Real-time feedback control is a method that links a checkweigher with product filling controls, enabling instant correction of filling errors. It addresses the problem of filler drift, which is caused by changes in the environment, product characteristics or a problem with the filling equipment. When a variation in product weights is detected, the system sends a signal to the filling equipment telling it to adjust fill levels.
METTLER TOLEDO feedback control calculates a mean weight value for a pre-set number of weighings during a given period. This mean weight is then compared against the target weight determined by the manufacturer. A mismatch between the two triggers the sending of an adjustment signal to the filling equipment. The calculation of mean weight, along with the subsequent comparison and feedback control signal is performed as a continuous process. This ensures that any drift is detected early enough to keep it from becoming a serious issue.
Once an adjustment has been made, the checkweigher continues to monitor the weight in the same manner as before, but there will be a delay before the system can send another control signal to the filler again. This gives the filler time to adjust to the new setting and prevents the system from overcorrecting.
Implementing feedback control is straightforward. Checkweighers can be either directly integrated into the filler control, or if the factory floor already includes a networked automation system, they can be connected to that instead. In order to make the feedback control effective, the checkweigher should be as close as possible to the filler to reduce the delay between an adjustment being made and the new setting taking effect. Properly positioned, a checkweigher with feedback control capabilities ensures that overfilling is minimized resulting in cost savings. Under-filling is also avoided ensuring compliance with weights and measures guidelines.