Author: Julia Mihajlova
- PHYSICAL CHARACTERISTICS OF MULTILAYERED PLYWOOD MADE FROM BLACK PINE VENEERS
The research presented in the paper is directed to creating possibilities for production of multilayered plywood that are resistant to prolonged water impact, as well as to mutual impact of water and heat.
The aim of the conducted research consists of the possibility for production of stable multifunctional plywood made from coniferous raw material. For that purpose experimental multilayered plywood panels are made from peeled black pine veneers bonded with water-soluble phenol formaldehyde resin.
The experimental panels were subjected to standard laboratory tests in conditions of water regimes in order to define the water resistance and dimensional stability under water impact and mutual impact of water and heat, as well as to determine the degree of adhesion between the veneers.
The research showed that panels were characterized by high stability during this kind of treatment. The panels showed consistency in form and dimensions, as well as consistency of the adhesion in glue lines.
Keywords: multilayered plywood, black pine veneers, phenol formaldehyde resin, physical properties, resistance to water and heat
- METHODS FOR ASSESSMENT OF SUPPLIERS OF RAW MATERIALS AND MATERIALS (UREA-FORMALDEHYDE RESIN)
Raw materials and materials form a big part of the cost price of the end product. At the same time, the deviations from the requirements put forward to them impede the manufacturing processes, lead to additional expenditure for elimination and compensation of the discrepancies of the raw materials delivered, serious losses and lost profit for the manufacturer.
The provision of raw materials and materials of constant quality is not always achievable and that is why it is necessary to assess the deviations from the optimum requirements and to determine what it costs to us to eliminate / compensate them and at minimum expenditure at that.
In the report, methods for assessment of suppliers of urea-formaldehyde resin are presented. They reflect the relationship between manufacturing and financial indices (price, expenditure, lost profit) when assessing the losses from deviation in the raw materials quality.
Keywords: methods, assessment, quality, supplier
- SELECTED PHYSICAL AND MECHANICAL PROPERTIES OF COMBINED WOOD BASED PANELS FROM WOOD FIBERS AND SAWDUST
The production of wood fiber mass is a very energy-intensive process This is also one of the reasons for the higher cost of this material in comparison of that at particleboards. One possibility to partially solving this problem is the inclusion of industrial wastes, which has not undergone a refining process, in MDF composition.
There is a significant amount of industrial wastes resulting from logging – these are mainly the sawdust resulting from the processing of solid wood with a band saw. It should be pointed out that this method of obtaining solid wood materials is widespread, both globally and in Bulgaria.
This report presents a study on the influence of the content of coniferous sawdust on the properties of combined panels from wood fiber and sawdust. Produced panels were with variation of sawdust content from 0 to 50% and respectively the fiber content was from 100 to 50%. The increase in sawdust content was with a step of 10%. The main physical and mechanical properties of panels were determined and experimentally-statistical equations for the influence of coniferous sawdust content on the properties of the panels were derived. It was determined at what percentage of sawdust the panels have properties that meet the requirements of the relevant standards for MDF.
Keywords: MDF, refining, combined wood based panels, coniferous sawdust
- PHYSICAL AND MECHANICAL PROPERTIES OF COMBINED WOOD-BASED PANELS WITH PARTICIPATION OF PARTICLES FROM VINE STICKS IN CORE LAYER
The growing needs for wood and the impact of forest ecosystems on the climate of the planet require the rational use of wood raw material. One possible way to "save" forests is to increase the use of agricultural lignocellulosic residues. The research efforts of scientists around the world are aimed at improving the properties of wood-based panels and to increase the share of agricultural residues in that production.
In laboratory conditions were produced three-layer combined wood-based panels with a face layer of wood fibers and a core layer of wood and vine sticks particles. The participation of vine stick particles in the core layer was: 0; 15; 30 and 45%. As binder was used urea-formaldehyde resin. The content of resin in core layer was 8; 10; and 12%. The properties of the panels with and without participation of vine particles were compared. The final data for physical and mechanical properties of the panels, with participation of vine particles, were processed by the methods of regression analyze.
In the result of conducted study was established and analyzed the influence of the participation of particles from vine stick and resin content on the physical and mechanical properties of combined wood-based panels.
Keywords: combined tree-layered wood-based panes, wood fibres, vine sticks particles, physical and mechanical properties