The malfunction of the quantitative packaging scale not clamping the bag is manifested by touching the bag clamping switch without any action of the bag clamping mechanism. There may be several possible reasons for this malfunction, as the process from touching the bag clamp switch to executing the action of the bag clamp mechanism requires the following steps:

Pneumatic type:

Touch the bag clamp switch - the bag clamp switch signal is sent to the control instrument - the instrument sends a bag clamp action signal - the bag clamp action signal is sent to the external control circuit - the external control circuit controls the bag clamp solenoid valve - the solenoid valve drives the bag clamp cylinder to move.

Electric type:

Touch the bag clamp switch - the bag clamp switch signal is sent to the control instrument - the instrument sends a bag clamp action signal - the bag clamp action signal is sent to the stepper motor driver - the stepper motor driver drives the bag clamp stepper motor to operate.

Once we understand the workflow above, we can use the exclusion method and the method of following the rules to conduct valuation investigation.

Under normal circumstances, when we touch the bag clamp switch, there will be a bag clamp indicator light on the display screen of the weighing instrument. Based on this, we can rule out the cause of the bag clamp input signal: if there is a problem with the bag clamp switch and wires, the controller cannot receive this signal. Conversely, if it can receive it, it eliminates the fault of the input signal.

Then troubleshoot the output fault, for example, we can observe the indicator light on the solenoid valve. If it lights up after touching the bag clamping switch, it indicates that the bag clamping workflow is normal at this point. (Note: In general, even if the solenoid valve is burned out, the indicator light will still turn on and off.)

If it is an electric type, you can observe whether the driver lights up or replace the driver for troubleshooting. In this way, the entire circuit from signal input to output of the bag clamp is basically checked. The last one to be checked is the weighing controller instrument, which is the brain of the entire quantitative packaging scale. If a problem is found with the controller, it will be more troublesome and require maintenance or replacement. However, this situation is usually rare due to the controller's fault.