ThyssenKrupp Claims Near-Net-Shape Forging Process Enhances Performance

Developments in near-net-shape forging processes promise to enhance engine performance, strengthen components for oil and gas drilling and improve hermetic seals for high-power semiconductors.

ThyssenKrupp Metalúrgica Campo Limpo of São Paulo, Brazil says it has developed a new near-net-shape process for manufacturing integrated pistons for diesel engines that reduces processing time by up to 23 percent and significantly reduces tool wear.

“Our solution provides improvement on near-net-shape forging without the need of multi-axial tooling,” comments Segio Guerreiro of the company’s Advanced Engineering Group. “Usually a groove (in the form of a ring or collar neck) is forged using multi-axial tooling or is machined on the forging part. Working with the principles of reverse engineering, a new forging was developed without using expensive multi-axial tooling.” ThyssenKrupp Metalúrgica Campo Limpo would not disclose further details on the process, which it described as unique.

Tooling costs are dramatically reduced because the tool moves only axially. Dr. Guerreiro says the major gains for the customer are a 14 percent stock material reduction, a 14 percent weight reduction of the integrated pistons, a 23 percent reduction in machining time, a 20 percent reduction in tooling investment and a 50 percent improvement in die life with segmented tooling that was developed.Additionally, properties of the forging are said to be enhanced. “The forging is made without interruption of the forging due to the use of cutting tools,” says Guerreiro. “This enhances the mechanical properties of the piston.”

The technology development was driven by the move to more powerful truck diesel engines that must meet increasingly stringent environmental regulations. Optimization of pistons, connecting rods and crankshafts improves engine performance.

ThyssenKrupp Metalúrgica Campo Limpo was established as a Brazilian automotive supplier in 1954 and employs 3,100 today.

More commonly, near-net-shape forging is done through a process called orbital cold forging in which a moveable/orbiting top punch meets a fixed bottom die to work complex geometric pieces. The orbiting upper die rolls over a metal blank while the bottom die is raised hydraulically. The billet is kneaded into the bottom die.

Ronald J. Yurko, vice president of engineering for Latronics Corp., Latrobe, PA, says the orbital cod forging process can achieve dimensional tolerances of ±0.002-in on the outside diameter of a work piece. Latronics moved to near-net-shape forging as a way to improve mechanical properties and efficiencies of materials used to make metal-to-metal hermetic seals for semiconductor housings. The work hardening in the orbital cold forging process is particularly useful in making the components impervious to leaks.

Latronics now makes near-net-shape forgings for various applications, including gears, clutch parts, spots gear and oil and gas equipment.