This paper presents theoretical and experimental research on the process of calibrating corn seeds using a specialized equipment with cylindrical sieves, studying the influence of process parameters and corn seed particularities on the quality of the calibration work. The research took into consideration corn seed characteristics, namely, their dimensions (length, width, and thickness) and weight, determining the influence of process parameters—the contact point between the seed and the cylindrical sieve, the influence of the length of the sieve, and the sieve’s revolution speed on the separation process. The experiments for determining the influence of these parameters on the calibration process were conducted on a calibrating equipment with cylindrical sieves using three different corn hybrids. It was noticed from the experiments that, overall, the revolution speed had the most important effect on the calibration process, with sieve length also affecting the process, but to a lesser degree. Seed calibration efficiency was best at the smallest revolution speed (33 rot/min) and decreased when the revolution speed increased up to 49 rot/min for all corn hybrids tested. The number of calibrated seeds decreased in the second part of the cylindrical sieve. Seed thickness influenced the process, in the respect that seeds smaller than 4.8 mm passed through the first third of the sieve and those with a thickness between 4.8 and 5 mm passed through the other two thirds of the sieve length.