# Surface hardness

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The surface hardness is given as Rockwell hardness HRC.  If the surface hardness is smaller than 58 HRC, a reduction in dynamic and static load capacity is taken into account according to [Harris](bibliography.md#harris_rumbarger_butterfield_dg03_2009). This reduction is only considered as long as the load capacity is calculated by the software. The reduction factor for dynamic load capacity is:

$C'=C\left(\frac{HRC}{58}\right)^3.6$

An input value for load capacity is not modified because of the hardness value. If a modification factor for dynamic load capacity or the permissible stress for static capacity is defined in material data, a reduction because of hardness is not considered.

The static safety factor is also affected by a reduced hardness. This is also done according to [Harris](bibliography.md#harris_rumbarger_butterfield_dg03_2009) using the factor fs:

$f_s = 1.5\left(\frac{HV}{800}\right)^2$(Ball bearings) or $f_s = 2\left(\frac{HV}{800}\right)^2$(roller bearings), with $f_s\leq 1$

For this formula, HV is calculated as HV = (223 \* HRC + 14500) / (100 - HRC) according to [Schlecht](bibliography.md#schlecht_bd2_2010).