Vibration has always been an inherent and unwanted characteristic of metal sawing, a trait machine and blade manufacturers have been working to mitigate for decades. Compounding the challenge is the need in today’s market for cutting harder, larger-sized materials. Machine manufacturers have developed damping devices, while blade companies have focused on varied-pitch blades and special tooth designs to reduce band saw vibration. Though these attempts have shown limited success in increasing blade life and cutting rates, vibration continues to be a problem. In response, Amada Cutting Technologies Inc., La Mirada, Calf., developed Double Pulse Cutting, designed to maximize productivity and blade performance by reducing vibration and cutting resistance. Double Pulse Cutting employs a totally new metal band sawing mechanism, developed in conjunction with a major motor manufacturer. The partnership produced a technologically advanced pulse drive motor that virtually eliminates vibration, according to Amada.

VIBRATION Figure 1 – When metal is cut using conventional sawing technology, two types of vibration occur: frictional vibration and tooth tip vibration. As the number of cut pieces increases, the sound pressure level increases. This noise level is proportional to the wavelengths of the vibrations. Therefore, eliminating these vibrations will reduce cutting noise and increase cutting efficiency. As the number of cut pieces increases, the sound pressure level also increases, indicating that the noise level is proportional to the wavelengths of vibrations. Therefore, eliminating these vibrations will reduce cutting noise and increase cutting efficiency. Controlling tooth tip vibration is the key to producing quality surface finishes and increased tool life. Tooth tip vibration causes excessive tooth chipping, and chipped teeth produce an unacceptable surface finish. As illustrated in Figure 2, pulse cutting reduces chipping and improves the blade life and quality of the cut, compared with conventional cutting.

ADVANTAGES OF PULSE CUTTING Figure 2 – In conventional cutting, tip vibration causes excessive chipping, and chipped teeth produce a poor quality cut. Pulse cutting controls tip vibration, reducing chipping and improving the surface finish and blade life. Understanding these concepts, Double Pulse Cutting Technology was developed to eliminate vibrations, preventing premature blade tooth wear, material damage and undesirable noise levels while increasing productivity. In metal sawing, two forces are required for efficient cutting: longitudinal force and penetration force (see Figure 3). The function of the dual pulse is to keep both forces at a constant. By controlling these forces, high cutting rates and minimal noise levels can be achieved.

HOW IT WORKS Figure 3 – In metal sawing, two forces are required for efficient cutting: longitudinal force and penetration force. Figure 4 shows the pulse cutting effect analysis in the longitudinal direction.

Figure 4 – Pulse cutting technology, driven by a special high-output servomotor, sends out vibration-dampening pulses to the blade. By canceling out the blade vibrations, the pulses reduce cutting resistance and tooth chipping for increased blade life and improved surface finishes. In conventional cutting, the rotation of the band saw’s drive wheel creates consistent blade speed. This creates frictional vibration and generates high amounts of tooth tip vibration. In pulse cutting, the drive wheel is controlled by a special high-output servomotor. This servomotor assures constant blade speed control of the longitudinal force and eliminates the vibration at the cutting area. In short, the servo direct drive wheel sends another vibration to cancel out the frictional vibration to the blade. This is the first pulse. The second pulse enhances penetration force by sending vibration-dampening pulses to the blade. These mechanically induced pulses are created by a very precise set of multi-lobe cams mounted above the blade, both spinning at a predetermined RPM to strike the blade at exactly the same time, producing successive pulses that assure proper damping. These successive pulses reduce cutting resistance and tooth chipping for increased blade life and improved surface finishes.

Amada Cutting Technologies, Inc., La Mirada, Calf., sells and distributes band saw machines, bi-metal blades and parts. For more information, visit www.amadabandsaw.com

Posted with permission of Metal Center News.

© 2008 Amada Cutting Technologies, Inc. All rights reserved.