Fingernail effect
The fingernail effect describes the loss of performance of rotating flap tools at excessive speed.
The result is reduced cutting performance, decreased material removal, and insufficient edge rounding.
Origin of the fingernail effect
The fingernail effect occurs in rotating lamellar tools due to excessively high rotational speeds.
Increasing centrifugal forces stiffen the lamellae and reduce their ability to adapt to the workpiece edge. This makes the tool engagement unstable, reduces the cutting effect, and impairs material removal and edge rounding.Factors influencing the fingernail effect
- speed
- tool assembly
- process parameters
- material properties
Impact on subsequent processes
An unstable tool engagement reduces the reproducibility of edge processing and affects the quality of subsequent processes.
This results in uneven transitions between surface and edge, especially when rounding edges.
Potential impacts on quality
- reduced removal rate
- insufficient edge rounding
- unstable tool engagement
- decreasing cutting effect
- uneven tool wear
- reduced process stability
Difference between stable and unstable tool engagement
With stable process control, the lamellae actively engage the workpiece edge and produce reproducible rounding.
In contrast, with the fingernail effect, the lamellae become increasingly stiff. The tool intervention becomes superficial and unstable.
Typical differences
- Stable tool engagement: active cutting action at the workpiece edge
- Fingernail effect: superficial contact through stiffened lamellae
- Stable tool engagement: uniform edge rounding
- Fingernail effect: insufficient and unstable rounding
- Stable tool engagement: controlled material removal
- Fingernail effect: decreased material removal and unproductive wear
Edge rounding as a process step
In the deburring and edge rounding process step, rotating lamellar tools are used to remove primary and secondary burrs and to create a reproducible radius-like transition between surface and edge.
FAQ
What is the fingernail effect during deburring?
The fingernail effect describes the loss of power in rotating lamellar tools at excessively high speeds and reduced cutting effect during deburring and edge rounding.
How can the fingernail effect be avoided?
The fingernail effect is avoided through a coordinated rotational speed, stable cutting speed and flexible lamellar tools.