The design principle of the extruder is low temperature extrusion. Calculate economic expenditure: generating heat molten materials require cost, and removing heat cooling raw materials also cost. So the best situation is to provide only the amount of calories under the limit, and excess heat is wasteful. Another reason is that the cooling system efficiency is sufficient, and heat redundancy is a non-small burden, limiting production and quality of the product. The amount of extrudate is low, and under conditions of cooling efficiency, it means that the production can be high, and economic benefits can be improved. The premise of low temperature squeeze out is of course a temperature and high enough to protect product quality and equipment safety.
The cause of excessive melt temperature can be divided into two categories: equipment process and time accumulation. The reason for the equipment process causes high solution temperature, such as unreasonable temperature setting or screw design. All polymers extruded have a minimum extrusion temperature. If the speed of the barrel is too low, the shear thermopsis brought by the screw rotation is bound to raise the temperature of the raw material to the minimum temperature. This situation is out of control, from the process angle, also requires adjustment of process temperature to compliance with extrusion temperature requirements.
The screw design of the blower machine cannot meet the requirements of process conditions, such as raw materials, die pressure and yields, are also very common. This needs to be replaced, a more suitable screw makes the extrusion temperature reduce, and the extrusion production is improved. A deeper measuring segment screw groove can usually reduce shear heat and increase production. This is established in the case where the pressure reflow is not large, so it is usually necessary to configure the slotting barrel at the same time.
If it is a high melt temperature caused by time accumulation, most of the reasons are blocked or screw wear. With the accumulation of impurities on the filter, the hinders of the change melt have increased, which is equivalent to the increase in the back pressure of the die. Thereby, the extrusion production is lowered, and the melt residence time in the extruder is extended. The raw material retention results in absorbing more heat and increases temperature. Replace the filter at this time. If the change network is going to shut down longer, you can consider a multi-station or continuous replacement network.
In addition to the screen blockage, the screw wear is also a reason that causes the melt temperature too high. The screw resistance results in an increase in the top of the screw edge and the inner wall gap, and the extrusion is lowered. This is because the gap is increased, and the pumping machine of the screw can drop. At the same time, the solid bed and the screw inner wall were gently mild, and the melt efficiency decreased caused the extrusion. As the gap is getting bigger, it is necessary to maintain the original extrusion needs to increase the screw speed. This is a longer period of cycle. As a result, the raw material was larger with a larger shear to obtain the same yield as the original, and the melt temperature was raised. So regularly record various boot data, including yield and screw speed. It is also important to measure the wear situation of each position of the screw barrel. If the operator is more than the screw wear mechanism, the measurement does not have to be too frequent.
Raw material replacement is also another reason that leads to rising melt temperature. Raw material type or formulation ratio replacement, even some tiny changes, will affect the rheological behavior of the internal raw materials in the extruder. Because the generation of shear heat and pressure caused by these changes will increase the temperature of the melt.
Finally, the reason for the high melt temperature can be only the wrong temperature setting. Occasionally, after an operator sets a good temperature, it will reset the temperature again. After a while, the temperature setting curve is completely variable, and the cooperation of the screw barrel and the material capacity of the screw barrel is not adapted. This is why we have to fill in the work log. There is a record to form a valid operation that can be performed regularly.
Shanghai Duxia Industry and Trade Co., Ltd. is an enterprise focusing on manufacturing plastic packaging machinery.The main products of Shanghai Duxia Industry and Trade Co., Ltd .: film blowing machine,stretch film blowing machine, printing machine, plastic bag making machine, plastic recycling machine.If you need any of the above machines, please leave your information. Our sales will contact you as soon as possible.
