In general, if there is no unscheduled downtime, the maximum output of an aluminum extrusion profile
depends mainly on the extrusion speed, which is affected by four factors, three of which are fixed and one of which is variable.
One is the extrusion pressure of the extruder, extrusion pressure can be in the ingot temperature is low when the smooth extrusion;
The second is the mold design, extrusion between the metal and the mold wall friction can generally make the aluminum alloy through the temperature rise 35~62℃;
Third, the characteristics of extrusion alloy, is an uncontrollable factor limiting the extrusion speed, aluminum extrusion profile outlet temperature generally can not exceed 540℃. Otherwise, the surface quality of the material decreases, the mold marks are obviously aggravated, and aluminum, dents, microcracks, cracks and other phenomena appear.
The final factor is temperature and degree of control. If the aluminum extrusion profile extrusion pressure is not large enough, it is difficult to extrusion smoothly, or even plug phenomenon, it can improve the ingot temperature, but the extrusion speed should be low, to prevent the material outlet temperature is too high.
Each alloy has its specific optimum extrusion temperature. Production practice has proved that the ingot temperature should be maintained at about 430℃ (extrusion speed ≥16 mm/s). The die temperature of 6063 alloy profile shall not exceed 500℃. The maximum exit temperature of alloy 6005 is 512℃, and the maximum exit temperature of alloy 6061 shall not exceed 525℃. Little change in mold temperature will also affect the output and quality of the product.
The temperature of the extruded cylinder is also very important, especially the temperature rise in the preheating stage to avoid excessive thermal stress between layers. Extrusion cylinder and bushing rise to the working temperature at the same time, the preheating rate shall not exceed 38℃/h. The best preheating specification is to rise to 235℃, hold for 8h, continue to rise to 430℃, hold for 4h before starting work. This can not only ensure the internal and external temperature uniform, but also have enough time to eliminate the internal thermal stress, of course, in the furnace heating extrusion cylinder is the best way to preheat.