Actual surface hardness describes the measured hardness of a material surface after manufacturing, heat treatment, or surface treatment. It indicates how resistant the surface is to penetration, wear, or mechanical stress.
Surface hardness particularly influences:
- Wear resistance of the spindle, nut, or balls
- Service life and load capacity of thread drives
- Friction and sliding properties
- Compressive strength of the contact surfaces
Influencing factors
- Material: steel, bronze, aluminum, plastic
- Heat treatment: hardening, tempering, nitriding
- Surface treatment: grinding, induction heating, coatings
- Manufacturing tolerances: roughness, surface profile, smoothing
The actual surface hardness can deviate from nominal or theoretical values and is therefore usually measured (e.g., using Rockwell, Vickers, or Brinell hardness testing).
Practical relevance
- Critical for ball screws: raceway hardness determines contact pressure and service life
- Decisive for friction and wear in trapezoidal thread drives
- Basis for maintenance intervals, lubrication, and application limits