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Powder filling systems : film unwind

How does a film unwinder work ?

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Section summary
1. Introduction
2. Film unwinding

1. Introduction

What is a film unwinder ?

The packaging material used in bulk powder filling operation with VFFS or HFFS fillers is delivered in rolls (or reels), that usually make several hundred meters. In order to be able to use this film, it must be unrolled. It is the operation done in the film unwinding section (or unwinder) of a form, film and seal filling machine.

The unwinding has also as a function to ensure a proper tension of the film so that it can be used to form a proper bag.

2. Film unwinding

2.1 Film unwinding components

A filling machine is made of the following sections :

  • Film rollstock
  • (Power unwind)
  • Film tension / dancer
  • (Printing)

Filling machine Film unwinding

Figure 1 : Components of a film unwinding section of a bulk powder filling machine (form fill seal)

2.2 Film unwinding principle of operation

STEP 1 : Rollstock handling

The packaging material, delivered in rollstocks, has 1st to be mounted on a shaft at the back of the machine. It allows to rotate it automatically when the machine is pulling the film to use it.

In some machines, the pulling of the film is not enough and a powered wheel is added to help rotate the rollstock, especially if is very heavy.

STEP 2 : Tensionning

The film must have the right tension to be used further down the process. To enable this, a tensioning arm is pushing on the film and the film is tensioned further thanks to dancers (rollers).

STEP 3 : Printing

An ink or laser printing machine can be added once the film is well tensioned in order, for example, to print a code on the packaging material.


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