## 4 Experimental Measurements
### Abrasion with the Use of Lubricating CX80 Copper Grease  
This is an anti-adhesive, multi-purpose product for use under the most difficult conditions and within a high temperature range from \(-30\) to \(1200\ ^{\circ}\)C. It ensures excellent lubrication, safeguards against attrition, corrosion, and high temperatures, and has a wide temperature range (\(-30\) to \(+1200\ ^{\circ}\)C). Meanwhile, its density is \(0.9\ \mathrm{g/cm^{3}}\)[18].  
It is compatible with screws and nuts, threads and all connected surfaces, fittings, spark plugs, wheel and brake discs, battery joints, port installations, revolving discs, highly stressed bearings of all kinds, elements in the industrial and construction fields, other elements of industrial systems, construction, and agricultural and motor vehicles [19; 20]. The measured values with copper grease can be seen in Table 4 and Figure 11.  
The calculated coefficients of friction \(f^{\prime}\) for the individual tightening torques in abrasion with lubricating copper grease CX80 are as follows:  
\[\begin{split} f_{\text{C1}}=\frac{2\pi\cdot M_{\text{TCI}}-F_{ \text{C01}}\cdot s}{\pi\cdot F_{\text{C01}}\cdot d_{s}}=\frac{2\pi\cdot 4\ Nm-1076 4\ N\cdot 0.0025\ m}{\pi\cdot 10764\ N\cdot 0.018376\ m}=0.3611\\ f_{\text{C2}}=\frac{2\pi\cdot M_{\text{TCI}}-F_{\text{C02}}\cdot s }{\pi\cdot F_{\text{C02}}\cdot d_{s}}=\frac{2\pi\cdot 8\ Nm-21543\ N\cdot 0.0025\ m}{\pi\cdot 25143\ N\cdot 0.018376\ m}=0.3608\\ f_{\text{C3}}=\frac{2\pi\cdot M_{\text{TCI}}-F_{\text{C03}}\cdot s }{\pi\cdot F_{\text{C03}}\cdot d_{s}}=\frac{2\pi\cdot 12\ Nm-3236.9\ N\cdot 0.0025\ m}{\pi\cdot 32 63\ N\cdot 0.018376\ m}=0.3601\\ f_{\text{C4}}=\frac{2\pi\cdot M_{\text{TCI}}-F_{\text{C04}}\cdot s }{\pi\cdot F_{\text{C04}}\cdot d_{s}}=\frac{2\pi\cdot 16\ Nm-4315.7\ N\cdot 0.0025\ m}{\pi\cdot 4315.7\ N\cdot 0.018376\ m}=0.3601\\ f_{\text{C5}}=\frac{2\pi\cdot M_{\text{TCI}}-F_{\text{C05}}\cdot s }{\pi\cdot F_{\text{C05}}\cdot d_{s}}=\frac{2\pi\cdot 20\ Nm-5318.6\ N\cdot 0.0025\ m}{\pi\cdot 53 8.6\ N\cdot 0.018376\ m}=0.3659\\ \end{split} \tag{15}\]  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**No. of Measurements** & **1** & **2** & **3** & **4** & **5** \\ \hline Loading—lightening torque \(M_{\text{TC}}\) (\(Nm\)) & 4.0 & 8.0 & 12.0 & 16.0 & 20.0 \\ \hline Emerging axial force \(F_{\text{OC}}\) (\(N\)) & 1076.4 & 2154.3 & 3236.9 & 4315.7 & 5318.6 \\ \end{tabular}
\end{table}
Table 4: Values determined via measurement with lubricant CX80—copper grease.  
The actual coefficients of friction \(f\) for the individual tightening torques in abrasion with lubricating copper grease CX80 are as follows:  
\[\begin{split} f_{\text{C1}}&=f{f_{\text{C1}}}\cdot \cos\frac{\pi}{2}=0.3611\cdot\cos\frac{6\omega^{2}}{2}=0.2339\\ f_{\text{C2}}&=f{f_{\text{C2}}}\cdot\cos\frac{\pi}{2}=0. 3608\cdot\cos\frac{6\omega^{2}}{2}=0.2337\\ f_{\text{C3}}&=f{f_{\text{C3}}}\cdot\cos\frac{\pi}{2}=0. 3601\cdot\cos\frac{6\omega^{2}}{2}=0.2333\\ f_{\text{C4}}&=f{f_{\text{C4}}}\cdot\cos\frac{\pi}{2}=0. 3601\cdot\cos\frac{6\omega^{2}}{2}=0.2333\\ f_{\text{C5}}&=f{f_{\text{C5}}}\cdot\cos\frac{\pi}{2}=0. 3659\cdot\cos\frac{6\omega^{2}}{2}=0.2370\\ \end{split} \tag{16}\]