Resumo

COSTA, Augusta  e  PEREIRA, Helena. Characterization and Tield Analysis in the Preparation of Vork Planks for the Industrial Processing into Cork Stoppers. Silva Lus. [online]. 2004, vol.12, n.1, pp.51-66. ISSN 0870-6352.

The industrial processing of natural cork stoppers, the most profitable cork product, begins with the preparation of the cork planks. The raw cork planks are boiled in water and then manually cut by expert operators into smaller planks of homogeneous thickness and quality. This operation originates the first cork wastes in the industrial process. The cutting of the cork planks was studied with a random sampling of raw cork planks taken from one industrial unit after boiling, for which a virtual cutting was made following the markings done by skilled operators. The dimension and shape of the cork planks were analyzed as well as the potential maximum number of cork stoppers to be produced. The area, length and width of the raw cork planks are related with the shape of the tree stem and branches and with the cork stripping techniques, while the dimensions of the prepared cork planks are related to the specificities of the manual handling in the following operations in the industrial flow. On average, the cutting decreased the cork plank area to half. The wastes consisting of small pieces represented 5% of the initial raw cork. The analysis of the maximum potential yield of cork stoppers showed that the regions of the raw cork planks that do not allow the cutting of cork strips for the punching out of stoppers or their excess length represent a waste residue amounting to 17% of the cork plank area. The potential maximum number of cork stoppers depended directly on the plank area but the proportion of waste showed a decreasing trend with the increase of the plank area. In order to maximize the yield in the production of cork stoppers, raw cork planks with large dimensions should be used, taking into account the probable need for automation in the industrial cutting of cork strips.

Palavras-chave : cork planks; cork industry; natural cork stoppers; preparation; cutting process; yield.

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