## 3 Results
Series 1 of the experiment conducted at minimum laser power, with maximum cutting speed, has a higher cutting width, under the conditions of using the auxiliary gas at average to maximum values;
3. Series 2 which uses an average power of 5000 W achieves a good cut with a qualitative aspect, without structural defect of the parts. The cutting width reaches the lowest value in six experimental cases. The combination of medium power, low pressure and medium speed indicates the best result of the cutting width. In addition, the average power combined with the average pressure and any value of the cutting speed, indicates a cutting width of 0.30 mm;
4. If the laser power increases, it causes an increased energy density of the laser beam. The heat absorption in the steel sheet increases and the melt increases its volume, which determines a large cutting width;
5. Series 3 indicates a generally increased cutting width involving high consumption and costs. The cutting width increases with the evolution of laser power up to 5100 W;
6. The cutting width decreases if a laser spot with moderate energy is used. This causes a local heat that melts a very small volume of material and after a very short time it dissipates quickly through the material;If the cutting speed decreases, the time of interaction between the spot and the material increases, having as an effect a longer irradiation of the material, high heat absorption, increased melted volume and finally, the cutting width deteriorates;
8. If the cutting speed is increased, the spot-part interaction time decreases, resulting in reduced heat absorption of the H400 plate and a decrease in the cutting width;
9. If low assist gas pressure values are used, the cutting width is affected. From the calculations, a cutting width of 0.37 mm is obtained, a good result that falls within the limits of the experimental data. Next, the individual influence of laser power and gas pressure on Kerf was studied. The graphs are built to find the dependence of the cutting width on the laser power. Series 1 was run at 4900 W in three references, 5000 W in three experiments and 5100 W in three cases, at the same time with the low pressure of 0.45 bar kept constant. Nine values for the cutting width resulted. The coefficient of determination R\({}^{2}\) = 0.33 is low. For series 2, the procedure was similar, slightly increasing the gas pressure to 0.50 bar (Figure 4). \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline
**Part No. ** & \multicolumn{4}{c}{**Observations on the Cut Parts**} & \multicolumn{4}{c}{**Input Parameters**} & \multicolumn{2}{c}{**Output**} \\  & \multicolumn{4}{c}{} & \multicolumn{4}{c}{} & \multicolumn{4}{c}{**Parameter**} \\ \hline \multirow{4}{*}{Clean cut} & \multicolumn{3}{c}{ \begin{tabular}{c} Melt deposition \\ on the bottom \\ edge at the laser exit from \\ the material \\ \end{tabular}  } & \multirow{2}{*}{ \begin{tabular}{c} Multiple \\ cities \\ \end{tabular}  } & \multirow{2}{*}{ \begin{tabular}{c} Deep \\ striations \\ \end{tabular}  } & \multirow{2}{*}{ \begin{tabular}{c} Oblique chamfer \\ over the grooves \\ when changing the cutting direction \\ \end{tabular}  } & \multirow{2}{*}{ \begin{tabular}{c} Laser \\ over the grooves \\ when changing the cutting direction \\ \end{tabular}  } & \multirow{2}{*}{ \begin{tabular}{c} Gas \\ power \\ (W) \\ \end{tabular}  } & \multirow{2}{*}{\ \begin{tabular}{c} Cutting \\ pressure \\ (bar) \\ (bar) \\ \end{tabular}  } & \multirow{2}{*}{ \begin{tabular}{c} Cutting \\ speed \\ (mm/min) \\ \end{tabular}  } \\ \hline
1 & \(\surd\) & & & & 4900 & 0.45 & 1700 & 0.40 \\ \hline
2 & & \(\surd\) & \(\surd\) & & 4900 & 0.45 & 1800 & 0.30 \\ \hline
3 & & \(\surd\) & \(\surd\) & & 4900 & 0.45 & 1900 & 0.4  
The Pearson coefficient R\({}^{2}\) = 0.66 shows that the cutting width depends on 66% laser power.