Folding cartons are one of the most efficient ways to package products. Heiber + Schröder offers highly versatile tray formers to erect a variety of tray style cartons like chip scoops, French fry or nacho trays, Chinese takeaway boxes with web corners, trays with lid, hamburger clamshell boxes and more. Tray walls can be vertical or tapered. H+S tray formers can form trays with a 5° - 40° taper.

Achieving a consistently well-formed package during the production run implies several tasks before the gluing and folding phase, and technological improvements featured on Heiber + Schröder tray formers help you achieve the perfectly finished product.

Tray Design

If we review the folding carton manufacturing process, it all starts with the design itself. The package should be developed in a way that fulfills its four basic functions: information, visual impact, convenience, and protection. The shape and material must be evaluated to deliver structural support. The most widely used paperboard types are SBS (coated solid bleached sulfate), SUS (coated solid unbleached sulfate) and coated recycled. Other substrates are folding box board (FBB) and white lined chip board (WLC). They are coated with clay for optimum printability. Heiber + Schröder tray formers can work with paperboard ranging from 200 to 600 g/m2 and corrugated up to 1.5 mm thick.

The package dimensions affect sheet utilization rate. Cleverly laying out the blanks in the full-size paperboard sheet can save thousands in waste. Not only must the design fit the sheet, but it is restricted by the maximum blank sizes that the tray formers can process.

Cutting and Creasing

Along with the graphic design, the package has a cut and crease pattern. The cutting die extracts the package from the sheet and the creases (also called "scores") mark where the carton will be folded to take three-dimensional shape. Creases define the edges of the panels and flaps. Knowing that all paperboard is manufactured in a process where fibers are aligned in one particular direction, it makes sense to make the creases run in the same direction as these fibers ("with the grain") instead of perpendicularly ("against the grain"). Otherwise, during the forming process, the crease may break.

When designing the folding carton, the format may have glued flaps or locking corners to hold the package in shape for final use. Designers must consider that tray formers require that the glued areas do not have printing on them, for better adherence.

The actual cutting and creasing operation is done with a die, which can be setup in flat bed or rotary equipment. When the latter is used, it is usually as a final stage in the printing line. When the crease is produced, some internal delamination occurs (the different layers in the paperboard separate). And when folded in the tray former, further delamination takes place. If the crease was well done, the printed side should not show cracking, and the reverse side should have an even bulge, without crumpling. If the carton is poorly creased, the liner splits and exposes the inner layers of the paperboard.

An irregular crease has several effects on the package: it can cause the panel or flap to spring back (preventing proper adherence or folding) and reduce package compression strength as the panels and flaps will be incorrectly positioned in the tray former.

Quality control in this first stage is crucial. The edges of the printed pieces should be clean and free of debris, such as torn fibers or clumps. Loose paperboard particles would compromise the efficiency of the gluing process. 

Once the carton blanks are cut and creased, they may be sent to the packager for storage and later product filling, or they may be glued and folded for convenience, using tray formers like the CE1000 or the CE1560.

Tray Formers' First Step