Powder-metal parts earn top honors

In the Metal Powder Industries Federation's annual Powder Metallurgy Design Excellence competition, an end cover for a dipole cryomagnet used in the Large Hadron Collider (LHC) took top honors in the Other category for atypical PM components. The end cover for a dipole cryomagnet is used in the Large Hadron Collider, the largest and highest energy subatomic particle accelerator being built at CERN in Switzerland. annual Powder Metallurgy Design Excellence competition, an end cover for a dipole cryomagnet used in the Large Hadron Collider (LHC) took top honors in the Other category for atypical PM components. The winning parts in this competition represent advances in conventional press and sinter PM processing, metal injection molding (MIM), and hot-isostatic pressing (HIP). The superconducting dipole cryomagnets in the LHC operate at cryogenic temperatures (–456°F). The complex geometry of the end covers made HIP and PM an attractive near-net-shape technique for fabrication, says Stefano Sgobba, section leader in the Mechanical and Materials Engineering group of CERN, the European Organization for Nuclear Research, in Switzerland, which is building the LHC. "Closed or open-die forging would require significantly more machining. Welded covers would need extensive inspections and stress relieving. And casting would have poorer mechanical properties." The end covers are made from 316LN stainless-steel powder and HIPed to full density by in Sweden. Along with FEA and CAD, "Bodycote used CNC sheet-metal cutting and robotic welding and part manipulation to glean production rates 50 times greater than typically possible with fully dense HIPed near-net shapes," says Stephen Mashl, director of engineering and technology at Bodycote. The 253-lb near-net shape parts go to Finland for finishing. The machined 153-lb parts have complex features and tight mechanical tolerances. The outside of the curved surface has eight or 10 projections, and covers differ slightly depending on which side the dipole