Cromodora Wheels SPA installed a chip melting furnace for wheel production in Ghedi, Italy. The furnace, which has a capacity of 10,000 tons per year, was supplied and commissioned by Hertwich Engineering, a company of SMS group. Cromodora Wheels produces cast magnesium and aluminum wheels used for competition. Currently, the wheels are manufactured in a low-pressure casting process. The company is modernizing the recycling of its processing scrap with the new melting furnace.
In wheel production, machining chips regularly arise in large quantities in addition to a relatively low portion of piece scrap. Chip recycling is challenging because the unfavorable ratio of surface area and volume causes significant material loss through burn-off. The traditional method of recycling chips is to compact the chips before melting, which reduces the metal loss. However, it requires an additional work step with considerable consumption of energy.
Hertwich Engineering’s recycling system offers a more economical solution, provided there is a sufficiently large volume of chips. With the combination of the Ecomelt concept and a tailor-made plant technology, very low metal-loss values are achieved during operation. In addition to the melting furnace, the scope of supply included a chip pre-treatment facility with a bypass system for conveying the chips into separate transport containers.
The chips are centrifuged during pre-treatment. Chips of unfavorable shapes are processed in a chip crusher to ensure stable processing. Undesirable elements are removed by a separator during the process. The chips prepared in this manner are then fed into the melting furnace. In the first step the charged chips are heated in a dryer to approximately 752°F (400°C) within a few seconds using an intensive hot gas flow. The energy required is provided by hot gas from the melting furnace, and the flue gases from the dryer support the heating of the furnace. The preheated and cleaned chips are continually fed into the downward-directed melting flow and immediately drawn under the bath surface toward the furnace bottom. The fast melting almost completely avoids metal loss due to oxidation. The heat is removed to a very large extent from the flue gases in a regenerative combustion system and used to preheat the combustion air to approximately 1652°F (900°C).