Example 5
This diagram shows an example of operations overlap. The queue and setup are done sequentially. Assume that operations have overlap expressed as a percent (100% = total overlap, 0% = no overlap) or send ahead quantity. If overlap is expressed as a percentage, assume that all units are available for processing at the start of the run or soon after:
| Operation | Operation Start | Run Start | Operation Due |
|---|---|---|---|
|
10 |
Day 1, 8:00 a.m. |
Day 1, 9:00 a.m. |
Day 1, 2:00 p.m. |
|
20 |
Day 1, 1:00 p.m. |
Day 1, 4:00 p.m. |
Day 2, 2:00 a.m. |
Forward Scheduling Calculations
Production ID Start Date and Time = Day 1, 8:00 a.m.
This table lists the steps that you take to calculate the start and due date and times for the first operation (Operation 10):
| Step | To Calculate | Use | Notes |
|---|---|---|---|
|
1 |
Operation 10 start date and time |
Production ID's start date and time |
This calculation assumes that queue doesn't occur in the first operation. |
|
2 |
Operation 10 run start date and time |
Operation start date and time + setup time |
None. |
|
3a, or |
Operation 10 run time (time/unit) |
Operation start quantity x run rate (converted to hours) + fixed run (converted to hours) |
Use this calculation if the run rate is in terms of time per unit. |
|
3b |
Operation 10 run time (units and time) |
Operation start quantity / run rate (converted to hours) + fixed run (converted to hours) |
Use this calculation if the run rate is in terms of units per time unit. |
|
4 |
Operation 10 due date and time |
Run start date and time + run time |
None. |
This table lists the steps that you take to calculate start and due dates and times for the second operation (Operation 20):
| Step | To Calculate | Use | Notes |
|---|---|---|---|
|
1a, or |
Operation 20 start date and time; overlap expressed as a percentage |
Prior operation's (Operation 10) start of run + [prior operation's total run time x (1 - overlap percent / 100)] + prior operation's intransit time + current operation's queue time |
None. |
|
1b |
Operation 20 start date and time; overlap expressed as a send ahead quantity |
Prior operation's (Operation 10) start of run + (prior operation's run rate x send ahead quantity, converted to hours) + prior operation's fixed run time + prior operation's intransit time + current operation's queue time |
None. |
|
2 |
Operation 20 run start date and time |
Current operation start date and time + setup time |
None. |
|
3a, or |
Operation 20 run time (time/unit) |
Operation start quantity x run rate (converted to hours) + fixed run (converted to hours) |
Use this calculation if the run rate is in terms of time per unit. |
|
3b |
Operation 20 run time (units/time) |
Operation start quantity / run rate (converted to hours) + fixed run (converted to hours) |
Use this calculation if the run rate is in terms of units per time unit. |
|
4 |
Operation 20 due date and time |
Current operation run start date and time + run time |
If you have a schedule with more than two operations, repeat steps 1 through 4 in this table until all subsequent operation due dates and times are calculated. |
Backward Scheduling Calculations
Production ID Due Date and Time = Day 2, 2:00 a.m.
This table lists the steps that you take to calculate the start and due date and times for the last operation (Operation 20):
| Step | To Calculate | Use | Notes |
|---|---|---|---|
|
1 |
Operation 20's due date and time |
Production ID's due date and time - current operation's intransit time |
None. |
|
2a, or |
Operation 20 run time (time/unit) |
Operation start quantity x run rate (converted to hours) + fixed run (converted to hours) |
Use this calculation if the run rate is in terms of time per unit. |
|
2b |
Operation 20 run time (units/time) |
Operation start quantity/ run rate (converted to hours) + fixed run (converted to hours) |
Use this calculation if the run rate is in terms of units per time unit. |
|
3 |
Operation 20 run start date and time |
Current operation's due date and time - run time |
None. |
|
4 |
Operation 20 start date and time |
Current operation's run start date and time - setup time |
None. |
This table lists the steps that you take to calculate start and due dates and times for the prior operation (Operation 10), with an operation overlap expressed as a percentage:
| Step | To Calculate | Use | Notes |
|---|---|---|---|
|
1 |
Operation 10 due date and time, when operation overlap is expressed as a percentage |
Subsequent operation's (Operation 20) start date and time - subsequent operation's queue time - current operation's intransit time + [current operation's total run time x (overlap percent / 100)] |
None. |
|
2a, or |
Operation 10 run time (time/unit) |
Operation start quantity x run rate (converted to hours) + fixed run (converted to hours) |
Use this calculation if the run rate is in terms of time per unit. |
|
2b |
Operation 10 run time (units/time) |
Operation start quantity / run rate (converted to hours) + fixed run (converted to hours) |
Use this calculation if the run rate is in terms of units per time unit. |
|
3 |
Operation 10 run start date and time |
Current operation's due date and time - run time |
None. |
|
4 |
Operation 10 start date and time |
Current operation's run start date and time - setup time |
If you have a schedule with more than two operations, repeat steps 1 through 4 in this table until all prior operation due dates and times are calculated. |
This table lists the steps that you take to calculate start and due dates and times for the prior operation (Operation 10), with an operation overlap expressed as a send ahead quantity:
| Step | To Calculate | Use | Notes |
|---|---|---|---|
|
1 |
Operation 10 due date and time, when operation overlap is expressed as a send ahead quantity |
Subsequent operation's (Operation 20) start date and time - current operation's intransit time - subsequent operation's queue time + [current operation's run time x (Operation start quantity - send ahead quantity)] |
None. |
|
2a, or |
Operation 10 run time (time and unit) |
Operation start quantity x run rate (converted to hours) + fixed run (converted to hours) |
Use this calculation if the run rate is in terms of time per unit. |
|
2b |
Operation 10 run time (units/time) |
Operation start quantity / run rate (converted to hours) + fixed run (converted to hours) |
Use this calculation if the run rate is in terms of units per time unit. |
|
3 |
Operation 10 run start date and time |
Current operation's due date and time - run time |
None. |
|
4 |
Operation 10 start date and time |
Current operation's run start date and time - setup time |
If you have a schedule with more than two operations, repeat steps 1 through 4 in this table until all prior operation due dates and times are calculated. |