As an example of the cost savings attributed to using LED lamps, first choose the value that most closely represents your per-hour cost of having a machine down. Then figure in the approximate cost-per-hour of your maintenance labor rate and the cost-per-hour of the machine operator. The results are the approximate savings an LED lamp can offer in its ten-year life span.

If you want to do the math based on your own figures, here's the formula we used. (M = the cost of machine downtime per hour; L = the cost of maintenance labor per hour; O = the cost of operator labor, per hour; and T = the time it takes to change a bulb [we used 25 hours, by the way, but the actual time could be different].) 
(see Figure N)

(M+L+O) x T x 35 = Cost of conventional lamps for 10 years (see Figures O.1, O.2, O.3)

To get the total costs, of course, you'll have to add in the number of LED lamps that you are replacing and the energy savings that you will achieve over ten years (average life of the LED lamp).