Features relating to maintenance of efficient operation

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Combinations or associations of metal-working machines not directed to a particular result according to classes B21, B23, or B24 (B23Q37/00, B23Q39/00 take precedence; features relating to operations performed, if the different metal-working operations are of the same kind, see the subclass for the kind of operation, e.g. punching B21D, welding B23K, grinding B24B; features relating to technically specified combinations of different metal-working operations B23P23/00) > Features relating to maintenance of efficient operation