“…We assume that if a turret of type j is installed at the k-th position, then the execution time of operations from N dkjl is equal to t h (P dkj )=τ g b kj + P b kj l¼1 t b (P dkjl ), j = 1, 2, where τ g is an additional fixed time for one rotation of turret (Battaïa et al 2014). If the spindle head is installed, then t h (P dkj ) = t b (P dkj1 ), j = 1,2.…”