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WHAT YOU DO NOT KNOW ABOUT WOOD

 
GENERAL INFORMATION:
In the wood industry, veneer are defined as thin sheets of wood (thickness from 3 to 30 tenth of a millimeter ). Veneers are added together, creating panels that are then glued and pressed on less noble wood and / or on any type of raw panels (plywood, particle board, laminated plywood, honeycomb, etc.) to obtain components of furniture, doors or furnishings, made of valuable wood and well illustrated, but with lower costs and greater beauty.
The veneer is used in the wood industry to reduce the high cost of valuable woods. In fact, these high cost woods are best used in the veneers operation because, compared to solid woods, they can give wooden items with greater stability and lower risk of termite attacks. Furthermore these items are more homogeneous in mass production, and with more care in selecting the visible parts.
A well veneer furniture fixed on a good support, like the multilayer, is more durable than a furniture made of all solid wood.
Using wood veneer, also meets the needs of an eco-friendly exploitation of wood resources. From a single piece of wood can be made many fine furniture (you can get from 700 to 1000 square meter of veneer per cubic meter of the trunk, depending on the type) and made the rest with plantation’s wood.
Unfortunately, today the need to reduce costs (especially labor costs) and the lack of good wood, means that many companies use, as an alternative to veneer, petroleum products (laminates, melamine, formica, ABS, plastics) or cards reproducing photographs of the wood.
The furniture produced with such surrogate, by the end of their cycle of use, unlike almost all the furniture made of wood, should be disposed of in approved landfills.
Veneer may assume particular shapes depending on the angle at which the veneer knife cuts the log met in different ways the growth rings. Each wooden essence produces distinctive shapes.
The name veneer derives from the fact that the log is sliced by a blade that, without production of sawdust, cut lengthwise in the log. The trance arrive at the current length of 5.2 meters.
There are several systems for cutting; usually always in the longitudinal direction of the trunk and without production of sawdust, and almost always to do on hot logs and treated with steam:
1)      the most common, the trunk is locked by hooks on a surface on which the knife, well pressed, meets the trunk. For each cut, the plan approaches the knife to a thickness programmed, these machines can be horizontal, vertical or inclined.
2)      In some types of vertical shearing, the log is fixed and the knife goes up and down and move forward of a planned thickness;
3)      On sheeters, the log rotates on itself, and at every turn, it meets the blade and move forward of the programmed thickness. In this case, we say peeled ( this is the system used for the production of plywood and multilayer wood used as a support with very wide sheets; and also used for burl).
4)      On a new machine, called semi rotary, the log is set at a plane that rotates 360 degrees and meets the knife at every turn, but the tour takes place around an axis that is 50 to 100 cm offset from the position of the log, which is more external.
 
 
 
 
Quarter cut veneer
The log is first squared by a band-saw cart and then cutted in direction parallel to one of the faces, obtaining a veneer that, tangentially encountering the wood fibers, describes drawings like an inverted V, called crown.
 
French cut
The log is split with a band saw cart into four parts or with big circular saw blades into three segments and each quarter (or every third) is sliced parallel to the median radius of each quarter, getting a veneer that, meeting with the wood fibers radially, get a parallel fiber design called quarter cut (this method is only applicable to the trunks of large size).
 
Swedish cut
The log is divided as in the French cut, but is sliced perpendicular to the median radius of each quarter, getting flamed veneer.
 
Italian cut
The log is cut into two half crescent and, after cutting the four points, is sliced from the narrow side to the heart and then from the heart to the opposite narrow side, obtaining a veneer that get a cut that will meet the wood fibers, first in a tangential way, getting cut half crown, and then striped and then again half crown (this system increase the amount of stripes on small trunks).
 
Manufacture of veneer
After the cutting the wood is dried, once in the air, today in mechanical dryers at a temperature that allow the wood to dry just in some minutes. Today some modern dryers "stretch" the veneer by reducing the innervature. Then after a rest period to allow heat loss, and an additional natural ironing, the parties still “nervous” can sometimes be stretched into special presses.
 
 
The sliced log is then trimmed roughly to the side and head, collected in parcel of 32 sheets (the thickness is 5 / 10 mm or if different thickness different number of sheets) and numbered parcel by parcel.From a log you get more parts of it, two parts for small logs cutted using the quarter cut or the italian cut, four using the french or swedish cut, but there will be many more pieces if the log is big and is cutted in more pieces and then sliced.

 
Veneer may have special characteristics when made from special parts of the log such as feathers (the upper bifurcation of the log in two branches) where the central part of the sheet of veneer often describes a gradient of fiber in the form of a feather; the burl or round parts that sometimes emerge from the stem of the log,hiking boots made from the roots of some trees, the marbling or frisé that are derived from overlapping fibers.
The wood sold in pieces, or whole body is then spliced by users.
 
JOINT VENEER
To perform the veneer of the panels, added with matching edges, a number of cut neatly taken from the same package (called staves) is required.The stages are as follows:
  • Squaring: phase of cutting the heads of the parcels of cut in perpendicular to the direction of the wood grain;
  • Trimming: cutting phase of the parcels of cut parallel to the direction of the wood grain;
  • Adjunction Wire: adjunction sheets sliced through a wire-melt;
  • Adjunction glue: adjunction of the sheets of veneer with glue;
  • Adjunction to paper: adjunction of veneer sheets using paper (used for the production of inlays).
The arrangement of the cut to form a panel may be in the following ways:
  • Parallel or running (Each sheet is provided with the right edge against the left edge of the next sheet)
  • kissed or book or open (each sheet is provided with the right edge against the right edge of the next sheet).
 
In the first case you can also use cut from different logs of the same type and is called joined strips. In the second case are called figures veneer, that are cut to match the half crown, crown and quarter cut parties in the same trunk on the panel for uniformity of color and fiber.