A note on ‘A closed form solution for the G/M/r machine interference model’ by B. D. Bunday and E. Khorram

SUMMARY

In this note, we characterize the scope of the product form solution that has been presented in the paper, ‘A closed form solution for the G/M/r machine interference model’ (International Journal of Production Research, 1988,26, 1811-1818). In this paper, the machine interference problem has been solved for JV heterogeneous machines that are ‘repaired’ by a set of r operatives, which repair the machines in a service-in-random-order fashion. The authors solve the model allowing for different, independent and identically distributed times between breakdowns for each machine and different negative-exponential repair times for each machine. In this short critique, we show that the solution presented by Bunday and Khorram does not solve the classical machine interference problem unless the hypothesis of heterogeneous machines is relaxed.