What is form fill seal packaging?

Form-fill-seal machines are machines that form the package, fill it with a wet or dry product and seal it closed.
FFS machines might fill the package from the top or the side.
Most FFS systems use flexible film to form the primary package, such as a bag or pouch. But gable-top and aseptic cartons are also created in a form-fill-seal operation.
The final step can include a 3- or 4-sided seal. For many years, heat sealing has been the preferred method to perform the crucial final step.