In Equation (7), CTOOL was set equal to 0.88 USD. CENERGY actually
varies in terms of process time, cumulative workload, and even
process seasons. However, in the case presented here, CENERGY was
held constant at a value of about 0.062 USD/kWh, the median electricity cost in South Korea. From the above, the manufacturing
cost can be calculated from both experimentally measured values
and numerically calculated values. Fig. 9 shows the resulting
manufacturing cost model. In some experimental points, calculated
values were slightly higher than the developed model, however the
overall trend between calculated cost and developed model is very
similar. Average error between nine measured points and the
developed model is about 8%. Since CTOOL was greater than CENERGY,
the tool cost was the dominant contributor to the total cost in the
case considered here. The overall manufacturing cost model
roughly followed the tool life surface. The manufacturing cost of
drilling 2000 holes was calculated to the nearest US dollar, and
could be reduced to about 60% of the current cost.