# Cutting Force When Machining Hardened Steel and the Surface Roughness Achieved
## 3 Results
### Evaluation of the Surface Quality of the Functional Area
#### 3.3.2 Evaluation of the Surface Quality of the Functional Area by the Non-Contact Method  
The evaluation of the surface quality of the functional surface by the non-contact method was carried out using the Alicona instrument for samples 5 and 6, where the best results were obtained, and for sample 8, where the worst results were obtained. For relevance, sample 12 with the highest values of cutting conditions was also assessed. The results are shown in Table 9.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Sample** & \(\mathbf{v_{c}}\) & \(\mathbf{f}\) & \(\mathbf{a_{p}}\) & \(\mathbf{\mathrm{Ra}}\) & \(\mathbf{\mathrm{Rz}}\) & \(\mathbf{\mathrm{Rmr}}\) \\
**No.** & **(\(\mathbf{\mathrm{m}}\cdot\mathbf{\mathrm{min}}^{-1}\))** & **(\(\mathbf{\mathrm{m}}\cdot\mathbf{\mathrm{rev}}^{-1}\))** & **(\(\mathbf{\mathrm{mm}}\))** & **(\(\mathbf{\mathrm{\mu}}\))** & **(\(\mathbf{\mathrm{\mu}}\))** & **(\(\mathbf{\mathrm{\%}}\))** \\ \hline
1 & & 0.05 & 0.2 & 0.38 & 2.27 & 48.9 \\
2 & 130 & 0.05 & 0.35 & 0.34 & 2.17 & 48.7 \\
3 & & 0.1 & 0.2 & 0.36 & 2.17 & 46.7 \\
4 & & 0.1 & 0.35 & 0.37 & 2.23 & 47.7 \\ \hline
5 & & 0.05 & 0.2 & 0.27 & 1.63 & 52.6 \\
6 & & 0.05 & 0.35 & 0.23 & 1.43 & 49.4 \\
7 & & 0.1 & 0.2 & 0.35 & 2.17 & 48.8 \\
8 & & 0.1 & 0.35 & 0.48 & 2.87 & 47.9 \\ \hline
9 & & 0.05 & 0.2 & 0.28 & 1.73 & 51.1 \\
10 & & 0.05 & 0.35 & 0.36 & 2.07 & 50 \\
11 & & 0.1 & 0.2 & 0.3 & 1.9 & 50.7 \\
12 & & 0.1 & 0.35 & 0.3 & 1.93 & 50.4 \\ \hline \hline \end{tabular}
\end{table}
Table 7: Values of selected surface quality parameters obtained under the specified cutting conditions.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Sample** & & **Ra** & & **Ra** & **Standard** \\
**No.** & & **Measured (\(\mathbf{\mathrm{\mu}}\)m)** & & **Average (\(\mathbf{\mathrm{\mu}}\)m)** & **Deviation** \\ \hline
1 & 0.41 & 0.40 & 0.32 & 0.38 & 0.049 \\
2 & 0.33 & 0.39 & 0.30 & 0.34 & 0.046 \\
3 & 0.34 & 0.33 & 0.41 & 0.36 & 0.044 \\
4 & 0.38 & 0.37 & 0.37 & 0.37 & 0.006 \\
5 & 0.27 & 0.27 & 0.28 & 0.27 & 0.006 \\
6 & 0  
The meanings of the abbreviations are as follows, according to ISO4287:  
Ra--Average arithmetic deviation of the profile;  
Rz--Maximum profile height;  
Rmr--Mutual material ratio for (Mr = 50%, an offset R\(\c\) = 0.1 \(\upmu\)m);  
and according to ISO13565:  
Rk--Core roughness depth, height of the core material;  
Rpk--Reduced peak height, mean height of the peaks above the core material;  
Rvk--Reduced valley height, mean depth of the valleys below the core material;  
Rmr1--Peak material component, the proportion of peaks above the core material;  
Rmr2--Peak material component, the fraction of the surface which will carry the load.  
The comparison of Ra and Rz values in the touch and non-contact methods shows almost the same values for samples 5 and 6, while better values were measured in samples 8 and 12 by the non-contact method. In the following Figures 13-18 detailed representations of the progression of the individual variables for the samples are given.  
Figure 16: Profile measurement part 12: Ra 0.196 \(\upmu\)m, Rz 1.302 \(\upmu\)m.  
Figure 17: Profile measurement display of the surface: (**a**) part 5, (**b**) part 6, (**c**) part 8, (**d**) part 12.