Tailor-made calendering solutions for rubber and thermoplastics

For a leading company engaged in the research, formulation, manufacture and industrial supply of semi-finished rubber products for a wide range of sectors, Rodolfo Comerio has delivered a project comprising four machines, designed to increase productivity, safety and process quality, while complying with the latest CE regulations. The main requirement was to develop high-performance two-roll open mixing mills capable of increasing productivity; reducing machine downtime; ensuring the highest standards of operator safety.

The core of the innovation lies in the adoption of Bosch Rexroth Hägglunds hydraulic motors, selected for their performance and full compliance with the most stringent safety regulations. Their main advantages include: emergency stop in less than 10 degrees, well below the regulatory limits; maximum torque available even at extremely low speeds (0.1 rpm); estimated productivity increase of between 15% and 20%; elimination of gearboxes and cardan shafts, resulting in greater reliability, reduced energy losses, lower maintenance requirements, and immediate, dynamic torque control, even under rapid speed variations. This configuration provides process engineers with unprecedented operational flexibility, enabling them to optimise formulations and compound quality without mechanical constraints. The system also incorporates an automatic knife system for cutting the material as it exits the mixing mill, together with fully safety-oriented solutions that eliminate the risk of direct operator contact with moving parts.

The engineering and manufacture of the plant required approximately six months, a particularly short timeframe considering the complexity of the machines and the production of rolls weighing more than 12 tonnes each. In even more complex projects, however, the longest phase is typically the commercial and project definition stage, which may last for more than a year. Despite this, Rodolfo Comerio is able to deliver its plants in line with processors’ operational requirements and, in this particular case, completed delivery one month ahead of the contractual schedule, enabling the customer to carry out installation during the Christmas production shutdown, a crucial factor in the rubber industry.

The collaboration with Bosch Rexroth will continue over the coming years through the development of next-generation calenders and mixing mills for specialised applications. Some of these innovations will be showcased at the Comerio Calendering Technology Center, an internationally recognised facility where processors can test production solutions on reconfigurable pilot lines.

The key strength of the Varese-based manufacturer lies in its exceptional level of customisation: every plant is developed to meet specific customer requirements. In many cases, customers approach the company with a particular material or compound and ask whether it is possible to design a process for its production. Rodolfo Comerio’s answer is always a dedicated engineering solution. “No two machines are ever the same, because every line is tailor-made and always incorporates innovative features,” explained Francesco Fiamminghini, Executive Managing Director – Purchases, Finance and Logistics at Rodolfo Comerio.

The solution developed reflects one of Rodolfo Comerio’s core strengths: every plant is designed on the basis of advanced structural analysis, using finite element calculations to verify stresses, pressures and mechanical strength. Rodolfo Comerio calenders are distinguished by their heavy-duty, high-rigidity structures, the use of solid materials rather than box-section constructions, and outstanding mechanical precision, maintaining extremely tight tolerances even under load. These characteristics ensure long-term stability, operational reliability and an exceptionally long service life.