Wood veneer
As veneer 0.3 to 6 mm thick sheets of wood are referred to, which are separated by different sawing and cutting process from the tree. The word veneer was in the 16th century the French " fournir " ( equip, supply ) borrowed. It described the process to use less valuable wood with nobler thin wooden sheets.
- 2.1 precious and veneers
- 2.2 Under veneers
- 2.3 Blind veneers
- 2.4 Absperrfurnier
Manufacturing / cutting process
The simple veneers are usually caused by peeling of logs generated ( peeled veneers ). For decorative surfaces also come gemesserte, rarely sawn veneers are used ( sliced veneer and sawn veneers ).
Rotary cut veneer
Before peeling the logs are, depending on the species, cooked in large Dämpfgruben (stems are completely in the water - the temperature may well be below 100 ° C, the water does not have to cook ) or attenuated (stems only have contact with water vapor; depending on the process the temperature is over 100 ° C ) to make the wood smoother. Here, the natural color of the wood partly changed considerably. A few types of wood are soft enough to make them even without this process - in "raw " - further processing. After the log is debarked and then clamped like a roller rotatable. The tribe then rapidly rotated around its own axis against a knife bar that separates a veneer tape from the trunk; similar to the unwinding of a kitchen roll. The veneer tape is then divided into small, individual veneer sheets by beating or vertically rotating blades (called Clipper ). The veneer sheets in thicknesses ranging from 0.5 mm to 1.5 mm mainly be further processed into plate-shaped wood materials such as plywood, plywood or blockboard. A special feature is the processing of veneers to form plywood, another producing veneer of birdseye maple, with a structure that is only on the outer circumference of the stem almost exclusively in the veneer to bear due to the occurrence of these masers buds. Another specialty is the wood grain, which is obtained from burls, often to the finishing points ( grafting ) are formed by uncontrolled growths. So-called root veneer is rarely made from the root of a tree, but is a colloquial and incorrectly used name for Burl veneers.
Sägefurnier
The oldest method of manufacture of veneer is the saws. From trunk the veneer sheets are separated with a saw, in the pre-industrial era often lying with the tribe over an open pit. A person standing in the pit, the second was on a scaffold on the trunk, sawn with a frame saw. Go to the top of the 19th century, the first powered by steam power veneer saws have been developed. In England and America were the huge highly specialized circular saws with blade diameters of up to 4 meters, while permeated the shape of the frame saws in continental Europe. In 1900, the highest development of maturity of such machines was achieved, however, the production of sliced veneer lossless meant the end of the industrial Sägefurnierherstellung.
Since when sawing veneers, depending on the used saw blade and depending on the thickness of veneer produced about 50 % to 80 % of the tribe to sawdust and waste are, this is a complex and prone with high material loss method. But there are some good reasons why even today sawn veneers with typical thicknesses of 1.2-2.5 mm, 5 mm, 7 mm and 10 mm are produced and sold:
- The sawn veneer retains its bright, natural color and will not change color much as in slicing through the often day-long cooking to Geschmeidigmachung for the knife process.
- The veneers are always present in gemesserten susceptibility to cracking and fractures, particularly of the knife side remote is completely eliminated with sawn veneers.
- Many woods can only be processed to Sägefurnier by their high hardness above a certain strength. So there is no other method, for example, palm wood, iron wood or snake wood to be processed into veneer.
- Longevity of objects with a given by the thickness of the veneer work-up opportunity.
For many discerning craftsman Sägefurnier comes again today to use when it comes to producing high quality individual single units: often charge customers for durable solutions in the construction of expensive design furniture that almost paper-thin veneers are at after damage, for example a table top no longer repaired or worked up. This is where the use of Sägefurnieren to manufacture durable, often usable generations furniture. Since furniture although nowadays these are built always short-lived, it loses its importance.
Sliced veneer
In diameter, the logs are first boiled or steamed and then clamped to a so-called sleigh. Either of these horizontal ( older machines ) or vertically ( new machines ) against a knife. Some manufacturers put in the latest generation of machines instead of a moving blade, wherein the strain remains in a fixed position. For each operation, a knife blade veneer is produced which is thick at low cut veneer between 0.4 mm and 0.7 mm. Stark cut veneer, but loses due to the economy in dealing with the raw wood and alternative products is becoming increasingly important is sliced to a thickness of about 6 mm, but this is a very heavy machine requires (usually horizontal slicers from the years 1960 - 1975). The so gemesserten veneers have over the Sägefurnieren the advantage that the loss eliminated by the saw cut, but can be such thick veneers used only for quality grade applications such as shutting off wood surfaces since the severe cracking (knife cracks ) in the manufacture makes a durable surface treatment impossible.
