16 Production Planning of Remanufactured Products with Inventory …
221
and a new NRU, and remanufactured products with a recovered RU and a new NRU.
Hence, the demand quantity generated every time interval is always satisfied. The
collected product inventory stores the collected products to procure RUs by disassembling. The collected Rus are employed for remanufacturing, and the collected
NRUs are disposed of. Also, when the recovery of RU is more than product demand,
they are used for other products. The management costs of the two inventories are
simulation parameters.
16.2.2 Assumptions Regarding LCS and Production Methods
The following assumptions for constructing LCS software have been made.
(1) The cost for remanufacturing that includes the cost for collection and disassembly of used products is smaller than that for newly manufacturing. Therefore,
remanufactured products are preferentially produced than newly manufactured
products. New manufacture is compensated only for the insufficient amount or
products that cannot be met by only remanufactured products to satisfy demand.
(2) New manufacture is carried out by lot production. On the other hand, remanufacturing is carried out by either continuous production or lot production. If the
finished product inventory is less than the demand at time t, new manufacture
is ordered to satisfy demand.
(3) When the number of collected used products is higher than demand, all the
products shipped to the market are remanufactured products. Collected RUs
that are not shipped to the market are reused or recycled for other products for
convenient.
(4) Required time for newly manufacturing, remanufacturing, collection of used
products, and disassembly are less than the time interval in LCS.
As for item (2), the lot size for new manufacture is determined by
Q M (t; i M ) =
t+i M
∫
t
(λ(t) − γ (t))dt,
(16.1)
where i M is ordering interval decided in advance, λ(t) and γ (t) are the demand quantity at time t and the collecting quantity of used products at time t, respectively. It is
noted that when Q M (t) has a large value, the number of ordering of new manufacture can be reduced; however, excessive inventory of newly manufactured products
is likely to occur.
As for continuous production in remanufacturing, remanufactured products arise
in every time interval of LCS, which yields the production quantity of remanufactured
products at time t is the same as the collecting quantity γ (t). As for lot production
in remanufacturing, an order is placed at the time interval i R . Therefore, the lot size
for remanufacturing is determined by
221
and a new NRU, and remanufactured products with a recovered RU and a new NRU.
Hence, the demand quantity generated every time interval is always satisfied. The
collected product inventory stores the collected products to procure RUs by disassembling. The collected Rus are employed for remanufacturing, and the collected
NRUs are disposed of. Also, when the recovery of RU is more than product demand,
they are used for other products. The management costs of the two inventories are
simulation parameters.
16.2.2 Assumptions Regarding LCS and Production Methods
The following assumptions for constructing LCS software have been made.
(1) The cost for remanufacturing that includes the cost for collection and disassembly of used products is smaller than that for newly manufacturing. Therefore,
remanufactured products are preferentially produced than newly manufactured
products. New manufacture is compensated only for the insufficient amount or
products that cannot be met by only remanufactured products to satisfy demand.
(2) New manufacture is carried out by lot production. On the other hand, remanufacturing is carried out by either continuous production or lot production. If the
finished product inventory is less than the demand at time t, new manufacture
is ordered to satisfy demand.
(3) When the number of collected used products is higher than demand, all the
products shipped to the market are remanufactured products. Collected RUs
that are not shipped to the market are reused or recycled for other products for
convenient.
(4) Required time for newly manufacturing, remanufacturing, collection of used
products, and disassembly are less than the time interval in LCS.
As for item (2), the lot size for new manufacture is determined by
Q M (t; i M ) =
t+i M
∫
t
(λ(t) − γ (t))dt,
(16.1)
where i M is ordering interval decided in advance, λ(t) and γ (t) are the demand quantity at time t and the collecting quantity of used products at time t, respectively. It is
noted that when Q M (t) has a large value, the number of ordering of new manufacture can be reduced; however, excessive inventory of newly manufactured products
is likely to occur.
As for continuous production in remanufacturing, remanufactured products arise
in every time interval of LCS, which yields the production quantity of remanufactured
products at time t is the same as the collecting quantity γ (t). As for lot production
in remanufacturing, an order is placed at the time interval i R . Therefore, the lot size
for remanufacturing is determined by