PAUL VICTOR HAAS
Pilots at Fairways Ln, Saint Paul, MN

6455815, Sep 24, 2002

Nov 8, 2001

10/008040

Hans L. Melgaard - North Oaks MN
Paul J. Haas - White Bear Lake MN

Despatch Industries, L.L.P. - Minneapolis MN

F27B 514

219390, 219393, 219400, 148108, 148121

An oven for magnetic annealing of magnetic media, along with methods for using the same. The oven has a vacuum chamber with vacuum port for loading and unloading magnetic media. The vacuum port is sealed by a vacuum seal or door adapted for movement between open and closed positions. A vacuum pump is connected to the chamber to provide a vacuum within the chamber. The oven includes a heat exchanger adapted to receive magnetic media and a heat transfer gas unit connected to the heat exchanger to form a closed, hermetically sealed heat transfer gas circuit for heating and cooling magnetic media loaded in the heat exchanger. A magnet located exterior to the vacuum chamber provides the magnetic field to magnetic media. Methods of the invention include the steps of loading magnetic media into the heat exchanger of the oven, closing the door to create a vacuum seal, generating a vacuum within the chamber, circulating heat transfer gas through the heat transfer gas circuit to ramp-up to the annealing temperature, providing a magnetic field of greater than 0. 25 Tesla, holding the temperature at the annealing temperature to allowing the magnetic material of the magnetic media to assume the desired orientation, ramping down the temperature to cool the magnetic media to preserve the desired orientation, ramping down and removing the magnet field, and reintroducing atmosphere into the chamber.