When wood meets technology

When wood meets technology
Flexible automation and robots for the production of multilayer parquet elements.

Avisit to the latest edition of the “Xylexpo 2014” Show dedicated to the woodworking machinery sector last May at the Rho Trade Fair Grounds in Milan provided ample demonstration that the time has come to go beyond rigid, fossilized processes in the direction of newproductive structures that have higher flexibility in mind. The final blow to Traditionalism was recently given by many companies, especially those based in Asia who have made Just in time programming their winning card. The market has changed radically again, even in just the last fewyears, and the merciless competition fromcompanies producers in the developing world has obliged many parquet producers to choose systems that are capable of providing rapid response to variations in client demands.
Reducing times and costs seem to be the factors to bear in mind in the newtechnological processes, and multilayer parquet (erroneously often referred to as pre-finished) is not excepted from these new commercial dictates, and for this reason products now tend to be completed only at the moment of shipment to the client. The advantages derived are excellent because reduced stock levels require lower capital investment.
This latest edition of the XylexpoShowalso demonstrated thatmostwoodworking systems and machines have been computerized by nowand computers permit the management with rapid flexibility of more economical production lots controlled by programs with such simple instructions that they can be programmed by anyone with a minimum amount of training. The robotizing of certain processing phases bywork centers and logistic systems has also rendered processes for both solid single-layer andmulti-layer parquetmuchmore flexible and economical. Robots are mechanisms that repeat a number of elementary operations and therefore raise output. Their widespread use has played a key role in increasing industrial automation.
The Cartesian, hybrid, and anthropomorphic robots presented at Xylexpo 2014 by many Italian and international companies vaunt a reliability that has by now been guaranteed by international regulations. The “automatic factory” is already on the horizon in the foreseeable future, and nowmany companies even in the Orient can offer CIM (Computer Integrated Manufacturing).

The advantages of automatic cutting-off machines

The multi-layer parquet adventure begins with the planning and cutting-off of the solidwood performed on high-quality systems appropriate to every productive need. Automatic cutting-offmachines comewith optimizers that reduce scrap to aminimum, and companies with high productions use excellent cutting-off lines with ideal optimizers that are quick and easy to use (less than 0.002 seconds for all cutting calculations). The conveyor reaches elevated speedswith extremely rapid accelerations and cutting times, while the possibility to obtain different sizes by means of a simple selector suits the cutting-off machines to any need the client may have. There are also cuttingoff machines at the technological vanguard for optimized cuts with translation rollers suited to every size (unworked or deformed) with advance speeds of up to 240 m/min. and width/length readers that provide a summary of the volumes cut.
The choice of the cutting-off machine depends on the maximum section of the solid wood to be cut. Automatic lines require no specialized operators and offer constant output, whereas optimized lines ensure higher efficiency (less scrap and higher productivity) than automatic lines.
Cutting-off machines with optimizers are commonly used to eliminate waste and accelerate the cutting of the more valuable species of woods, but their exceptionally high speed and output permit their use also with types of wood of lesser value.
Defects are displayed either by automatic scanners or by lasers maneuvered by the operator, and can by driven by roller, by belt, and by pusher bar. Disks of 550 mm diameter can be used for cut-offs on solid wood up to 800 mm wide and 25mmthick.
For productive cutting Lathsor fingers formultilayer parquet can be cut by disk or by blade on multi-blade sawing machines, whereas the topandbottomsurfaces of the lath are already suited for immediate gluing.The cuttingunit has centralized electronic control that ensuresperfect cuttingprecisionwith aminimum amount of play (0.1 mm) andfeedspeeds of up to 20m/min.
The use of hacksaw blades provides higher output (20%) than traditional processes, and even permits the cutting of laths from moist wood that is required when two or three layersmust be glued togetherwith high frequency.
The laths and boards for parquet to be cut with boxed blades can be obtained from boards that have been cut-off andworked on three surfaces (using a lateral or central ruler) or on four sides (with guides in the raceways. Both laths and the smaller boards can be sizedwith tool-holders positioned at the end of the cuttingmodulewith up to 0.05 mm precision. Wood laths can be cut to a minimum3mmthickness using 1.1mmtools in satellite (a cobalt-chromiumalloy) for significant increases in productivity. Whereas bladed cutting unit feed speeds can reach 2 m/min., disk cutters can reach 36 m/min. with 1.2 mm thickness and the possibility to have a lower engraver of just 1.1 mm. This results in a 20% higher output in the production of multilayer parquet, and the machine tools used by now all possess planing work centers capable of sizing the boards on all four sides with the possibility to obviously insert unworked smaller boards in the line.

