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MAY 2018 • E&MJ; 51 www.e-mj.com OPERATING STRATEGIES • Compactness – One integrated piece of equipment. • Mobility – Modular construction for quick relocation. • Effi ciency – It can downsize a 63-in. tire in less than one hour. • Automation – Only one operator is required. • Green – Consumes up to 50% less energy than an excavator equipped with a shear. Salvadori said MT-REX is the fi rst ful- ly automated system capable of manag- ing tires up to 63-in.-rim diameter and providing a continuous fl ow of clean and consistently sized tire chunks. It can be operated by a single operator using a fork- lift; no overhead crane is necessary. With a processing time of less than one hour for a 63-in. tire, Salvadori claimed that MT-REX when continuously operated can downsize more than 7,000 tires per year and consistently feed more than 35,000 tons per year of clean and regularly cut pieces to a traditional shredding line. In operation, a forklift is used to place the tire in the cradle. In order to safely load the tire, proximity sensors help the forklift operator position it. The cradle can safely accommodate tires from 1.8-m outside diameter (OD) up to 4.1-m OD. Positioning is carried out in three movements: 1. The unit's mandrel probes the inside of the tire and pivots 90°. This places the tire on a horizontal plane. 2. The unit moves horizontally to auto- matically position tires with different diameters at different distances from the cutting unit. 3. Finally, the unit raises the tire to the preprogrammed height. These three movements place the tire in the most effi cient cutting location based on each tire's unique geometry. After each cut is performed the tire is automatically rotated a prescribed num- ber of degrees to prepare for the next cut. The positioning unit is fi tted with an appropriately sized mandrel designed to keep the tire in place during the cutting operation. Three mandrels are available to accommodate different rim dimensions. According to the company, if future tires exceeding 63-in. rim size are developed, MT-REX's confi guration can be expanded. The cutting unit performs tire downsiz- ing with a uniquely designed 1.5-m-long blade operated by high-pressure, dou- ble-effect oil hydraulic cylinders. The cutting depth and speed are customizable based upon tire geometry, tread dimen- sions and other parameters. This enables operators to select the optimum size of tire chunks while maximizing cutting speed. The cutting blades are designed to be quickly and easily replaced. A maximum shearing force in excess of 330 tons enables the continuous cut- ting operation. The blade geometry was engineered to transfer the shearing pow- er into the tire. The blade material and structure are designed to optimize cutting parameters, which include: – High cutting capacity; – High resistance to wear; – Repetitive impact strength; – Resistance to thermal shock; – Dimensional stability to heat treatment; – Ease of maintenance/replacement; and – Low operating cost. During the cutting process, the tire re- leases elastic energy as it is downsized. At the same time, signifi cant friction and pressure is exerted from the blades. MT- REX is robustly designed to handle these bursts of energy. The cut pieces are auto- matically removed by an electrically oper- ated conveyor belt that can be extended and connected to an external container or to the input feed of a traditional tire shredding line. The integrated conveyor keeps the rubber from being contami- nated by foreign objects such as rocks, which can damage shredders. For safety, fi xed guards surround the cutting area, with two side gates for maintenance access. These gates have an electric-safety lockout feature to pro- hibit entry during operation. Additionally, optical safety barriers protect the loading site. The system is compliant with Euro- pean Machinery Directive 2006/42/EC. Control Options MT-REX's operation can be preset via its PLC and touchscreen HMI manage- ment system. The PLC allows storage of multiple programs for the processing of different types of tires. In addition, MT- REX can also be operated from a radio frequency remote-control unit. An option- al internet-ready webcam connection is available to remotely diagnose the system and perform routine maintenance. The equipment is powered solely by electrical motors. Standard energy con- sumption is 40 kWh, which the company said translates to a few euros per hour of electric energy to operate. Diesel fuel is only required if an electrical generator is used. Even if electrical power is supplied by a diesel generator, fuel consumption is less than 50% of an excavator equipped with a shear, according to Salvadori. In comparison, the company said an excavator with a shear will burn more than 210,000 liters of fuel per year and require additional equipment to move inconsistently sized tire sections to the downstream process. This operation must be staffed by multiple people per shift, all whom are in close proximity to the down- sizing process involving multiton tires. Salvadori noted that despite its weight of nearly 42 tons and a footprint of 7 m by 14 m, the modularly constructed MT-REX makes teardown and installa- tion at another site just a two-day opera- tion — one day for disassembly and one day for reassembly. Sensors enable tires of different sizes to be positioned quickly for effi cient cutting. Cut pieces are loaded onto a built-in conveyor for transfer to a storage bin or shredding machine.