Understanding Rollstock: The Foundation of Modern Packaging Processes - Packaging Deep Dive #1

The term "Rollstock" refers to industrially printed packaging films that are supplied on a roll, i.e. a core. What at first glance looks like a simple material is, in fact, the technical heart of modern packaging processes. This is because it forms the basis of all automated bag production.

Rollstock usually consists of multi-layer composite films that are precisely tailored to the requirements of filling machines. These films play a central role – both for brands wishing to package their products and for contract fillers who process roll stock in high volumes on a daily basis.

The term "Rollstock" describes not only the form of delivery but also the function: it refers to a printed film web on a roll that is only transformed into the finished packaging within the machine. This is made possible by so-called form-fill-seal (FFS) machines – often known in German-speaking countries as tubular bag machines.

The principle behind this is as efficient as it is technically precise:

The film web is unwound from the roll, formed into a tube by a forming shoulder, filled and then sealed – usually using heat or ultrasound. In just a few seconds, a flat web is transformed into a finished bag.

Three main packaging formats are produced from Rollstock:

Flowpacks: traditional tubular pouches, such as those used for bars or confectionery

Flat Pouches: Three-sided sealed bags for portions or samples

Stand-up pouches: flexible pouches with a base, e.g. for coffee, powder or snacks

Where Rollstock is used – and why it makes sense there

Now that we have clarified what is technically meant by roll stock, it is worth taking a look at how it is used in practice. After all, its significance only really becomes clear once you understand where it is used – and why specifically there.

Rollstock is used wherever packaging is produced automatically rather than manually. Where individual packaging units are formed, filled and sealed at high speed from a continuous web.

Typical examples can be found in confectionery and food production. Muesli bars, chocolate products or sweets are usually processed on horizontal form-fill-seal machines. The film runs continuously through the machine, is formed, the product is inserted and then sealed. Roll stock enables a constant supply of material here, without interruption.

Rollstock is also the standard solution for powder and dry goods production. Spices, baking ingredients or food supplements are frequently filled on vertical machines. The product ‘falls’ from above into the formed tube. Precise sealing is crucial here, particularly with fine or dusty products. The roll stock used must run smoothly through the machine and also fulfil product-specific barrier properties.

Another classic area of application is small-scale and portion-sized packaging. Sugar sticks, sachets and sample packs are produced almost exclusively from roll stock. Especially with small formats, the efficient use of the film width plays a key role – both technically and economically.

And then there is coffee. Hardly any other product is processed so consistently from roll stock. The combination of high production volumes, sensitive ingredients and clearly defined packaging formats makes roll stock the logical choice here.

And this is precisely where it becomes clear: it is not only the product that determines the design of the Rollstock – but above all the machine on which it is processed. That is why, in the next section, we will look at the difference between horizontal and vertical filling lines – and why this decision has a direct influence on roll width, repeat pattern and sealing.

Technical Overview: Horizontal vs. Vertical Filling

It becomes clear, at the very latest during the technical design of Rollstock, that the product alone does not determine what the film must look like. The decisive factor is, above all, the filling machine on which it is processed.

A basic distinction is made between two types of machine: horizontal form-fill-seal (HFFS) machines and vertical form-fill-seal (VFFS) machines. Both operate on the same basic principle – forming, filling, sealing – but differ in the way the product is fed into the packaging.

In horizontal packaging machines (HFFS), the product is usually inserted into the formed film web from the side. The film runs horizontally through the machine. This method is frequently used for solid products such as bars, biscuits or non-food items. The web is formed into a tube, the product is inserted, and the machine then performs the longitudinal and cross-sealing.

In vertical form-fill-seal (VFFS) machines, on the other hand, the film runs vertically downwards. It is formed into a tube by a forming shoulder, whilst the product is filled in from above – usually by gravity. Typical applications include bulk goods, powders, coffee or small granules.

Both systems are technically mature and efficient. However, when it comes to producing Rollstock, the choice of equipment makes a decisive difference. This is because the machine is, in a sense, the technical bottleneck in the entire process. It defines the parameters within which the material, format and print layout must operate.

These include, amongst other things:

• The maximum and minimum roll width (that can be processed)
• The permissible outer diameter of the roll
• The width and design of the sealing jaws
• The possible capacity in running metres per roll
• The roll core diameter
• As well as the precise web guidance over the mould shoulder

These parameters are non-negotiable – they are determined by the design. If the roll material is not precisely tailored to these specifications, this can lead to problems in the production process.