zone-levelhttp://www.oed.com/dictionary/zone-level_v%3Ftab%3Dmeaning_and_usezone level, v.
First published 1986; not fully revised

zone levelverb

  1. 1974–
    (transitive) .
    1. 1974
      The mixed alloy was then placed in a porcelain boat and zone-levelled by passing through 10–15 zones.
      Journal of Physics D vol. 7 33

Originally published as part of the entry for zone, n.

zone, n. was first published in 1921; not fully revised.