Intermet Earns Patent For Machinable Austempered Ductile Iron

Aug. 8, 2006
… already in use for control arms and steering knuckles

August 8, 2006 -- Intermet Corp.'s Domestic Ferrous Group has earned a U.S. patent for its Machinable Austempered Ductile Iron (MADI), a material that is already in application for control arms and steering knuckles that Intermet produces in Lynchburg, VA.

Troy, MI-based Intermet is a producer of cast-metal components for automotive, commercial vehicle, and other industrial markets. MADI is said to offer better strength characteristics to traditional ductile iron, and better machinability and reliability (“fatigue performance”) (reliability) than traditional austempered ductile iron.

The patent, granted in July, covers the MADI material as well as the manufacturing process – including a proprietary heat-treating technique.

MADI was developed by Intermet researchers in 2001 as a material for automotive structural and powertrain components. Intermet now uses it to manufacture safety-critical parts, at lower cost and better performance characteristics than competing designs like steel forgings, welded steel assemblies, or aluminum castings.

In addition to the steering knuckles and control arms, Intermet has developed MADI engine crankshafts for a professional drag racer (National Hot Rod Assn.)

Dr. Alan Druschitz, co-developer of MADI and technical manager at Intermet's Archer Creek Foundry in Lynchburg, states: "Today's vehicle and industrial equipment manufacturers demand components that are both durable and lightweight. Because the design strength of MADI is 50 to 100% higher than current as-cast ductile irons, significantly lighter weight components can now be designed. MADI will lead to the increased use of low-cost ductile-iron castings since for the first time improved mechanical properties and improved machinability both have been achieved."