Scot Forge Produces Record Size Rolled Ring For New Subs

The U.S. Navy, through subcontractor Martin Marietta, had been trying to procure a ring destined to be part of the new, advanced-design stealth propulsion system for the Seawolf class submarine. The propulsion system is super silent and reportedly undetectable by current sonar systems. The ring needed known as a propulsor cone — was to have both inner and outer diameter profiles, and would finish at just under 200-in. O.D. and 42- in. face.

In mid-1994, Scot Forge installed a new fully automatic Wagner Ring Mill, reportedly one of the largest and most advanced in the world.

With 450 tons of radial force (400 metric tons) and 280 tons of axial force (250 metric tons), the new ring mill, in conjunction with an inhouse, 3,000-ton hydraulic open die press, had the ability to do exactly what the Navy needed. Scot Forge won the order.

The company worked closely with the material supplier, Electralloy, a G.O. Carlson Co., which poured a 67-in. (170-cm) Nickel Aluminum Bronze (UNS C63200) ingot weighing 50,000 lbs. (23,000 kg). The alloy—while rarely used in forgings of this size — was chosen for its strength, resistance to corrosion and damping capacity (ability to absorb sound).

Rolling sequences were initially simulated using Rolltech, a software created specifically for the Scot Forge ring mill. After the ring mill was modified for the task, production took place and the result is the largest known defect-free profiled Nickel Aluminum Bronze ring in the world. Scot Forge, which received ISO 9002 certification in 1992, has been a leading manufacturer of open die forgings for more than 100 years.

For more information from Scot Forge Circle 151 on Reader Service Card