Souderton, PA. August 9, 2013 – Recently, an Abar/Ipsen vertical bottom-loading vacuum furnace, located in NE Ohio, suffered major damage due to a quench fan failure. One of the fan blades dislodged during a cooling operation and pierced the water-cooled heat exchanger that surrounds the fan wheel assembly. This resulted in the entire vacuum chamber filling with water. The 72” D x 72” H hot zone was removed and sent to Solar Manufacturing for redesign and rebuilding.
The top hot zone sliding “bung,” which caused some of the problem, was replaced with an internal fixed baffle made of graphite board and felt insulation. The low carbon steel fan wheel, which had caused the damage, was replaced with a 304 SS fan wheel that was vacuum stress relieved and balanced with a 75 HP motor armature. The entire original internals, consisting of combinations of graphite tube heaters, ceramics, molybdenum hot face, and Kaowool insulation were replaced with nine (9) low-mass, segmented, circular, graphite element bands and an insulation pack consisting of multiple layers of graphite felt with a graphite foil hot face. In addition, a variable frequency drive (VFD) was incorporated on the quenching fan motor to allow for constant -5” Hg argon quenching pressure, providing a much-improved cooling rate.
The rebuilt hot zone was returned to the customer’s plant and reinstalled into the furnace chamber. Solar Manufacturing service engineers were on-site after installation to start-up the furnace and demonstrate that the new hot zone met all applicable tests including vacuum, AMS 2750E temperature uniformity survey, and GE heating and cooling rates for stator components. This entire project, from order placement to final acceptance, was completed within three months.