Capacity requirements evaluation in JAP

20. 6. 2020

Capacity requirements evaluation in JAP.

View capacity requirements at workplaces and their constraints.

After each customer order has its own networks created with all internal orders and various sub-assembly parts and row parts (see previous post), we can perform the next step. We assign capacitive demands to produce all customer orders with all internal orders. There are at least two main kinds of capacities or capacity categories. The first one is work-center capacity and the second one is pooled capacity (labor/group of employees).

There are transactions to manage these capacities (CR01/CR02/CR03 for work-center capacity and CR11/CR12/CR13 for pooled capacity). For detailed information, see the SAP Help-Portal.

Example CR02:

In this part of JAP, these available capacities will be confronted /compared to capacity demands. The process shows us where a remedy is needed and which kind of remedy to use.

How do we create capacity demands?

There are many various methods available. Many APS systems and Add-Ons for SAP use plenty of them. They are sophisticated at various levels. In my opinion, this is not necessary (and this is one of the reasons I developed JAP).

JAP and capacitive scheduling:

The aim is to acquire a rough overview of the capacitive situation in a plant. It is not necessary to check on whether or not all the needed connections between work operations, machines, etc. are in place.We acquire the necessary information in regard to where the constraints and the bottlenecks exist. Through this constraint piece, the whole production process is managed using commonsense principles (additional details are coming soon in another post). 

Example of a capacitive situation in a plant (the red color indicates a critical resource):

                          

So here are the principles of the ABAP program, step-by-step:

Once we have created a collective order (order networks), we use an ABAP routine (class method) to go through that network and all its internal orders and plan orders.For each SAP order (regardless of whether it is an internal order or plan order), an ABAP class method selects from the database table KBED (Capacity Requirement Table KBED made in MRP-Task) all required work operations for this order and all details needed, such as operation duration, work place, etc.Then, all operations of the order are scheduled according to the order due dates and settings for scheduling in SAP (e.g., scheduling margin key, scheduling type, etc.).

For this purpose, the SAP function modules are used. 

 DATE_CONVERT_TO_FACTORYDATE
CR_SCHED_VIA_OPERATING_TIME
POINT_IN_TIME_CONVERT
DATE_TIME_CONVERT

The process is as follows (class method) 

 METHOD dispatch_due_to_soll. 
create_ags_table( ). " terminate_ags_table( ). 
ags_in_zzkbed_write( ). 
ENDMETHOD.

All work operations with their new due dates are stored in a custom table in the database titled ZKBED.

Then, all work operations are scheduled once again, in this case, depending on available capacity at the workplace. This is done in a LOOP circle over the custom database table ZKBED. Step by step, each workplace is added and all work operations assigned to that particular workplace are scheduled according to the available capacity at that workplace.

See the ABAP class method DISPATCH_MAIN:

METHOD dispatch_due_to_soll.
METHOD dispatch_main. 
CLEAR: lv_arbpl. 
LOOP AT lt_arbpl INTO lv_arbpl. get_table_dispatch( ). 
remove_from_zzkbed( ). 
level_ruin( ). 
move_block_to_future( ).
level_due_to_exchange( ). 
set_tab_atribute( ).
dispatch_into_zzkbed( ). 
CLEAR: lv_arbpl. 
ENDLOOP. 
ENDMETHOD.

This is the key action. After that, there are work operations scheduled at all the workplaces, and we can evaluate the bottleneck: 1. Take an action according to the theory of constraint. 2. Manage the plant through the drum-buffer-rope method. 3. All work places have their own scheduled working plans to be accomplished.

The following illustrations show examples of how can one evaluate available capacity and capacitive demands:

Green line available capacity, blue bars capacitive demands

Group of employees (personal resource)

There are many details, settings, and customizing options available, but the aim of this post is to give a general overview of JAP and to present the main principles of scheduling with JAP. From my perspective, a number of plant managers aim at scheduling precisely at each workplace using various APS Add-Ons, and that costs them too much in time and energy. They should be focused only on what is essential. In other words, on any bottlenecks. My JAP serves me sufficiently to reach that goal.

I am going to publish the whole ABAP coding for JAP on this web page in the future………