Sandvik Coromant Silent tools - application guide - Manual (Page 10)

8
m
k
f
π 2
1
=
1. Introduction
In summary:
1. Reduce cutting forces by choosing the right cutting tool and
insert
2. Minimize deflection by increasing the static stiffness through
largest possible shank diameter and minumum length
3. Reduced weight on cutting units will minimize the kinetic energy
in a potential vibration
4. When extending modular tools, build large diameters
5. For engineered products, consider optimized shapes and
material reinforcements
Vibration basics
Mechanical structures tend to vibrate with one or more resonance
frequencies determined by geometry and material. Each resonance
frequency corresponds to a ”vibration mode”. The dampening deter-
mines how fast the vibration settles after being triggered. With increased
deflection, the energy in the oscillation increases.
The force variations in machining will trigger the self-induced vibration
at the natural frequencies of the machine tool. Once the vibration is
triggered, it will feed on the forced vibration and grow larger and larger,
unless you can reduce the force variations.
Variations in machining forces can depend on a number of things, and if
nothing is done to reduce the cutting forces, the vibration will increase.
• Chip segmenting process
• Interrupted cut
• Inclusions in the material
• Ovality in the workpiece
• Formation of built-up edge
k = spring constant
m = object mass
f = vibration frequenzy
δ = tool deflection
F = force on the tool