Place the checkweigher after the filler and final packing and before case packing so each individual pack is weighed. The metal detector normally sits before or beside it. A combo unit on one belt saves space, provided the reject system is defined for both.
The position of a checkweigher matters as much as the machine itself. Placed before packing is complete, it does not weigh the true final pack; placed too far from the filler, it reveals filler error late.
A common order on a food packing line is: filler and seal, then (where needed) the metal detector, the checkweigher, followed by labelling, case packing and palletising. The key point is that the checkweigher must weigh what reaches the customer, so it should come after the last step that adds or removes weight (heavy labels, lids, sachets), or that weight must be included in the product tare.
Both orders are used in practice. The main considerations:
For products in metal or foil packaging where a standard metal detector does not work, metal inspection is done before filling and the checkweigher still works after packing; see metal detection for flour and grain for how product type shapes the setup.
The closer the checkweigher is to the filler, the faster the feedback and the fewer packs are wasted if the filler drifts. But the distance must let the pack settle: filler vibration, product movement inside the pack and air drafts must die down before the pack reaches the weigh belt. The exact distance depends on line speed and pack type and is set at the design stage.
Design a collection path for rejected packs for both devices. An underweight pack can be checked or refilled, but a pack contaminated with metal must go to a lockable bin so it cannot return to the line. Common reject mechanisms are a pusher arm, air blast and drop flap; see metal detection for dairy for how different flow patterns change the layout.
Connecting both devices to the PLC allows events to be logged in one place and the filler to be stopped automatically when the mean drifts. That integration also simplifies audits.
The final layout needs the real line. Send us a plan or photo of the line and the pack details and we will propose the position of the checkweigher and metal detector and the reject path.
Share your production line's specs with us and we'll recommend the right model.
Both are possible. Fitting the metal detector first removes contaminated packs sooner and keeps weight data cleaner; the final choice depends on layout and space.
In limited space, one belt with one infeed and outfeed serves both inspections and data is logged in one place.
Far enough for the pack to settle, near enough for fast feedback; the exact figure depends on speed and pack type.
No. A pack contaminated with metal must go in a lockable bin so it cannot re-enter the line, while an underweight pack can be checked or refilled.
