16 Production Planning of Remanufactured Products with Inventory …
227
influence of the differences between the predicted collecting quantity and the actual
one on the total cost, in which Fig. 16.7 is the case varying K M , and Fig. 16.8 is the
case varying h F . The ratio of an ordering cost for newly manufactured products to
an inventory holding cost for the finished products, K M / h F ranging [1250, 20000],
is also shown in Figs. 16.5, 16.6, 16.7, 16.8. The horizontal axis in Figs. 16.5, 16.6,
16.7, 16.8 represents how much the actual quantity is increased or decreased from
the predicted quantity, and also the vertical axis of them represents how much the
total cost is increased or decreased compared to the case where the predicted quantity
is the same as the actual quantity.
Comparing Fig. 16.5 with 16.6 and 16.7 with 16.8, we can see that the shape of
the curves in the figures is the same when the ratio K M / h F is the same. Therefore,
the influence of the prediction accuracy can be judged based on K M / h F . In all the
life-cycle stages, the larger the K M / h F , the higher is the impact on the total cost by
the different predictions. Also, the effect on the increase/decrease rate of the total
cost increases as time goes from the growth stage to the decline stage. Therefore,
when K M / h F has a significant value, or as the life-cycle stage is approaching the
decline stage, it is crucial to improve the predicting accuracy of the collection of the
used products and the product demand.
16.5 Optimal Production System for Remanufactured
Products: Lot Production or Continuous Production
16.5.1 LCS Conditions
We investigate the optimal remanufacturing system in this section: lot production
or continuous production. In the previous sections, remanufacturing was considered
focusing on the newly manufacturing cost under the conditions: an ordering cost
for remanufactured products K R = 0 and an inventory holding cost for the collected
products h C = 0. In this section, remanufacturing is evaluated under non-zero values
of K R and h C .
The ordering interval of new manufacture i M is fixed to each life-cycle stage such
that the growth stage, the maturity stage, and the decline stage are 9, 9, and 2 for
convenience, respectively, in which all the ordering intervals are the same as the
optimal number of ordering in the reference conditions in Table 16.1. The decline
stage, t ∈ [135, 250] in Fig. 16.1, is divided into decline stages 1 and 2. The former
is the stage during which the demand quantity is larger than the collecting quantity,
t ∈ [135, 160], the latter is the stage during which the collecting quantity is greater
than the demand quantity, t ∈ [160, 250]. The same set of parameters in the reference
conditions in Table 16.1 are applied. While parameters K R and h C are assigned as
shown in Table 16.3.
227
influence of the differences between the predicted collecting quantity and the actual
one on the total cost, in which Fig. 16.7 is the case varying K M , and Fig. 16.8 is the
case varying h F . The ratio of an ordering cost for newly manufactured products to
an inventory holding cost for the finished products, K M / h F ranging [1250, 20000],
is also shown in Figs. 16.5, 16.6, 16.7, 16.8. The horizontal axis in Figs. 16.5, 16.6,
16.7, 16.8 represents how much the actual quantity is increased or decreased from
the predicted quantity, and also the vertical axis of them represents how much the
total cost is increased or decreased compared to the case where the predicted quantity
is the same as the actual quantity.
Comparing Fig. 16.5 with 16.6 and 16.7 with 16.8, we can see that the shape of
the curves in the figures is the same when the ratio K M / h F is the same. Therefore,
the influence of the prediction accuracy can be judged based on K M / h F . In all the
life-cycle stages, the larger the K M / h F , the higher is the impact on the total cost by
the different predictions. Also, the effect on the increase/decrease rate of the total
cost increases as time goes from the growth stage to the decline stage. Therefore,
when K M / h F has a significant value, or as the life-cycle stage is approaching the
decline stage, it is crucial to improve the predicting accuracy of the collection of the
used products and the product demand.
16.5 Optimal Production System for Remanufactured
Products: Lot Production or Continuous Production
16.5.1 LCS Conditions
We investigate the optimal remanufacturing system in this section: lot production
or continuous production. In the previous sections, remanufacturing was considered
focusing on the newly manufacturing cost under the conditions: an ordering cost
for remanufactured products K R = 0 and an inventory holding cost for the collected
products h C = 0. In this section, remanufacturing is evaluated under non-zero values
of K R and h C .
The ordering interval of new manufacture i M is fixed to each life-cycle stage such
that the growth stage, the maturity stage, and the decline stage are 9, 9, and 2 for
convenience, respectively, in which all the ordering intervals are the same as the
optimal number of ordering in the reference conditions in Table 16.1. The decline
stage, t ∈ [135, 250] in Fig. 16.1, is divided into decline stages 1 and 2. The former
is the stage during which the demand quantity is larger than the collecting quantity,
t ∈ [135, 160], the latter is the stage during which the collecting quantity is greater
than the demand quantity, t ∈ [160, 250]. The same set of parameters in the reference
conditions in Table 16.1 are applied. While parameters K R and h C are assigned as
shown in Table 16.3.