Board for folding cartons: choosing the right solid board

Virgin-fibre and recycled board

Virgin-fibre board often offers a bright, uniform surface and high stiffness at a comparatively low grammage. Recycled board uses secondary fibres and, depending on the grade, can have different reverse-side colours and surface properties. Both groups include numerous grades for different requirements.

The material designation alone is therefore not enough. Samples, technical data and a test under real process conditions provide greater confidence.

Key selection criteria

Several properties are assessed together for a folding carton suitable for series production:

• Grammage, thickness and bending stiffness
• Creasing, folding and gluing behaviour
• Surface and suitability for offset printing
• Material grain direction
• Humidity, temperature and logistics conditions
• Requirements of the filling process and packaging machine

Develop material and structural design together

A higher grammage is not automatically the better solution. Geometry, grain direction and creasing can also influence stability. HvC therefore coordinates the board grade with structural design, print design, finishing and converting, and can produce a sample for practical testing on request.

For sensitive applications, the necessary material documentation and product-specific requirements are considered during the initial project clarification.

Choose a suitable structure and closure

Folding cartons can be designed with tuck-in, automatic or glued closures, tuck flaps, viewing windows and integrated fixing features, among other options. The structure must suit the product, desired opening, packaging process and intended reuse.

Instead of selecting a structure solely by its name, its interaction with the material and manufacturing process should be tested using a sample. This turns a general folding-carton format into packaging suitable for series production.

Treat grammage as one part of the specification

Grammage describes the mass of board per unit area. On its own, it does not state the material’s thickness or how the finished carton will behave during erection or under load. Two proposed materials should therefore be compared using their technical data and the same structure and product.

The intended use is what matters: a heavy product, frequent opening or processing on a particular line create different requirements. Describe this use rather than specifying the highest possible grammage in advance.

Confirm the material choice with a sample

Check product fit, removal, folding behaviour and closure using a suitable sample. Assess the intended print design on the specified board; a different surface can change its appearance. For automated packing, a trial on the intended customer line is also useful.

Keep a clear record of the selected board grade, the associated structure and agreed approvals. If the material or intended use changes later, suitability should be reconsidered. HvC coordinates material and converting for each project; a board grade alone does not establish a general load capacity.