Silent Tools will always be able to stretch further than similar solid tools.
 A change in application leads to a resetting of the limits. A solid boring bar will perform adequately in general turning out to 4 times its diameter without vibrations. In more difficult applications, such as internal threading and grooving, vibrations will start at an overhang between 2 and 3 times the bar diameter.
In comparison, our most highly developed bars stretch 15 times beyond their own diameter.
This page shows you how you can stretch the limits using your existing tools. If your old tools cannot handle the new limits well enough, more than 60 different damped bars and adapters are listed in the Turning Tools Catalogues from Sandvik Coromant. Our R&D department can also help you make a special tool.
A vibration is a variable deflection.
No deflection = no vibration
Vibrations in a cutting tool are triggered and maintained by a dynamic cutting force. Even in a continuous cut, the cutting force will have small rapid changes in both size and direction around a certain average. The keys to eliminate vibrations are the following:
Increase static stiffness - Reduce cutting forces - Increase dynamic stiffness
 Increase static stiffness ; Choose the bar with maximum diameter, and minimum length.
Special bars can be shape optimized (tapered, elliptic) to utilize all available space in the workpiece. They can even be reinforced with materials that are stiffer than steel. 
One bar at varying overhang, taking a constant cutting force ; Increased length from 4 to 10 times bar diameter, will give a 16 times larger deflection.
A further extension from 10 to 12 times bar diameter, gives another 70 % increase in deflection from the same cutting force.
 Two bars with the same length, taking the same cutting force ; Changing from 25 mm diameter to 32 mm diameter reduces deflection with 62%.
Cut with sharp edges to minimize the force required to do the intended cut.
An entering angle close to 90° will direct as much as possible of your feed force in the axial direction of the bar. (Note: This is not effective unless nose radius is smaller than the radial depth of the cut)
If there is no vibration in the radial direction the boring bar will make a good surface even with small vibrations in the tangential direction.  Reduce force variations ;
The smallest insert point angle you can accept will give good clearance of a trailing surface, and small chip area variations if the tool starts vibrating in a radial direction.
Reduced weight on cutting units will minimize the kinetic energy in a possible vibration. This will make it easier for the tool to dampen possible vibrations, and thus stretch the maximum overhang for both solid and damped tools.
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