PRODUCTION PROCESS
Our production process is divided into 2 parts.
- PRODUCTION PROCESS OF WOODEN SHELLS
- PRODUCTION PROCESS OF METAL FRAME
- Tube Bending and Welding
- Electroplating or Powder Coating
BENDING WOOD
The process begins with the pressing of glued veneer layer in their predetermined shape.
Bending wood is a very complex process, before pressing it is decided whether the veneer are to be processed into plywood- if so then the veneers need to be placed on top of each other crosswise to the grain direction or if laminated wood need to be produced the individual veneer layer need to be placed parallel to each other.
Laminated wood can withstand huge tensile loads yields flexibly and then swing back into its old shape. Plywood is stable in form and has a very high rigidity.
Accordingly here in the pressing process the veneers must be attached to each other and laminated on top of each other. Any variance in the thickness within a shell is also applied here. Every model of wooden shell has its own forming tool. The glued veneers within the forming tool are subjected to very high pressure of up to 300 tones for a precisely calculated time. The duration of the press further depends on the mode of heating which can be done electrical heaters, or steam or maybe by high frequency.
Veneer layer which are glued under high pressure and heat forms a new shape with high static quality. However as per the requirement they can be made more or less flexible.
PROCESSING BENTWOOD
In this part we will brief about our bentwood production quality, which is an art of processing the bentwood shells in such a way that it is accurate in its dimensions and perfect in its finish. This is the necessary prerequisite to exclude almost completely the possibility of production problem arising during assembly.
This accuracy can not only be measured but can also be felt. The joints don’t fail by even a fraction of a millimeter, not a slight un-evenness in the armrest. In other words everything fits perfectly, accurately, 100 percent, one after the other. And if somebody is used to the thinking in terms of craftsmanship this requirement will hardly be possible, because the quality of any manufactured piece will depend on the precision of the individual parts. If one places two items of hand craft piece next on one other deviation will clearly appear to be the normal rule.
If you look at our piece of furniture as a whole, you will notice at once why it has turned out differently from hand crafted furniture. It is because human capacity for accuracy is not enough to achieve this quality. It is necessary to work with strict precision that only machines are able to process, time after time. Every cut, every drilled hole, every groove is positioned on the part to an accuracy of a millimeter.
Work piece clamped into position.
This is the only action human hand has to take. The piece must be processed from the first to the last being at the same position. This ensures the series of production accurate to a fraction of a millimeter.
In order to achieve this we use computer controlled machines every where, where this quality is required. The human being takes on the role of machine controller and supervises its operation 24 hours a day. The machines decide the start point, the correct depth of the groove, the length of the curve. The resultant quality is proof what we are pursuing here.
The process starts with the work piece being clamped on to the machine table. It is then worked on with various tools like milling, saw, drill, sander etc without being touched by a human hand. The machines are fitted with automatic tool changers which ensure a complete series of operation without the work piece being moved from its original position. The crucial advantage of this principal is that CNC machine can carry out and co-ordinate the movement of various axes at the same time. This makes the spatial processing possible with very high repeat accuracy.
The process sequence
The CNC machine runs preciously through its program, in this example the cutting head is making a series of grooves on an L shaped shell. The technology guarantees that the grooves are all exactly the same distance apart, and their dimensions are accurate to within one tenth of a millimeter. To achieve this, the CNC machine head steers automatically along the seat shell and starts making the groove. This process ensures that all the pieces produces under this program are identical and will fit every chair at the time of assembly.
VENEERS FOR AN ATTRACTIVE FINISH
Approximately 4000 years ago, the Egyptians discovered how one can use wood sparingly and nevertheless generously. The raw material of wood was scarce in northern Africa, but its aesthetic quality was appreciated. They used the thinnest possible boards to cover a large area with only a little material. It was used particularly to beautify rooms.
Today producing veneer is an industrial activity where trucks are cut layer by layer or are peeled by large and highly precise machinery as at Bentwood Seating System. Peeled veneer can be manufactured in large pieces without joints; they usually have a thickness of only 0.6mm to get as many square meters as possible out of the valuable shell.
Today veneers are produced in India from wood imported from around the world. The most important type of wood for covering veneers in bentwood parts are mentioned below.
Beech / Cut Veneer. Beech is found in all of central Europe. It is marked by its simple structure with scattered fine pours. It is pinkish in color. It can be easily stained or lacquered. The veneer has straight or angular grains and the veneer sheet is formed by joining narrow strips of veneer.
Beech / peeled Veneer. Peeled Beech veneer has the same characteristic as that of beech cut veneer, but more lively. There are no joints; the veneers are thicker and stress resistant. The veneer have flower or oval shaped grains.
PAINTING
Wood painting is a practice that springs from two basic needs to protect and to decorate the surface. The articles in our home from windows to furniture are not just functional.
They need to be more than just protected; they need to decorate our rooms. They must therefor be made to look attractive. They need to be protected from rains, from UV rays from bacteria, but also from the detergents with which they are normally cleaned and from physical aggression to which they are exposed during use.
A paint product is basically a mixture of chemicals which, when applied to a surface are able to form a solid, mechanical and chemical resistant film possessing properties that also change the decorative characteristic of article in relation to color aspect and texture.
All paints products are fluid obtained by mixing various components together. These components can be groped as binders, pigments, solvents, thinners and additives.
Binders – They are also called polymers or resins in practice. They are film producing agents which determine the main properties of paints. Substantial characteristic like gloss, surface hardness, abrasion resistance, chemical resistance, ability to withstand thermal cycle all depends on the type of binders. Binders are therefore the most important ingredient of paint. In order to obtain the best result the right series of binders should be used.
The film may be produced in two different ways either physical filming or chemical filming. The physical filming occurs when the solvents inside the paints evaporates, a hard paint surface is formed. This hardening is reversible since solvents can transform the binder into a solution again. For example nitro lacquer like Melamine paints. These paints have a lower ability to with stand scratching and abrasion as the surface hardness is poor.
The chemical filming occurs when the paint hardens after a series of reaction within the binder when it comes in contact with the oxygen present in the atmosphere generating complex structure. These structures have very high surface hardness and are able to withstand scratches and abrasion to a very large extent. For example Polyurethane paints.
Pigments – They are insoluble coloring substances which are added on to the binders to get a colored surface. The quantity of these pigments in the binder decides the transparency of the paint film. A high quantity of pigments makes the surface look absolutely solid. The lower quantity makes the wood grain underneath to remain visible.
Solvents – They are liquid substances which are able to dissolve binders in order to make it easy to apply on the surface of wood.
Additives – They are added along with the pigments to improve the performance of the product. For instance anti yellowing additive is added to reduce the yellowing effect on the painted film caused by exposure to the light.
In order to save perhaps 10% of the value of finished products we stand to loose the remaining 90% of its value if proper paint selection is not taken care of.
UPHOLSTRY
Putting no limits to the comfort requirement upholstery is done on the wooden frame with a backing of Polyurethane foam. We have installed the most modern plant with automatic stitching machine, cutting machines and other leather processing machinery from Germany and Italy.