A new ring-rolling mill is in operation for Ovako AB, fulfilling its initiative to increase capability for producing parts that are nearer to customers’ final dimensions. Ovako manufactures 500,000 metric tons/year of stainless steel for bearings, transportation, and engineering applications at its Horfors, Sweden plant, 220 km northwest of Stockholm. Its ring rolling capacity recently has been expanded by an estimated 75%, from about 30,000 to 55,000 metric tons/year, roughly equivalent to over 3.5 million custom-produced rings per year. The producer said its expansion is helping its customers to reduce process costs and reduce material waste.
Ovako’s rolled and forged steel rings are critical parts for manufacturers building roller bearing systems, automobiles, heavy trucks, and machine tools. And yet, the time and cost of machining can add to their handling costs and increase waste. The new capacity helps Ovako to produce parts nearer to dimensional specification, and that means its customers gain production time and cost efficiencies.
The entire production sequence for rings is under strict control at Horfors, starting with managing oxygen levels in the melting process to achieve exceptionally clean steels, and continuing through to precision ring rolling. Cleaner steels promote longer service for products with higher wear and corrosion resistance, and reduce maintenance and lifecycle costs.
Once formed, every ring is inspected for surface defects, variations in inside and outer diameters, width, height, conicity, ovality, and squareness, using a customized inspection system.
The near-net-shape rings have very tight tolerances for minimal deviation from each client’s desired net dimensions, according to Ovako, with small allowances to accommodate waste reduction targets. Some rings may heat treated before delivery, with thermal equipment available for normalizing, soft annealing, quenching and tempering, among other processes.
Ovako reports manufacture virtually any ring profile to meet individual customers’ requirements, in dimensions of 170-4,000 mm and weight ranges between 7-5,000 kg. Quality tests carried out on every batch, and deliveries are arranged to customers’ production programs.