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A better cut

SolWoTM has developed an innovative new method for sawing wood and other non-magnetic materials that is capable of producing dimensionally accurate products and top-quality sawn surfaces with minimum waste. It is based on a patented magnetic blade control system that automatically monitors the position of the saw blade and keeps it on track for a consistently better cut.

A number of solutions have been developed to resolve the problem of saw blade deflection over the years. Rollers and guides have been tried, for example, but the best-known method has probably been the use of thicker saw blades.

There are drawbacks to this approach, however, despite the fact that a thicker blade does deviate less from the intended sawing line than a thinner blade. In particular, thicker blades produce more sawdust and reduce the amount of sawn timber than can be produced from a given amount of raw material.

Increasing blade thickness means increasing the amount of raw material that is wasted, and this can be very costly when processing high-value materials, such as hardwoods, panels, and semi-finished parts, such as parquet billets and sandwich board.

A different approach

SolWo encountered the problem of blade control during production trials for extra-thin gluelam board material, and began work to find a solution that could be used in a wide range of applications.

Saw blade performance with and without SolWo's electromagnetic control device.

When the idea of magnetic blade control was proposed, it soon became apparent that very little relevant scientific knowledge was available. Working with local partners, the Technical Research Centre of Finland, and Lappeenranta University of Technology, SolWo developed a new type of magnetic blade control.

SolWo's control device monitors the position of the blade inside the material as much as 100 times per second, and makes any necessary corrections by adjusting the electric current supplied to the magnets. As a result, the blade can be kept very accurately on the intended saw line.

Precise control

Using magnets to control the blade is friction-free, which means that no parts have to be replaced because of wear and tear.

Thinner band saw blades can also be used, as the forces applied by the magnets eliminate the side forces that tend to twist the blade in a conventional design. In the case of circular saw blades, magnetic control means that blade guidance is no longer dependent on internal tension within the blade, and these blades can be made thinner too. As thinner blades can be operated at higher speeds, it then becomes possible to raise feed speeds.

Some early prototypes of SolWo's electromagnetic control device.

Blade manufacturers are already testing blades less than 0.8 mm thick, which will enable speeds to be increased significantly. Much higher feed speeds are set to revolutionise the entire industry.

As SolWo's magnetic blade control system is very precise, the sawn goods that it produces are very dimensionally accurate and have very high-quality surfaces. Raw material is utilised much more efficiently and less sawdust is produced. The ability to produce higher quality products with less waste obviously translates into better profitability for sawmills.

The SolWo system combines consistent product dimensions, higher feed speed, and greater cutting depth.

Great potential

The patented SolWo system can be fitted to new and existing saws, and is suitable for both band and circular saws cutting virtually any non-magnetic materials lengthwise, including wood, stone, aluminium, and plastics.

Even very thin board, only 1 to 2 millimetres thick, can be produced highly accurately. Tests have shown that the method has a clear potential to improve sawing in a variety of applications, particularly higher value-added areas.

SolWo's first-generation products have already been tested, and further development work is ongoing. The principal markets for the technology at the moment are gluelam woodboard, round wood, and panel materials, although it can be used with virtually any non-magnetic material.

> Janne Pyrrö
(Published in High Technology Finland )