Production scheduling rules

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Production orders are scheduled automatically depending on the following:

A production order position in the queue.
Production orders with a higher position are scheduled first.
A production order start date.
The sequence of operations in the bill of materials (BOM).
Planning intervals of production departments.
Availability of the work centers or work center types.

For each production order, scheduling steps are the following:

Determine the sequence of operations as follows:
- If all operations consume components from stock, take the sequence from the BOM’s Operations tab.
- If an operation consumes a component that must be produced, include a sequence of operations from the component BOM. In the resulting sequence, these operations precede the operation that consumes the component.
Schedule operations from the sequence.

Scheduling operations from sequence

Operations are scheduled according to the following rules:

Find the work center types assigned to the operations.
Find the work centers included in the work center types.
Find Planning intervals of production departments that include work center types.
Check the work centers availability. If a work center type is not assigned to an operation, check the work schedule of a company specified in the production order.
Determine an operation start date as follows:
- If an operation is the first in the sequence, its start date is the production order start date.
- If an operation is NOT the first in the sequence, its start date is the date closest to the end date of the previous operation.
For each operation, determine how many times it is performed to produce the ordered product quantity. Do one of the following:
- If in the BOM, the Fixed checkbox is cleared for an operation, calculate the quantity of operations by the following formula:
  Quantity of operations = product Quantity in a production order / product Quantity in BOM
  
  If the resulting number is not integer, round it up.
- If in the BOM, the Fixed checkbox is selected for an operation, assume that operation is performed once.
For each operation, schedule the determined quantity of the operations on the planning intervals closest to the operation start date according to the work center availability or a company’s work schedule.
For each operation, determine the end time as follows:
a. Find the last planning interval that the operation is scheduled on.

b. Take the end time of this interval.

Production scheduling example

The production orders queue contains two production orders:

Number	Description	Priority	Start date	Due date
01	Production order for 2 stools	High	03.07.2020	06.07.2020
02	Production order for 8 stools	Medium	03.07.2020	06.07.2020

BOM for 1 stool includes the following:

Operations

Operation number	Next operation	Operation	Standard time	Fixed
1	0	Stool assembling	1 min	No

Components

Component	Quantity	Unit	Operation	Produce	Bill of materials
Stool leg	4	pcs	Stool assembling	Yes	Stool leg BOM for 5 legs
Stool seat	1	pcs	Stool assembling	No

A work center type is not assigned to the Stool assembling operation. This means that a company can perform this operation any number of times on any date within the company’s work schedule. The schedule is 5 work days a week starting from Monday. A work day is from 8 AM to 5 PM.

Stool leg BOM for 5 legs includes the following:

Operations

Operation number	Next operation	Operation	Standard time	Fixed
1	0	Wood sharpening	10 min	No

Components

Component	Quantity	Unit	Operation	Produce	Bill of materials
Beam	2	m	Wood sharpening	No

Details of the work center type assigned to the Wood sharpening operation:

Operation	Standard time	Work center type	Work center	Department	Planning interval
Stool assembling	10 min	Wood sharpening equipment	Wood sharpening machine	Production	5 min

These details show that the Wood sharpening machine is assigned to the Wood sharpening operation. This operation is performed in the Production department with the planning interval of 5 minutes. The Wood sharpening machine is available according to its availability schedule.

Scheduling flow

The scheduling flow includes the following:

Production order 01
Production order 02

Production order 01

The Production order 01 for 2 stools is on the top of the queue. So, it is scheduled first.

The scheduling steps are the following:

According to BOM, the following is required to produce 1 stool:
- Complete 1 Stool assembling operation.
- Produce 4 stool legs before performing the Stool assembling operation.
- To produce 4 stool legs, complete the Wood sharpening operation.
  So, the sequence of operations for production order 01 starts with Wood sharpening. The next and the last operation is Stool assembling.
Schedule the operations for production order 01.

Scheduling operations for production order 01

Operations for production order 01 are scheduled as follows:

Determine the following:
- The Wood sharpening equipment is assigned to the Wood sharpening operation.
- No work center type is assigned to the Stool assembling operation.
Determine that the Wood sharpening equipment includes the Wood sharpening machine.
Determine the following:
- Planning interval for the Wood sharpening operation is 5 min.
- Planning interval for the Stool assembling operation is not defined.
Determine the following:
- The Wood sharpening machine is available 9 hours a day from 8 AM to 5 PM.
  Any work day is available for scheduling operations.
- The company’s work schedule is 9 hours a day from 8 AM to 5 PM.
  Any work day is available for scheduling operations.
Determine that the production order start date is 03.07.2020.
Calculate how many times the operations must be performed:
- For the Wood sharpening operation, consider that 2 stools are ordered. For 2 stools, 8 legs are required. The stool leg BOM says that 1 Wood sharpening operation produces 5 legs. Then this operation must be performed 2 times.
- For the Stool assembling operation, consider that 2 stools are ordered. The stool BOM says that 1 Stool assembling operation produces 1 stool. Then this operation must be performed 2 times.