So-called micro - veneers are even manufactured in thicknesses between 0.1 mm and 0.2 mm, but this requires special machinery, the diameters in the direction of the wood fibers, rather than in the ( approximately ) 90 ° angle to this. This method is particularly and almost exclusively popular in Japan, but such veneers require lamination films to the substrate, since the veneers themselves are transparent.
Veneers are primarily as a visual veneers on inexpensive substrate material ( usually particle board, plywood, MDF or HDF) applied.
Stay- production
This type of production is the veneer production very similar, but is mostly marketed and processed as sliced veneer. Here, the strain is not rotated about its own central axis, but is seated on a rotating holder. This is also referred to as eccentric blades or peeling. This can be produced either a very narrow veneer picture or a particularly wide patty- engined image.
Use
We distinguish between the following types of products according to their areas of use:
Precious and veneers
These are used for allocating disk material or other material to produce a fine wood finish. For this purpose, most are veneers, rarely used the expensive sawn veneers. Particularly nice results can be achieved with expensive burl veneers, which are obtained from growths.
The veneer can be assembled into different "pictures":
Imposed, even pushed, ranked
Head thrown
Other examples of the use and application of fine wood veneer see wood.
Under veneers
These are introduced rotated at high quality work as an additional separation layer between the substrate and veneer by 90 ° in the direction of the grain. This will prevent damage to the carrier material shine through the face veneer or foresee the glue joints of the (possible) edge band. Under veneers are usually made of sliced veneers of inferior quality and higher thickness than the later visible face veneer.
Blind veneers
" Blindfurniert " be with so-called " counter-draw veneer " veneered surfaces called that are no longer visible after installation of the workpiece, such as the insides of a pedestal. This is necessary because the substrate with time could be forgiven by unilateral veneer. For this inferior quality are used with optical errors generally veneers.
Absperrfurnier
Such veneers are referred to " shut off ", the plate in the manufacture of plates, that is intended to prevent further movement and changes in the carrier plate. This is especially true for the core board. This consists of long, narrow wooden rods to which the Absperrfurnier - is glued offset by 90 ° - relative to the direction of the grain. For veneers usually peeled veneers of thicker starch may be used as a normal Sliced veneer for larger widths available.
Processing
Veneers are assembled prior to processing mostly veneer ceiling ( " Spliced " ), so that the application can be done on a plate in a single step. The individual veneer sheets are trimmed and then glued to either shock or " stitched " with a zigzag running glue thread.
Economic Importance
Only the most valuable woods are used for the production of veneer deck, and these are mainly hardwoods. Here are dominating beech and oak, each with about 30 percent market share. Maple has ten percent market share. Birch, cherry, ash and softwoods move in a frame of five to seven percent. In Germany, around 30 companies are active with approximately 1,000 employees mainly in the veneer industry. The main customers of the veneers are mainly industrial processors (in particular the furniture industry). Other customers include the interior design and the carpentry and boat building / yacht builder and the automotive industry.
History
The veneer technique was ( 1332 BC) already used by the Egyptians in the 18th Dynasty. In sparsely wooded Egypt precious woods were as sought after as rare. This forced the Egyptians to the economic processing possible way. They cut the wood into thin sheets and then attached them with glue and simultaneously with fine wood pencils on less visually attractive wooden surfaces. 1922 veneered furniture pieces were found as grave goods for Tutankhamun - witnesses of an ancient Furniertechnik.
In some periods of art history, for example Louis XVI, Biedermeier furniture without decorative veneers would not be handed down to us way conceivable. Many of the timbers used were massively not available in sufficient quantities or simply too expensive for massive constructions. Decorative techniques such as multiple attached images or wood inlays were made possible by veneers in the broadest sense. In France, for the first time in 1657, the professional title Ebenist (from French ébène, ebony) is that found use for cabinet makers, which mainly veneered furniture manufactured.
Our contemporary furniture, flat doors and molded wood products make clear what a dominant role has reached the veneer.