A process for creating batches of unvulcanized rubber before mixing in a rubber mixer, including selecting at least one batch for mixing in the mixer, wherein each batch corresponds to a selection of rubber bales (A I, B I, C I) that each correspond to a nature of rubber composition (A, B, C) having predetermined characteristics, the method comprising the following steps: providing a supply station where uncured rubber bales (A I, B I, C I) are supplied from the corresponding rubber natures (A, B, C); selecting unvulcanized rubber bales (A I, B I, C I) from the rubber natures (A, B, C) and in a predetermined proportion corresponding to a batch selected at the supply station, wherein each batch comprises rubber types and grades from different suppliers, rubbers of different types from the same supplier, or a combination of the two; providing a cutting station comprising at least three cutting subassemblies (118, 118', 118") for cutting at least one bale (A I, B I, C I) into pieces (A IJ, B IJ. C IJ) and each cutting subassembly (118, 118', 118") is coupled with a respective linear actuator (120, 120', 120") that adjusts the position of a bale (A I, B I, C I) according to a recipe for the rubber mixture; providing a transport system that feeds the cutting subassemblies (118, 118', 118") and that transfers the bales (A I, B I, C I) and the pieces (A IJ, B IJ. C IJ) of rubber toward at least one mixer; weighing the bales (A I, B I, C I) to obtain the weight of the bales (A I, B I, Ci); comparing the weight of the bales (A I, B I, C I) with the required weight of the batch; and transporting the bales (A I, B I, C I) and the pieces (A IJ, B IJ. C IJ) between the supply station, via feed belt (14, 114) to the cutting station and the mixer according to a sequence determined by the equivalence between the required weight of the batch and (a) the weight of the bales (A I, B I, C I) or (b) a sum of the weight of the bales (A I, B I, C I) and a weight of the pieces (A IJ, B IJ. C IJ). providing a supply station where uncured rubber bales (A I, B I, C I) are supplied from the corresponding rubber natures (A, B, C); selecting unvulcanized rubber bales (A I, B I, C I) from the rubber natures (A, B, C) and in a predetermined proportion corresponding to a batch selected at the supply station, wherein each batch comprises rubber types and grades from different suppliers, rubbers of different types from the same supplier, or a combination of the two; providing a cutting station comprising at least three cutting subassemblies (118, 118', 118") for cutting at least one bale (A I, B I, C I) into pieces (A IJ, B IJ. C IJ) and each cutting subassembly (118, 118', 118") is coupled with a respective linear actuator (120, 120', 120") that adjusts the position of a bale (A I, B I, C I) according to a recipe for the rubber mixture; providing a transport system that feeds the cutting subassemblies (118, 118', 118") and that transfers the bales (A I, B I, C I) and the pieces (A IJ, B IJ. C IJ) of rubber toward at least one mixer; weighing the bales (A I, B I, C I) to obtain the weight of the bales (A I, B I, Ci); comparing the weight of the bales (A I, B I, C I) with the required weight of the batch; and transporting the bales (A I, B I, C I) and the pieces (A IJ, B IJ. C IJ) between the supply station, via feed belt (14, 114) to the cutting station and the mixer according to a sequence determined by the equivalence between the required weight of the batch and (a) the weight of the bales (A I, B I, C I) or (b) a sum of the weight of the bales (A I, B I, C I) and a weight of the pieces (A IJ, B IJ. C IJ).