A cartoning machine can only run as well as the folding carton it processes. Cartons that are hard to open, too tightly sized or whose flaps don't fit lead to stops and rejects. The good news: with a few clear specifications, this can be avoided when designing the folding carton.
In this article we summarise what we at Kappler look for when we check a customer's carton for our vertical cartoning machines.
The most important rules at a glance
- The folding carton must open easily.
- Creases and fold lines are pre-broken for automatic processing.
- The product is 3–5 mm smaller than the inner dimensions of the carton.
- The grain runs across the carton height.
- The side seam is glued straight.
- The print zone for LOT and date is on the lower main flap (optionally the upper one), 10 mm from the crease.
Dimensions and format range
We describe folding cartons with three dimensions: width (W), depth (D) and height (H). In a vertical cartoning machine, the carton stands upright, so the height is the direction in which the product is inserted from above.
So that the product drops in reliably and the carton closes cleanly, it should be 3 to 5 mm smaller than the inner dimensions. If the clearance is smaller, products jam. If it is larger, the product slides around in the carton and the closure suffers.
| Machine | Format min. (W / D / H) | Format max. (W / D / H) |
|---|---|---|
| KC-V6 | 25 / 18 / 60 mm | 120 / 60 / 180 mm |
| KC-V8, KC-V10 | 25 / 18 / 60 mm | 120 / 90 / 180 mm |
| KC-V8 Large | 60 × 30 × 80 mm | 200 × 100 × 250 mm |
Creases, grain direction and gluing
Pre-broken creases
The machine erects the flat folding carton. This works reliably if creases and fold lines are already pre-broken. The carton must open easily – blanks that are too stiff spring back and disrupt the cycle.
Grain direction
The grain direction of the board should run across the carton height, i.e. over the side panels width – depth – width – depth. This keeps the erected carton dimensionally stable.
Side seam gluing
The longitudinal seam must be glued straight. Cartons glued at an angle do not open at right angles and can get stuck in the carton holder.
Tuck-in flap: cut-outs and flap length
For the tuck-in flap, cut-outs and flap length depend on the width and depth of the folding carton. Our standard layout specifies these values:
| Width W (mm) | Cut-out on the tuck flap (mm) | Slit on the dust flap (mm) |
|---|---|---|
| 15–18 | 4 | 2,5 |
| 19–30 | 5 | 3,0 |
| 31–60 | 6 | 3,5 |
| over 60 | 7 | 4,0 |
| Depth D (mm) | Tuck flap length (mm) | Depth D (mm) | Tuck flap length (mm) |
|---|---|---|---|
| 12–14 | 8 | 27–29 | 13 |
| 15–16 | 9 | 30–33 | 14 |
| 17–19 | 10 | 34–36 | 15 |
| 20–23 | 11 | 37–80 | 16 |
| 24–26 | 12 | 81–100 | 18 |
| over 100 | 20 |
There should be a gap of at least 2 to 2.5 mm between the closure flap and the dust flap. Further dimensions depend on the material thickness – we will gladly send you the complete dimensional drawing.
Hotmelt closure
With the hotmelt closure, the flaps are glued. So that they do not obstruct each other when closing, different flap dimensions apply:
| Flap | Specification |
|---|---|
| A | Depth minus 1 mm |
| B | Width minus at least 3 mm |
| C | one third of the width, at least 15 mm and A minus 3 mm |
| E | A minus 2 mm |
| F | Width minus 8 mm |
At the creases of the closure flaps, 0.5 mm nicks ensure that the flaps fold cleanly.
Print zone for LOT and date
If LOT and expiry date are embossed or printed in the cartoning machine, a free zone is needed. It is on the lower main flap – on request on the upper one – and keeps 10 mm from the crease. Plan this area in the artwork without varnish and without dark areas, so that embossing or print is easily legible.
Leaflets for the leaflet inserter
If a leaflet is to go into the folding carton, these values apply to the automatic inserter:
- folded 20–50 mm wide and 90–210 mm long
- paper from 50 g/m², each layer at least 0.05 mm thick
- at least 8 layers for reliable handling
- closed edge, inserted with the folded side towards the fixed guide
- Code zone at both ends
Checklist before ordering
Before ordering folding cartons in large quantities, it is best to send us:
- the die-cut drawing as PDF or DXF,
- some samples of the folding carton and the product,
- the planned closure type and whether a leaflet is included,
- the annual quantity.
We check the carton against our specifications and tell you which Kappler cartoning machine fits – or what should still be adjusted on the carton.
