A band knife or bandknife is a power tool used for cutting cloth and similar soft sheet materials. Very similar in operation to a band saw, it has an endless loop blade and the material to be cut is supported by a flat table. Band knife blades also have applications for cutting/slitting or converting foam. Band knife blades are also used for splitting leather, paper, EVA/Rubber and Carpets.
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Band knife machines
Band Knife blades are used on two types of machine (vertical and horizontal) depending on the material being cut/processed.
Vertical
On a vertical band knife machine usually a narrow width band knife blade is used, the most common width being 10mm. The length of the band knife blade depends on the supplier of the band knife machine. The dimensions are indicated on a small metal tag pasted or riveted on the machine. The vertical machine band knife blade is most commonly a "double bevel, double edge DBDE" execution to enable cutting while advancing the table and also while retracting the work table, while as the "double bevel, single edge DBSE" execution cuts only in one direction. Productivity is enhanced when the operator cuts both while advancing and also while retracting the work table after adjusting the foam block after each pass for cutting. The DBDE execution blade can have a parallel or twisted 180 degrees welding. The twisted welding execution saves a grinding unit, as both edges pass the same grinding unit after two turns. It has been observed that a narrow width on a vertical band knife machine gives better dimensional accuracies on the foam block. The wider the vertical machine band knife - more the deflection and size variation from one end to the other extreme end.
Horizontal
Horizontal band knife blades are wider usually 30-60mm wide for foam converting is popular, for leather goods 40-50mm wide blade is popular, 85-110mm width is popular for the tannery splitting band knife. There are other widths depending on the machine manufacturer. The horizontal machine band knife blade is supported by a guide to give dimensional accuracies while cutting/splitting. Therefore, only blades that have passed as one main manufacturing step a surface grinding process reach the necessary thickness tolerances of less than 0,02mm. A higher tolerance would lead to marks on the surface of the split material like leather or rubber. Blades are available in different grades of exactness depending on the required exactness on the material to be cut/split. On modern machines in combination with a high grade blade a splitting thickness of 0,2mm for 1500mm material width is possible.
Blade sharpening
For both the vertical and horizontal band knife machines there is a grinding attachment which continuously sharpens the band knife while it is cutting. It is possible to find a nonpowered grinding attachment for the vertical machines but for the horizontal band knife machine the grinding attachment for continuously sharpening the blade is powered by electric motors.
History
Before WW II: several machinery brands on the market: Turner, Clasen, USM, BMD,