Splitting band knife. The splitting band knife (or band knife or bandknife) is a kind of knife used in several fields including: tannery, EVA/rubber, foam, cork, shoe and leather goods, paper, carpet and other soft sheet materials. It is a power tool which is very similar in operation to a band saw, with an endless loop blade; the material to be cut is supported by a flat table.

Technical characteristics
A splitting band knife can be produced in different sizes (length x width x thickness) according to the splitting machine on which it has to be fitted.  Different technical characteristics define the quality of the product (blade)

The blade can be welded and bevelled, toothed not rectified, rectified on both edge and surfaces, with pre-sharpening made by tools or grinding stones.

A splitting band knife can be produced in several dimensions, usually with a length from , a width between , and a thickness from .

Sectors and use

Tannery sector

In the tannery sector the splitting band knife allows to divide/split leather and textile in its thickness. The final products of this operation are Split and Grain (internal and external parts) of the leather.

Blades can be used to split every kind of material which has to be split in the thickness:

 leather
 fur
 non-woven material
 velvet

In the tannery sector, splitting band knives can be used in following working: wet blue, lime, dry, wet white and other tannings.

The blades which are mostly used in this sector are rectified on both edge and surfaces in order to guarantee the best splitting, that means a constance in the thickness of the leather  that is produced/split (rectification of surfaces), and also to guarantee the maximum linearity during the splitting process ( back edge); the blade must run as stable as possible without oscillations at all, which could create defects on the leather. Moreover, blades are used to be provided pre-bevelled in order to save time to start the blade running up once it is fitted on the splitting machine.

Rubber, cork and foam sectors
In the fields of rubber and cork, splitting band knives can be used on every kind of material that needs to be split in the thickness such as:

 rubber (except vulcanized rubbers) 
 cork
 foam

In this sector blades can be used according to their application, to the splitting machine, to the material and to the cut/split precision required by the final product.

Shoes and leather goods sectors

In the production linked to shoes and leather goods, the splitting band knives allow to divide/split and equalize or “reduce” the leather in the thickness in order to improve the quality of the finished product.

The final product of this working, equalization or “reduction” is a leather ready to become a shoe or leather goods (for example bags, wallets, belts, etc..) The hides used in this sectors are always finished leathers and in dry.

In this field, splitting band knives can be used on every kind of material that needs to be split in the thickness such as:
 
 leather 
 textiles – linings
 rubber – insoles
 cardboard components

The blades which are mostly used in this sector are rectified on both edge and surfaces in order to guarantee the best splitting, that means a constance in the thickness of the leather  that is produced/split (rectification of surfaces), and also to guarantee the maximum linearity during the splitting process ( back edge); the blade must run as stable as possible without oscillations at all, which could create defects on the leather. Moreover, blades are used to be provided pre-bevelled in order to save time to start the blade running up once it is fitted on the splitting machine.

Paper sector

The splitting band knife can be used also in paper sector and allows to divide/to split the material in the thickness, for example paper reels (from toilet paper to the reels for industrial use, paper towel rolls for domestic use, etc..)

In this production, the final product obtained by the splitting is:

 paper for industrial sector: big rolls, reels, etc.. for hygienic uses: handkerchiefs, toilet paper, kitchen rolls

In this sector blades can be used according to their application, to the splitting machine, to the material and to the cut/split precision required by the final product

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 . 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  wide for foam converting is popular, for leather goods  wide blade is popular,  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 . 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  for  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 non powered 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
 1808 W. Newberry patent No. 3105 London, including "machinery for ... splitting skins", 
 1854 J.F. Flanders and J.A. Marden with a patent for a bandknife machine,
 1912: Foundation of blade manufacturer Rudolf Alber,
Before WW II: several machinery brands on the market: Turner, Clasen, USM, BMD,
 2011: Known Polish pneumatic lifting table manufacturer REXEL started producing Vertical Band knife machines. At the moment there are models: R1250, R1150, R1000, R750, R500 (The number e.g. 1000 is the arm length in cm).

Images

References

Knives
Power tools