Time constraint MAX


In the property Time constraint MAX, you specify the time for the relationship between this process and the previous process, as given by the Time constraint method.
Time constraint MAX is defined as "not longer than".

To set Time constraint MAX with an expression, please see this topic.

Format

The time specification should be given in one of the following formats: <Total move time>

:= <Move time>| <Move time> ';' ...
<Move time>
:= <Relative notation>| <Relative notation> '/' <Resource type>
| <Relative notation> '@' (Resource code)
| '#' <Production quantity>
<Relative time notion>
:= <Unit quantity> <Offset>...| <Offset>...
<Unit time>:= <Unit quantity> <Unit> | <Unit quantity>
<Offset>:= "+" <Unit quantity> <Unit quantity>
:= "+" <Unit quantity>
:= "-" <Unit quantity> <Unit quantity>
:= "-" <Unit quantity>
<Unit quantity>:= Integral value
<Unit>:= "S" | "M" |"H" | "D" | "W"
<Resource type>:= 'M' | 'S0' | ... | 'S9' | 'I0' | ... | 'I9'
| 'm' | 's0' | ... | 's9' | 'i0' | ... | 'i9'
<Production quantity>:= Real value

* <...> is a nonterminal symbol and (...) is a terminal symbol.
:= indicates that the notation of the table’s left cell is defined to be the term on the right of :=.
| means “or”.


Please see the Time constraint MIN help topic for setting examples.


If you specify <Relative Notation> with no other description after the <Relative Notation>, it means that the time is not measured along any particular resource's working time. Resource types in capital letters represent "assigned resource in the current process" and those in lower-case letters represent "assigned resource in the previous process".

However, if you specify the time beginning with "H" such as "H1D", it is meaningless to specify a resource.

For <Unit>, "S" stands for seconds, "M" stands for minutes, "H" stands for hours, "D" stands for days, and "W" stands for weeks. Specifying no unit means that the time is in minutes.
"1D" is equal to "24H" and "1W" is equal to "7D".

When "#N" (corresponding to N production quantity of the previous process) is specified for move time, the capacity value in the master data will not be referred to but the value will be calculated based on actually assigned time.


Notes about time constraint MAX

To use the time constraint MAX, you will check the property "Enable time constraint MAX" in the Settings tab of the project settings and specify values in the time constraint MAX field of the Integrated Master Editor.

Processes connected by the time constraint MAX will be assigned at once when scheduling. At that time, candidate resource combinations will be considered taking into account processes connected by the time constraint MAX. Therefore, the number of candidate resource combinations tends to be large when you use the time constraint MAX.

For example, suppose that the Integrated Master is set as follows. When the time constraint MAX is not used, there are three candidate resource combinations for process Pr1 and four for process Pr2, meaning that there are 7 candidate resource combinations in total.
When processes Pr1 and Pr2 are connected by the time constraint MAX (i.e., the time constraint MAX is specified for process Pr2), the two processes will be assigned at once when scheduling. In that case, there will be 3 x 4 = 12 candidate resource combinations.

[Integrated Master Editor]
ItemProcess numberProcess codeInstruction typeInstruction codeResource
A10Pr1Use instruction
A20Pr2Use instruction

Scheduling takes more time when there are more candidate resource combinations. In cases where scheduling takes too much by using the time constraint MAX, specifying a small number for the property "Max # resource candidate" will help reducing the scheduling time.
Click here for more information about candidate resource combinations.

Also, since operations connected by the time constraint MAX are assigned at once, dispatching orders of all the operations are the same. Therefore, the operations may be assigned in a different sequence from that of the dispatching rule of the scheduling parameter.


When the status of part of operations connected by the time constraint MAX is "Completed", "Started", "Frozen", or "Released", or times of those operations are partly fixed, you can use

  • Assign result constrained operations command
  • Assign time fix constrained operations command

to assign operations connected by the time constraint MAX and for which results are not specified.
For example, if you do not use the Assign result constrained operations command and Assign time fix constrained operations command as in the setting below, operations connected by the time constraint MAX and for which results are specified will be assigned in the first or second phase, and operations connected by the time constraint MAX and for which results are not specified will be assigned in the third phase at the same time when operations not connected by the time constraint MAX are assigned.

  1. Assign privileged operations
  2. Assign time fixed operations
  3. Assign/peg orders

In you insert the Assign result constrained operations command and Assign time fix constrained operations command as follows, operations connected by the time constraint MAX and for which results are not specified will be assigned in the third or fourth phase before operations not connected by the time constraint MAX are assigned. Thus, it is easy to satisfy the time constraint MAX constraint.

  1. Assign privileged operations
  2. Assign time fixed operations
  3. Assign result constrained operations
  4. Assign time fix constrained operations
  5. Assign/peg orders

What to do when unable to follow time constraint MAX

When "Assign/pegged orders" command or "Assign manufacturing orders" command is assigned, you may choose how to deal with cases in which operations cannot be assigned in line with the time constraint MAX by specifying the property "Assignment failed (time constraints MAX)" in the "Settings" tab of the scheduling parameter.

The following options are available for the property "Assignment failed (time constraints MAX)":

Assign outside scheduling period

The operations bound by the time constraint MAX are all forcibly assigned outside the scheduling period.

Ignore constraint

The operations originally intended for assignment will be individually assigned by ignoring the time constraint MAX.

Assign to dummy resource

The constrained operations are all assigned to dummy resources.


Restrictions

  1. Time constraint MAX is an optional feature and a separate license is required in order to use it.
  2. When there is a time constraint MAX constraint between orders, you need to make a setting so that the pegging between the orders will not be changed because scheduling will be performed with the pegging status immediately before scheduling. If you use the "Assign/peg orders" command to assign operations, the pegging status may be changed after assigning operations.
  3. Therefore, please use the "Assign manufacturing orders" command instead. Cases where dynamic splitting is specified for any one of operations for processes connected by Time constraint MAX are not supported yet.
  4. For master data in which processes are branched and merged, Time constraint MAX is not supported yet for between the branching point and merging point.
  5. If the pegging type is “Time constraint”, Time constraint MAX is not applied.

* Dynamic operation splitting means to split operations according to the split settings in resources and master use instructions. On the other hand, static operation splitting means to split operations according to the split settings in items and operations.


HelpNo.:754010
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