Steadfastness

According to DIN  6583, the stability refers to the ability of an active pair ( workpiece and tool ) to withstand certain machining processes .

The tool life is influenced by the cutting edge retention of the tool, the machinability of the material and the tool life conditions , i. H. the conditions that affect the machining process.

Stand conditions

The most important stand conditions are:

• Workpiece geometry and material
• Tool geometry and material ( cutting material )
• Cutting speed .

Further stand conditions are

• the static and dynamic rigidity of the machine tool
• the kinematics of the machining process
• the cutting conditions
• the environment
  • the amount of cooling lubricant
  • the thermal boundary conditions during processing .

Stand sizes

Stand sizes are according to DIN 6583

• the service life  (most important) ${\displaystyle T}$
• the tool life  ${\displaystyle L}$
• the standing quantity  or the standing volume , ${\displaystyle N}$  ${\displaystyle V}$

which are achieved under certain standing conditions until a certain standing criterion occurs. The various stand sizes are therefore always assigned associated criteria and conditions.

Wear parameters are often used as standing criteria . Wear on machining tools is usually the width of wear measured, which is a measure for the free surfaces is wear, and with the scour depth, which is a measure for the crater wear on the rake face is. For example, this means that the service life until a wear mark width of 0.2 mm is reached at a cutting speed of 200 m / min is equal to 60 minutes. ${\displaystyle T_{VB0,2;vc200}=60\ min}$ ${\displaystyle VB}$

The following values ​​are usually used as permissible wear mark widths:

Wear mark width	High speed steel / carbide	Cutting ceramics
Roughing	0.8 to 1.0 mm	0.3 mm
Finishing	0.2 to 0.4 mm	0.3 mm

Other standing criteria besides wear are

• the cutting force
• the cutting performance
• the surface roughness on the workpiece
• the chip shape
• the chip temperature.

Relationship between the stand sizes

In some processes it is common to specify the tool life, which depends on the tool life . ${\displaystyle L}$ ${\displaystyle T}$

When drilling and milling , the tool life is measured in the feed direction:

${\displaystyle L_{f}=T\cdot f\cdot n}$

With:

• ${\displaystyle L_{f}}$- Tool life in feed direction (Engl. Feed )
• ${\displaystyle f}$- feed
• ${\displaystyle n}$- speed ,

when planing and broaching in the cutting direction:

${\displaystyle L_{c}=T\cdot v_{c}}$

With

• ${\displaystyle L_{c}}$- Tool life in the cutting direction (English cut )
• ${\displaystyle v_{c}}$ - cutting speed.

Sometimes the tool life is also given, which also depends on the tool life: ${\displaystyle N}$

${\displaystyle N={\frac {T}{t_{h}}}}$

With

• ${\displaystyle t_{H}}$- prime time .

In addition to the service life, the stability can generally also be specified by the conditions or criteria:

${\displaystyle v_{cT15;VB0,2}=200{\frac {m}{min}}}$

Here the cutting speed of a certain tool, at which a wear mark width of 0.2 mm is reached within 15 minutes, is equal to 200 m / min.

The value

${\displaystyle F_{cap2;N500}}$

however, indicates the cutting force for a cutting depth of 2 mm and a tool life of N = 500. ${\displaystyle a_{p}}$

See also

• Tool life (machining)
• Wear (cutting)

Individual evidence

1. ^ Fritz Klocke, Wilfried König: Manufacturing process 1. 8th edition. 2008, p. 259.
2. ↑ ^{a b c d} Fritz Klocke, Wilfried König: Manufacturing process. 8th edition. Springer, 2008, p. 259 f.
3. ^ Alfred Herbert Fritz, Günter Schulze: Manufacturing technology. 11th edition. Springer, 2015, p. 289 f.
4. ↑ Berend Denkena, Hans Kurt Tönshoff: Spanen - basic. 3. Edition. Springer, 2011, p. 149.
5. ↑ Herbert Schönherr: Machining production. Oldenbourg, 2002, p. 48.