## 2 Modelling Background
### Materials and Equipment
ErgoTronic uses the data obtained from DensiTronic to precisely adjust the machine settings and controls the registers (print register, paper folding and cutting register, and print rub register). The control strips are additionally verified using a densitometer. In this study, controlled factors are defined as process parameters with predetermined values that are kept constant throughout the experiment. These parameters play a key role in ensuring the stability of the conditions and the reliability of the research results. They were regulated by precise measuring devices and control systems integrated into the printing machine. The controlled factors are:  
* \(X_{1}\) (paper temperature): defined at 22 \({}^{\circ}\)C, measured with a Dostmann P300W thermometer (i.e.,'sword'), to prevent dimensional deformation of the paper and maintain stability during the printing process. * \(X_{2}\) (paper humidity): defined at 45%, measured with a Dostmann P300W hygrometer (i.e.,'sword'). The humidity content of the paper is related to its hygroscopic nature and directly affects dimensional stability. * \(Z_{1}\) (dampening solution conductivity): defined at 1950 \(\upmu\)S/cm, a value chosen based on industry standards and previous research to ensure proper interaction of the solution with the paper surface. Conductivity is measured using a digital conductometer integrated into the ErgoTronic system, enabling continuous monitoring and precise control of conductivity throughout the process. This system automatically adjusts the dampening solution concentration to maintain the defined conductivity level, eliminating the possibility of variations and ensuring process stability. * \(Z_{2}\) (alcohol content in the dampening solution): defined at 8.5%, which is the optimal value according to industry standards for stable printing operation and proper distribution of the dampening solution on the roller surface. The alcohol content is measured using an alcohol concentration sensor integrated into the ErgoTronic system,enabling continuous monitoring and automatic regulation of the alcohol level. This system ensures that the alcohol content remains within the defined limits, preventing excessive evaporation or improper solution mixture, which could affect press stability and print quality. * \(Z_{3}\) (ink viscosity): defined at 160 mPa\(\cdot\)s for cyan, 180 mPa\(\cdot\)s for magenta, 140 mPa\(\cdot\)s for yellow and 150 mPa\(\cdot\)s for black, according to the specifications of factory-prepared inks used in the experiment. Since the viscosity of the ink is not regulated during the printing process, inks with factory-defined values were used, which comply with industry standards for offset printing. The stability of the ink viscosity was ensured by controlling the ink temperature (\(W_{1}\)) using the ErgoTronic system, minimizing viscosity changes caused by temperature fluctuations during the process. Maintaining proper viscosity was crucial for consistent ink application and uniform print quality across different halftone values. * \(Z_{4}\) (dampening solution hardness): defined at 9 dH, in line with industry standards for offset printing. This value ensures optimal stability of the dampening solution and prevents the formation of deposits on rollers and other parts of the press. The hardness of the solution was determined based on the chemical properties of the water used to prepare it and adjusted with appropriate additives before the printing process began. The hardness measurement was performed using the Hanna Instruments HI96735 digital photometer to analyze water hardness. After the initial setting, hardness was not regulated during printing, as this parameter remains stable throughout the process. The ErgoTronic system ensures precise regulation and maintenance of parameters throughout the printing process, eliminating the need for additional manual measurements.