Roll stock is film on a roll that your packing machine turns into finished packs. Because the bag is formed on the machine, the film has to match the machine exactly. Before quoting, your supplier and your co-packer will ask for a list of specs. Here is what each one means and why it matters.
Machine type
Vertical form-fill-seal (VFFS) machines pull film down around a forming tube, seal it into a tube and fill it from above: think chips, coffee and powders. Horizontal form-fill-seal (HFFS) machines, including flow wrappers, wrap film around products moving along a conveyor: think bars and candy. The machine type shapes the film structure and print layout.
Web width and repeat length
The web width is the width of the film on the roll, set by your forming tube or machine. The repeat length (or cut-off) is the length of one pack, which is how often your design repeats along the film.
Core size, roll diameter and weight
Rolls are wound on a cardboard core that fits your machine’s unwind shaft; 3-inch (76 mm) and 6-inch (152 mm) inside diameters are the most common. Machines also have a maximum roll diameter and weight they can hold, which sets how much film fits on each roll.
Unwind direction
This tells us which way the printed design comes off the roll and whether the print faces outward or inward. Most suppliers use an eight-position chart; you can see it on our roll stock page. If you are unsure, a photo of a roll mounted on your machine settles it.
Eye marks
An eye mark is a small printed block that a sensor on the machine reads to know where to cut and seal each pack. Its size, colour, position and the contrast with the background all need to suit your sensor.
Material and sealing
- Structure and thickness. The layers of the film and its overall gauge, chosen for barrier and machinability.
- Seal type and temperature. Fin or lap seals on VFFS, and the sealing temperature range your machine runs at.
- Slip. How easily the film slides over the machine’s surfaces, often specified as a coefficient of friction (COF).
Splices and quality
A splice joins two lengths of film within a roll. Many co-packers limit the number of splices per roll and want them clearly marked. Ask about their requirements before you order.
Best practice: run a trial roll on your machine before a full production run, especially on a new structure or a new line.
Your spec checklist
- Machine type and model
- Web width and repeat length
- Core inside diameter, maximum roll diameter or weight
- Unwind direction
- Eye mark size, colour and position
- Product, fill weight and seal type
- Splice requirements
Ready to quote? See our printed roll stock or send us your specs. Need the packing done too? Our sister company offers food co-packing in Vancouver and Toronto.
