Dynamic Lead Time

Dynamic lead time is production lead time that is dependent on order quantity as opposed to the information in fixed lead time.

Outcome

You understand how to use and calculate dynamic lead time both per manufacturing order and per operation, regarding within or beyond time fence, with or without shiftplanning, and forward and backward scheduling.

Dynamic lead time is used in both planning and executing manufacturing order.

Before you start

Whether lead time is fixed or dynamic is set for the product in field MO lead time method in 'Item. Connect Facility' (MMS003/F).

Lead time per manufacturing order

Lead time per manufacturing order (MO) is divided into the lead time to the first operation, the total lead time for each operation in the order, and lead time from the final operation to put-away.

Calculating lead time per order

Dynamic lead time is calculated by totaling the lead time components defined for the product. A time fence in days is set to reduce the number of lead time calculations. When the finish date for an order is within the time fence, lead time is calculated using order quantity and available capacity. Actual load is also used when the work center is defined for finite loading. If the item has no time fence, the orders is calculated as if it used fixed leadtime. A time fence is set for each facility in 'Item. Connect Facility' (MMS003).

Lead times for released orders are always calculated as if they were within the time fence, regardless of the finish date.

The day factor that indicates the percentage available capacity at the work center in order for the up- or downstream work center to start the same day. It is specified per work center.

Lead time per operation

The lead time for each operation is divided into queue time, external setup time, setup time, production time, and transit time. For fixed lead time, the lead time per operation is specified as the lead time offset for the operation start date. Transit and queue times do not affect lead time. Therefore, the description below is primarily for the components in dynamic lead time.

Calculating lead time per operation

Lead time is calculated for an operation by totaling the parts as stated in the formula below.

Que + Set/Res + Pce * Qty/(Ptq * Res) + Trp,

where

Que = Queue time (days) * Work center capacity per day

Set = Setup time recalculated in hours based on the time unit selected

Res = Planned quantity resources (labor or machine, depending on work center capacity type)

Pce = Run time recalculated in hours based on the time unit selected

Ptq = Price per time unit on the operation

Qty = Order quantity for the operation (including planned scrap)

Trp = Transport time (days, hours, percentage, or quantity) in hours based on the capacity per day of the work center

Compressing lead time

With orders using dynamic lead time, the lead time can only be compressed if the lead time components are changed, or overlapping is implemented. This can be done by changing the operation start dates in 'MO Operation. Reschedule' (PMS020).

Example - Dynamic lead time with shift planning and backward scheduling

Note: These examples only displays how the leadtime is calculated. It has nothing to do with how the W/C is loaded.

Assume the following to calculate dynamic lead time for shift planning and backward scheduling.

Op 020

 

Setup

Runtime

Queue

Day 5

10:30-11:00

11:00-18:00

20:00-22:00

Op 010

 

Setup

Runtime

Queue

Day 5

   

08:00-14:30

Day 4

 

08:00-12:00

13:00-16:30

Day 3

 

08:00-16:30

 

Day 2

13:36-14:51

13:36-14:51

 

Capacity

The capacity calendar for each work center indicates, in this example, when the product moved from the upstream operation can be received by the next (open time). Production is from Monday to Friday (five workdays per week). Each work center's capacity (operation capacity) is as follows.

Op.

Open

Cap/day

010

08:00-10:00

10:15-12:00

13:00-14:30

14:45-16:30

8 hrs

020

05:00-08:00

09:00-13:00

14:00-18:00

19:00-22:00

14 hrs

Order data

Order quantity is 60, planned scrap 15% in operation 010. The order finish date is day 5.

Operation data

The order includes two operations, 010 and 020. Operation 010 overlaps to operation 020. The number of resources indicates both setup and production resources. The table indicates the settings for each operation.

Op.

Queue (days)

Setup

Run

Price/ time code

Trnst time

No. rsrces

Qty

010

1.00

1 hrs

0.2 hrs

10

-2 hrs

1

67

020

0.25

1 hrs

0.2 hrs

1

1 hrs

2

60

Lead time per operation

Lead time is calculated back from the finish date at 23:00. Operation 010 is expected to be finished at 10:30. Therefore, production for operation 010 on day 5 can be between 10:15 and 10:30, and between 08:00 and 10:00. The remaining production is done from day 4 to day 2.

Op.

Fin day

Fin time

Lead time operation

Start day

Start time

020

5

22:00

0.25*8+(1/2+0.2*60/2)+1 = 9.50 hrs

5

10:30

010

5

10:30

1.00*8+(1+0.2*67)-2 = 20.33 hrs

2

13:36

Example - Dynamic lead time with backward scheduling, no shift planning

This example is for calculating dynamic lead time for backward scheduling and order without using shift planning. Assume the same basic data as in the previous example.

Op 020

 

Setup

Runtime

Queue

Day 5

10:30-11:00

11:00-18:00

20:00-22:00

Op 010

 

Setup

Runtime

Queue

Day 5

   

08:00-14:30

Day 4

 

08:00-12:00

13:00-16:30

Day 3

 

08:00-16:30

 

Day 2

13:36-14:51

13:36-14:51

 

Capacity

The capacity calendar per work center indicates when the product from the upstream operation can be received by the next (open time). The capacity calendar indicate the capacity per day when shift planning is not used. Production is from Monday to Friday (five workdays per week). Each work center's capacity (operation capacity) is as follows:

Op.

Cap/day

Op.

Cap/day

010

8 hrs

020

16 hrs

Order Data

The order quantity is 60, planned scrap is 15% for operation 010. The order finish date is day 5 at 23.00.

Operation Data

The order includes two operations, 010 and 020. Operation 010 overlaps to operation 020. The number of resources indicates both setup and production resources. The table indicates the settings for each operation.

Op.

Queue (days)

Setup

Run time

Price/ time code

Trnst time

No. rsrces

Qty

010

1.00

1 hr

0.2 hrs

10

-2 hrs

1

67

020

0.25

1 hr

0.2 hrs

1

1 hrs

2

60

Lead time per operation

Lead time is calculated back from the finish date at 24:00. Operation 020 uses (9.5/16) * 100 = 59.38% of available capacity on day 5. Therefore, production in operation 010 on day 5 can be 100 - 59.38% (= 40,62% of the days total capacity)), or 8 * 40.62 / 100 = 3.25 days. The remaining 17,08 hours is done ; day 4 (8h), day 3 (8h) and finaly 1,08 hour; day 2. In day 2 the production is experted to start when 1,08/8 * 100 = 13,5% remaining of the day.

For instance if the production runs from 8.00 to 16.00 it is expected to start at 14.55. Please note that when not using shift planning the start will only be stated in the date. The calculated time in this exemple is just to explain how M3 calculates.

Op.

Finish day

Cap avl. in %

Lead time operation

Start day

020

5

100

0.25*8+(1/2+0.2*60/2)+1 = 9.50 hrs

 

010

5

40.62

1.00*8+(1+0.2*67)-2 = 20.33 hrs

 
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