TPT March 2018

T E CHNOLOG Y

The best circular saw blade tooth geometry By Willy Goellner, chairman Goellner, Inc/Engineering R&D

advantage was that each single tooth split the chip and stabilised each tooth by side guiding, improving the tool life. Every tooth is guided in the slot, compared to every other with the triple chip geometry. This cutting process is better for interrupted cuts, because more teeth are guiding on their sides, reducing vibrations and improving tool life. Notch grind geometry also increases cut rates, making it the preferred geometry for billet sawing as well. Surprisingly, the notch has no negative cutting effect. Higher cutting rates, however, require a more rigid saw with more power, so not every saw will cut efficiently with notch grind saw blades. With a rigid carbide saw, the notch grind geometry allows you to cut the entire range of solid and structural profiles at faster rates and with better tool life. Advanced Machine & Engineering – USA Website: www.amsaw.com

geometries developed to split the chip: ‘triple chip’ and ‘notch grind’. Triple chip geometry splits the chip into three parts. The first tooth is about 0.013" higher than the second tooth and cuts the centre of the slot, and the second tooth cuts the remaining two sides, which creates three chips. The triple chip geometry allows a pair of teeth to cut the width of the slot, but only the secondary teeth guide the blade into the slot. This geometry has been successful in cutting solid steel billets because it reduces vibration and creates a quieter cut. The newer notch grind geometry was developed by Horst Döpke at Braunschweig University for cutting tubing, pipes or profiles. The chip of each tooth is split by a groove on the cutting face. A similar geometry was developed and patented in 1984 by Goellner for Speedcut – now AMSAW – to cut solid billets at a higher cutting rate. The

CIRCULAR saw blades with brazed carbide teeth were first used on plate saws to cut steel plates at Ingersoll Milling Machine Co in Illinois, USA, in 1963. The basic geometry with positive cutting angle of the carbide teeth was taken from aluminium circular saw blades, but the tool life was not economical for cutting steel billets. In the late 1960s, the University of Braunschweig (Germany) developed a new geometry for cutting steel with 18° negative cutting angles and chamfered all of the cutting edges to avoid sharp corners to prevent breakage. This geometry was successfully applied on the first billet saw in 1969, developed by Advanced Machine & Engineering Co (AME). The heat from the cutting process, especially using negative cutting angles when cutting steel, transfers to the chip, causing it to expand and jam in the slot. This can be prevented by splitting the chip. There are two common tooth

Integrated solutions BM GROUP is an Italian industrial company, operating worldwide as a supplier of advanced automation equipment and customised robotic solutions. Polytec has been part of BM Group since 2012. Thanks to experience acquired in the steel sector as a supplier of advanced automation systems, it focuses on the production of highly technological robotic cells for the steel and tube and pipe sector. Knowledge of the steelmaking process, together with a constant investment in R&D, have been keys to understanding the changing needs of steelmakers. Polytec has developed a range of more than 15 robotic cells that integrate the steelmaking process from the furnace to the finishing mills, long and flat as well as tube and pipe. Each solution is manufactured to exact customer requirements and is tested at Polytec’s workshop.

BM Group – Italy Website: www.bmgroup.com

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MARCH 2018