Excessive interchangeability error will manifest in obvious symptoms, ranging from process settings to finished product appearance. These can be identified as follows:
1. Typical symptoms of excessive temperature sensor error:
Actual temperature lower than displayed value (negative deviation):** The temperature control displays the set temperature, but the actual melt flow is poor. The injection pressure is higher than normal, frequent short shots and material shortages occur, and weld lines are clearly visible. Increasing the injection pressure easily leads to flash.
Actual temperature higher than displayed value (positive deviation):** An abnormal burnt smell is detected during production. Silver streaks, discoloration, and blackening appear on the surface of the plastic parts. When processing high-temperature materials such as PEEK and fluoroplastics, melt decomposition and bubbling may even occur, and seals may corrode and leak prematurely.
During mass production, the dimensional deviation of plastic parts from different cavities in the same mold is >0.02mm, with irregular fluctuations.
2. Typical Symptoms of Excessive Pressure Sensor Error:
Negative Error (Detected Pressure Lower Than Actual): Automatic pressure compensation by the injection molding machine leads to excessive injection pressure, resulting in excessive flash on the finished product. In severe cases, it can cause the hot runner parting surface to expand, resulting in persistent overflow.
Positive Error (Detected Pressure Higher Than Actual): Injection pressure is limited by the system, leading to frequent material shortages in thin-walled areas. Increasing the holding pressure cannot improve the situation.
Zero-Point Deviation: When the machine is started without pressure, the sensor reading deviates from zero by more than 5%, and the zero point is different each time the machine is started.
3. Common Symptoms: Molding is stable before sensor replacement, but the above problems appear immediately after replacement; the symptoms disappear after reverting to the original sensor. This generally confirms that the problem is caused by excessive interchangeability error.