The lath technique

Automated processes are capable of beginning theworking of the solidwood board by planing it and transforming it into laths, and then pairing, pressing, and drying them continuously. The boards are dried in vacuum cells with or without heating plates. The former technology is used in cylindrical vacuumcells in which the vacuumnot only dries but also applies 10 ton sqmpressure on the solidwood boards for further advantages to the quality and speed of the process. The processwithout heating plates is adopted both in cylindrical cells and parallelepiped cells with continuous or discontinuous vacuumandwith hot air ventilation; this system is best suited to making stacks of strips of wood. The market offers vertical saws designed for the top layer ofmultilayer parquet that can be inserted in production lines composed of a lath loading area (with obligatory identical width, whereas the length may be variable), followed by composition and subsequent gluing areas. In the final step, an assembly and drying area provides one single and continuous plank from which compositions of plank of equal size can be obtained fromlaths in two, three, or four rows as required by themodel ofmachine utilized.
The newlines for the gluing of the single layers of themulti-layer element to be laid in two or three layers utilize polyurethane adhesives spread at 120/140 °C or vinyl-based adhesives (70-80 °C) in order to assembly solid and not invulnerable to environmental deformation.
The adhesive is applied in molten form on the layers to be pressed together, while the production of the three-layer element can also usemelaminic adhesive due to its better resistance to chemicals and water. The bonded layers consist of obviously the noble wood top layer (3 - 6 mm thickness) and the other two or three layers of less noblewood species or strips of plywood (from 5 - 10 mm thickness). The adhesive between the solid wood multilayer element’s layers can be made to dry quickly using a high-frequency system by adjusting the power in successive stages (12 positions) and with ceramic triodes.

Not only the finish

Mostworthy of note among the profilingmachines and squaring machines that have by now become totally automated are those (whetherwith traditional tongue-and-groove or on-edge snap fit)with 110mmtool-holder shaft length and feed speeds of up to 70 m/min. suited for the production of parquet with variable width of from 65 to 400 mm and lengths of up to 4m. There are also combined planing-sanding units that permit the dead times that usually occur between these traditional processing phases to be eliminated. As regards parquet logistic equipment, various automatic feeders, loaders, and unloaders capable of forms packs of strips for subsequent working could be admired at Xylexpo 2014.
The alternative to varnish that consists in the heated coating of the multilayer laying element surfaces in just one single passage performed continuously eliminates a number of stages in the traditional process (puttying, sanding, application of the primer and sand ing), thereby shortening finishing times enormously.Many products by nowhave elevated UV radiation stability, excellent impact strength, optimumhardness, and good chemical resistance. These products are applied liquid using a pre-heater and then solidify at roomtemperature. These short narrowstrips require three or four days of storage before they can be profiled, however.

The world of varnish

For those who use traditional processes, water-based varnishes – the only ones with respect for the environment – have been available in themarket for quite some time now, even if they have often been overshadowed by solvent-based products that are easier to sell. Painting systems are designed on the basis of the type of paint and finish desired by parquet producerswhile also bearing in mind the possibility for light or heavy staining.
Despite the fact that application and drying systems and cycles vary widely, there are also versatile polyvalent machines capable of being quickly and easily set up for the desired type of finish. One multilayer parquet element varnishing process that is being adopted all around theworld utilizes three coats of primer applied by roller, each of 10 g/sq m thickness.
The process consists of an intermediate semi-polymerization, a final polymerization with a subsequent intermediate sanding followed by two finishing coats applied by roller of 10 g/sq m each,with an intermediate semi-polymerization and a final UV polymerization. The system can have minimumwidths of 30 cm.
and the machines used include: lacquering machinewith standard rollers (providedwith applicator roller and dosing roller with three separate commands that permit the dosing roller to rotate in opposite direction whenever minimum applications are required), UV-module driers (that polymerize varnishing products in just a fewseconds, to which photoinitiators are added) and intermediate sanding machines (used to smoothen the surface with primer and prepare it for the application of the finish). The technology behind UV paint products permits elevated output and permit the use of minimumweight formats with noteworthy savings of material.
Paint and varnish producers have by now specialized and diversified their products by type of finish and by cycle. This means that acrylic- and UV polyester-base primers and finish coats formulated for extremely short cycleswith high abrasion resistance and excellent adherence and elasticity can now be found in the market.

barberan machine


The productive process future, which will most likely be based on automatic fabrication with CAM(ComputerAidedManufacturing) and CIM (Computer Integrated Manufacturing) management keeps getting closer and closer. It is also an accepted fact that robotizing certain processing phases, innovative work centers and logistic systems combined with more and more flexible and personalized productive cycles and processes will provide considerable advantages in both productive (shorter and shorter fabrication timeswith higher and higher output and efficiency) and economic (lower overheads and rationalized resources) terms, in addition to greater abundance of the offer. In my opinion, all this should not lead to standardization but rather the contrary: the objective and real possibility of access tomore innovative single devices, machines and production lines should stimulate entrepreneurs to improve the quality of their products.
Even if they are elementary in form, the above is always the result of a specific project that through a precise and analytical technical-productive procedure that permits the discovery of personalized solutions by involving the company first and foremost of all. These are the forms of personalization that characterizemultilayer parquet andwood flooring elements thanks to the quality of the tools, equipment, machines, systems, and lines that permit the fabrication ofmillions andmillions of laths, boards, planks, and maxiplanks for every taste, every day.

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