Meaning
Gradual loss of electrical charge occurs over a period of time. Sensors for cavity pressure experience signal decay when the insulation resistance of the circuit is insufficient to hold the generated charge. This phenomenon causes the measured pressure to appear to drop even if the physical pressure remains constant.
It limits the duration over which an accurate measurement can be sustained during a long injection cycle.
Insulation Loss
Contamination on the sensor connectors is the most common cause of charge leakage. Moisture or oil provides a path for the electricity to escape to the ground. Maintaining a high level of cleanliness in the wiring is the primary way to prevent signal decay.
Measurement Error
False readings occur when the rate of decay is significant compared to the cycle time. The pressure curve will drift downward, leading the controller to believe the packing pressure is falling. This can cause the machine to overpack the part to compensate for the phantom drop.
Environmental Influence
Humidity in the air can enter the cables and degrade the insulation over several days. Sealed connectors are used to protect the sensitive signal from the factory environment. If signal decay is detected, the technician must inspect the entire path from the sensor to the amplifier.
The system must be dry and clean to ensure data integrity.