Put the Wood sharpening operation on the production schedule. Apply the following:

The Wood sharpening machine is available on any work day.Then the operation start date is the production order start date 03.07.2020. The operation start time is the machine start time 8 AM.
The operation Standard time is 10 min. In this example, it takes 2 Planning intervals of 5 min.

The operation must be performed 2 times. Then it takes 4 Planning intervals.

Date

03.07.2020

Planning intervals

8:00:00

8:04:59

8:05:00

8:09:59

8:10:00

8:14:59

8:15:00

8:19:59

8:20:00

8:24:59

12
planning intervals

9:25:00

9:29:59

9:30:00

9:34:59

Wood sharpening machine

PO1WS

where:
PO1WS - Production order 01, Wood sharpening operation

Put the Stool assembling operation on the production schedule. Apply the following:

Any work day is available on the company’s work schedule. Then the operation start date is the production order start date 03.07.2020.
The previous operation ends at 8:19:59 AM. Then this operation start time is 8:20.

A work center type is not assigned to the Stool assembling operation. Then assume that the company has unlimited capacity for performing this operation within Standard time. Then it takes 1 min to perform 2 operations.

Date	03.07.2020
Planning intervals	8:00:00 8:04:59	8:05:00 8:09:59	8:10:00 8:14:59	8:15:00 8:19:59	8:20:00 8:24:59	12 planning intervals	9:25:00 9:29:59	9:30:00 9:34:59
Wood sharpening machine	PO1WS	PO1WS	PO1WS	PO1WS
Company					PO1SA

where:

PO1WS - Production order 01, Wood sharpening operation
PO1SA - Production order 01, Stool assembly operation

Production order 02

The Production order 01 for 2 stools is scheduled. Then schedule the Production order 02 for 8 stools.

The scheduling steps are the following:

Determine the sequence of operations in the same way as for Production order 01 .
Schedule operations for Production order 02.

Scheduling operations for production order 02

Operations for production order 02 are scheduled as follows:

Determine the following:
- The Wood sharpening machine is occupied with production order 01 on 03.07.2020 up to 8:19:59. Then the machine is available from 8:20 AM to 5 PM.
- On the company’s work schedule, 03.07.2020 is available for scheduling operations from 8 AM to 5 PM.
Determine that the production order start date is 03.07.2020.
Calculate how many times an operation must be performed:
- For the Wood sharpening operation , consider that 8 stools are ordered. For 8 stools, 32 legs are required. The stool leg BOM says that 1 Wood sharpening operation produces 5 legs. Then this operation must be performed 7 times.
- For the Stool assembling operation, consider that 8 stools are ordered. The stool BOM says that 1 Stool assembling operation produces 1 stool. Then this operation must be performed 8 times.

Put the Wood sharpening operation on the production schedule. Apply the following:

The operation start time is 8:20 AM.
The operation Standard time is 10 min. In this example, it takes 2 Planning intervals of 5 min.

The operation must be performed 7 times. Then it takes 14 Planning intervals.

Date	03.07.2020
Planning intervals	8:00:00 8:04:59	8:05:00 8:09:59	8:10:00 8:14:59	8:15:00 8:19:59	8:20:00 8:24:59	12 planning intervals	9:25:00 9:29:59	9:30:00 9:34:59
Wood sharpening machine	PO1WS	PO1WS	PO1WS	PO1WS	PO2WS	PO2WS	PO2WS
Company					PO1SA

where:

PO1WS - Production order 01, Wood sharpening operation
PO1SA - Production order 01, Stool assembly operation
PO2WS - Production order 02, Wood sharpening operation

Put the Stool assembling operation on the production schedule. Apply the following:

The operation start date is 03.07.2020.
The operation start time is 9:30. For production order 02, it is the end time of the Wood sharpening operations.

Date	03.07.2020
Planning intervals	8:00:00 8:04:59	8:05:00 8:09:59	8:10:00 8:14:59	8:15:00 8:19:59	8:20:00 8:24:59	12 planning intervals	9:25:00 9:29:59	9:30:00 9:34:59
Wood sharpening machine	PO1WS	PO1WS	PO1WS	PO1WS	PO2WS	PO2WS	PO2WS
Company					PO1SA			PO2SA

where:
PO1WS - Production order 01, Wood sharpening operation
PO1SA - Production order 01, Stool assembly operation
PO2WS - Production order 02, Wood sharpening operation
PO2SA - Production order 02, Stool assembly operation
Both production orders in the queue are scheduled.

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