Method for determining and eliminating the drivers of non-value added cost due to product complexity and process parameters
View Patent ↗A method for measuring and reducing the cost of complexity in producing products or providing a service by comparing selected non-value added steps in the manufacturing or service process with the number of different products or services provided, so as to provide the non-value added cost of the product or service for various selected complexities. The number of products required to be processed or held in inventory for a particular demand, or the number of different specific services required for a particular demand of the service is determined by comparing the number of different product part numbers, or service categories offered, with selected non-value added steps in the respective processes. Mathematical analyses are derived from equations of motion of process improvement including the first derivative of process velocity.
1. A computer implemented method for reducing the work in process at a given time in the manufacture of one of a product and a series of products by comparing process activity parameters including process setup time and process time per product unit, with the number of different product part numbers processed, changing at least one of said process activity parameters to reduce said work in process, said method including the steps of:
determining, by a computer, the aggregate demand in product units per hour based on the number of different product units produced at a facility multiplied by the customer demand rate for respective product units per hour;
determining, by a computer, the common minimum batch size for all product units (MINB) for all workstations from the equation:
MINB
=
λ
[
∑
i
=
1
N
S
1
-
∑
i
=
1
N
λ
P
]
=
Δ
S
1
-
Λ
P
where λ is the customer demand rate, N is the number of different product part numbers (from i to N), Λ is the aggregate demand for all product units produced in the facility, S is the setup time required to prepare a workstation to produce a batch of product units and P is the time required to process one product unit at the workstation in question; and
reducing said work in process by selective reduction of at least one of said product part numbers, said process setup time and said process time per product unit.
2. The method set forth in claim 1 including the step of:
comparing the non value added cost of process time per product unit with the number of product part numbers being processed.
3. The method set forth in claim 2 including the step of:
determining the common workstation turnover time (WTT) for all workstations processing N product part numbers from the equation:
WTT
=
NS
1
-
Λ
P
wherein all product units have the same demand, setup time and process time per product unit.
4. The method set forth in claim 3 including the step of:
comparing the non value added cost of defective product units with the number of product part numbers being produced.
5. The method set forth in claim 3 including the step of:
comparing the non value added cost of demand in product units per unit of time with the number of product part numbers being processed.
6. The method set forth in claim 3 , including the step of:
determining the average total system inventory in a facility for perfectly synchronized average Work In Process from the equation:
[
(
Λ
P
)
J
Λ
S
1
-
Λ
P
]
+
[
N
Λ
S
2
(
1
-
Λ
P
)
]
wherein all product units have the same demand, setup time and process time per product unit.
7. The method set forth in claim 3 including the step of:
determining the average total system inventory in a facility for setup-on-batch-arrival average Work In Process from the equation:
[
J
Λ
S
1
-
Λ
P
]
+
[
N
Λ
S
2
(
1
-
Λ
P
)
]
wherein all product units have the same demand, setup time and process time per product unit.
8. The method set forth in claim 3 including the step of:
determining the average total system inventory in a facility for fully asynchronized average Work In Process from the equation:
[
N
J
Λ
S
1
-
Λ
P
]
+
[
N
Λ
S
2
(
1
-
Λ
P
)
]
wherein all product units have the same demand, setup time and process time per product unit.
9. A computer implemented method for reducing the work in process at a given time in the manufacture of one of a product and a series of products by comparing process activity parameters including process setup time, processing time per product unit and the number of different product part numbers processed, at one or more workstations, including the steps of:
determining, by a computer, maximum workstation turnover time to produce one minimum size batch of each product at each workstation (WTT max ) from the equation:
WWT
max
=
Max
j
=
1
,
J
[
∑
i
=
1
N
S
ij
1
-
∑
i
=
1
N
λ
i
P
ij
]
wherein, i=part product index (i=1, . . . , N) and N is the total number of different parts or products, j equals the workstation (j=1, . . . , J), J is the number of distinct workstations, λ i is the customer demand rate for part product i in units per hour, S ij is the setup time required to prepare workstation j to produce a batch of part/product i and P ij is the time required to process one unit of part/product i at workstation j; and
changing selected ones of said process activity parameters to reduce said workstation turnover time.
10. A computer implemented method for reducing the work in process at a given time in the manufacture of one of a product and a series of products by comparing process activity parameters including process setup time, processing time per product unit and the number of different product part numbers processed, at one or more workstations, including the steps of:
determining, by a computer, the batch size (MINB i ) for N products from the equation:
MINB
i
=
λ
i
WWT
max
=
λ
i
Max
j
=
1
,
J
[
∑
i
=
1
N
S
ij
1
-
∑
i
=
1
N
λ
i
P
ij
]
wherein, i=part product index (i=1, . . . , N) and N is the total number of different parts or products, j equals the workstation (j=1, . . . , J), J is the number of distinct workstations, λ i is the customer demand rate for part product i in units per hour, S ij is the setup time required to prepare workstation j to produce a batch of part/product i and P ij is the time required to process one unit of part/product i at workstation j; and
changing selected ones of said process activity parameters to reduce said work in process.