**3. FE analysis of surface roughness model**

In order to analyse the influence of the surface asperities in wider range of roughness conditions of the tools and the materials, finite element (FE) analysis of the micro-deep drawing are carried out. To model from the microscopic roughness asperities to macroscopic material deformation behaviour, an advanced model with surface roughness is proposed.

Impact of Surface Topography of Tools and Materials in Micro-Sheet Metal Forming 119

Ironing

**A B C**

**A BC**

**Figure 9.** Distribution of equivalent plastic strain and close up images on part of (a) sliding with die

Ironing Sliding

**Smooth surface model Surface roughness model**

**0 100 200 300 400 500 Punch stroke /**μ**m**

**Figure 10.** Comparison between punch force-stroke curves of "surface roughness model" and

**Surface roughness model**

**Smooth surface model**

**x**

**x**

**(b)**

**y**

**0**

conventional "smooth surface model"

**5**

**10**

**15**

**20**

**Punch force /N**

**25**

**30**

**35**

**40**

**45**

corner and (b) ironing

**y**

**(a)** 

Sliding die radius

**Initial surface**
