tolerance size ?
The first case: due to the effect of die temperature.
Under the same extrusion conditions, if the die temperature is too low, then extruded silicone casing diameter becomes larger, then the silica gel hose wall thinning ; when the extrusion temperature is high, the silica gel hose diameter becomes smaller, then the silicone tube wall thickness of variable thickness.
Second kinds of situations: due to the effect of high and low melting point and fluidity of the extruded material.
The flow properties and temperature of the material has a close relationship with the increase of temperature, the material the apparent viscosity and flow performance. When the die temperature is reduced, the apparent viscosity of flowing material is high, poor performance, forced extrusion makes the head pressure increase, from the tube embryos die due to relieve stress and produce elastic recovery, the degree of expansion and also the pressure before is proportional to, at the same time the flow properties of the material to make the material extrusion less poor, resulting in the silica gel hose diameter becomes larger, the wall thickness thinning. As the temperature gradually increased, the extrusion flow properties of materials can be improved in the die, die pressure decreases, die tube blank because of stress elastic recovery reduced accordingly, extrusion of decreasing of the diameter of ; on the other hand, the extrusion flow quantity with improved performance and increased, so that the silica gel hose pipe wall thickening.
Third cases: the effects of different screw rotation speed and traction speed.
At the same temperature, silica gel tube extrusion of the diameter and wall thickness dimensions and screw speed and traction speed have great relations. Silicone casing with increasing extrusion velocity, its diameter becomes larger, the pipe wall thinning, die temperature is lower, the change is more obvious. This is mainly because with the extrusion speed increase, although the material viscosity with shear stress (shear strength) increases with decreasing, but because the silica melt processing of high pressure, accompanied by an increase in the extrusion pressure, the viscosity is increased, then the flow properties of the material depends largely on the size of the outside heating temperature.
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