## 3 Results and Discussion
### Optimal Parameter Settings of the Investigated Process  
It is desirable to minimize the subsequent post processing due to minimizing the cost of the cutting process by the energy beam. It is possible to achieve cost minimization by optimally setting the parameters of the investigated process, in order to achieve the required values of process responses based on a mathematical-statistical model. The goal is to reach a minimum value in the case of WKU*, WHAZU*, WKD*, WHAZD*, and B*, and in the case of WKR*, the goal is to achieve the value 1 and at the same time to find the optimal values of the factors P, V, and AR. There are six polynomial functionsbased on Table 5, five of which need to be minimized and one of which needs to be normalized, i.e., needs to be equal to one:  
\[\textbf{WKU*}=1.96353+0.00695\cdot\mathrm{V^{2}}+0.08847\cdot\mathrm{P^{*}V}+0.0 0032\cdot\mathrm{AR^{*}V}-0.00745\cdot\mathrm{AR^{*}P}+0.00526\cdot\mathrm{AR^{2}} \\ -0.25323\cdot\mathrm{V}-0.29207\cdot\mathrm{P}-0.05862\cdot\mathrm{AR} =\textbf{min},\]  
\[\textbf{WHAZU*}=0.23073-0.00193\cdot\mathrm{V^{2}}-0.02749\cdot\mathrm{P^{*}V}- 0.00108\cdot\mathrm{AR^{*}V}+0.00257\cdot\mathrm{AR^{*}P}-0.00142\cdot\mathrm{AR^{ 2}}\\ +0.08067\cdot\mathrm{V}+0.19104\cdot\mathrm{P}+0.02398\cdot\mathrm{AR} =\textbf{min},\]  
\[\textbf{WKD*}=-0.13999-0.00489\cdot\mathrm{V^{2}}-0.02015\cdot\mathrm{P^{*}V}- 0.00208\cdot\mathrm{AR^{*}V}-0.05651\cdot\mathrm{AR^{*}P}+0.00034\cdot\mathrm{AR^{ 2}}\\ +0.03693\cdot\mathrm{V}+0.81739\cdot\mathrm{P}+0.06392\cdot\mathrm{AR }=\textbf{min},\]  
\[\textbf{WHAZD*}=-0.78817+0.00099\cdot\mathrm{V^{2}}+0.01778\cdot\mathrm{P^{*}V}+ 0.00121\cdot\mathrm{AR^{*}V}+0.02135\cdot\mathrm{AR^{*}P}-0.00349\cdot\mathrm{ AR^{2}}\\ -0.05375\cdot\mathrm{V}+0.00574\cdot\mathrm{P}+0.0120  
In case we need to optimize only one parameter separately, we can achieve even better results, since, in the case of joint optimization, the values are related to each other. The obtained values of separate optimization for all parameters are given in Table 7. In practice, in the case of laser wood cutting, it is not always necessary to achieve the optimized quality of all parameters at the same time. In some cases, with specific requirements for the cutting zone created in laser cutting, optimization of the cutting zone for only one parameter is needed, e.g., the maximum surface flatness is required for subsequent gluing (WKR = 1); in case of increased requirements for the tensile shear strength of the glue joint, minimization of charring is required (B = min); and in the case of subsequent edging and the requirement of one viewing area, minimization of the HAZ is required (WHAZxU alebo WHAZxD = min). In some cases, the perfect surface is counterproductive (in the case of adhesion of the glue, etc.). Alternatively, there is a requirement to combine the optimization of two parameters, e.g., at subsequent edging and the requirement of two viewing surfaces (WHAZxU and WHAZxD = min). These requirements are applied, especially in the case of wood composites (plywood, particleboard, fiberboard, etc.), in the production of furniture elements. In practice, in most cases, the second optimization is more important due to the above reasons.  
The obtained results show a high correlation with experimentally measured results, despite the difficulties largely resulting from the anisotropy of spruce wood, and at the same time, they are comparable with the results of authors investigating cutting by a radiation beam generated by a CO\({}_{2}\) laser for other wood species, as well as wood composites [(53; 65; 81; 82; 83)].