Program-controlled stacking and unstacking lines, mostly in connection with beamsaws or CNC machining centres designed for nesting production.

Areas of application

If the cutting process requires both high performance and very flexible material composition, automatic stacking and unstacking systems are used. In a so-called area storage system, different panels (quantity, quality) are stocked as required and removed by a programme-controlled, automatic storage and retrieval system, fed to the processing machine, removed and stored or deposited.

The advantages of these systems lie in the fast and flexible handling of individual panels, the decoupling of cutting and material supply, the possibility to monitor a large spectrum of parts and to precisely feed them to the machines connected to the storage system in a process-safe manner. By means of appropriate software, material consumption, material management of residual quantities and ordering can be organised.

Types of storage

Fixed allocation/ fixed storage

Single-variety material (e.g. panels) is stored or removed from predetermined, fixed storage locations. Preferred storage type for material with high stock turnover (colloquially strong runner).

Dynamic allocation/ dynamic storage

Single-variety storage, whereby, in contrast to the fixed storage order, the storage bins are not only assigned to one material, but to a (dynamic) material group. When the first part is placed in an empty bin, this bin is reserved for this material group. Use: Useful when storage capacity is low, e.g. when strongly fluctuating quantities of "heavy runners" need to be stored.

Chaotic allocation/ chaotic storage

Different parts are stacked on top of each other in one place, for example. This type of storage requires restacking and keeping at least one other "chaotic" storage space free for intermediate storage of the chaotically stored parts. This space-saving, but time-consuming type of storage is used for so-called seldomly needed material. Intelligent warehousing software can ensure that stock transfers or pre-picking take place during storage waiting times.

For further technical solutions for feeding production systems, see technical terms: Feeding, Pre-stacking table, Stack storage

Factors affecting release and absorbency

• Temperature:
• Higher temperatures and cooling create an inherent vacuum.
• Workpiece surface:
• With smooth surfaces, the adhesion force increases.
• With rough surfaces, micro-hooking occurs.
• Workpiece thickness:
• The smaller the workpiece thickness, the greater the effect of temperature and surface condition.

Limits and guide values of absorbency

Essentially, the question is whether the vacuum for lifting the top plate can be set so that only the top plate can be reliably lifted. Coated (non-absorbent) panels are unlikely to cause any problems. Raw (uncoated) chipboard or fibreboard is considered problematic. Basic rule: the thinner, the more problematic.

Empirical values - material-dependent, not binding, to be checked by tests if necessary (as of 2021):

• Chipboard, raw up to approx. 12 mm
• not separable and absorbent
• Chipboard, raw up to approx. 14 mm
• not reliably separable and absorbent
• Chipboard, raw from approx. 14 mm
• can be cut and sucked with the support of blowing (overpressure cutting) or vibration (vibration cutting)
• Plywood panels, raw from approx. 14 mm
• Suctionable

Update (2023)

• Modern sensor and control technology makes it possible to push these limits to ever more precise suction traverses. For example, raw chipboard standard E1 from 6 mm thickness and raw MDF from 3 mm thickness are considered separable if the surface storage system is equipped accordingly (source: HOMAG STORETEQ S-200/ TLF-212 with traverse ST 61).