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How to Edit Precedence

Video Transcript:

Precedence is a significant constraint to consider when line balancing because it defines the required build sequence of your product or products. This means that when you're defining precedence, you want to think about which tasks have to follow other tasks and which tasks could be performed in parallel or don't require other taps be completed before they can be completed.

To get to the precedence network in Assembly Planner you want to make sure you have your routing open and then switch to the graph tab and you want to make sure that you have the routing and everything underneath it checked out. This is the warning that I'm seeing now because I don't have the check the routing checked out yet.

You want to make sure that no one has any of the operations or the activities underneath the routing checked out because in order to edit precedence you have to have the ability to edit all of the activities in the routing. So once you have a checked out if you're starting the precedence definition for the first time you want to decide where your starting point should be.

Do you want to assume that all tasks could be performed in parallel and you don't have very many build sequence restrictions, or do you want to start with the assumption that the sequence that you've defined your activities is for the most part the way the assembly has to be performed?

If you want to think about everything being in parallel then you can start with a blank predecessors column in the sheet view and what this means if we switch to the graph view is that all of these tiles represent activities and none of them are tied to one another. So this means at this point that any activity could be performed at any time now we know this isn't necessarily realistic but we're just looking for our starting point.

If you want to start with having to follow the sequence that's been defined routing and operations then you can click on the default precedence button and this is going to establish what we call a straight line precedence where each fought aged activity has to follow the one that precedes it as the activities are currently laid out. In the sheet view it will look like this so that the number called out in the predecessors row is indicating the task row which the current task has to follow.

So in this example, I have a one for this activity in row 2 which means that to be in row 1 has to precede the activity in row 2. Then the activity in row 2 has to precede the activity in Row 3 etc. If you switch to the graph view you see that all activities have been placed in line so that one activity always has to follow the next all the way down the task list.

So to make adjustments to the precedents will start in the sheet view if you want to remove a predecessor you can simply delete the value and this means that at this point the screw brackets together could be started at any time. If you have a task that is the predecessor for more than one other task then you would just have the value listed twice.

So by changing this now I'm saying that the tasks in row 4 and 5 can't be done until the task in Row 3 is done and if you have a task that can't be done until two other tasks have been completed then you can cut create a comma-separated list of these row numbers. So if while I want to say that the task in row 7 can't be done until the tasks in row 6 + Row 2 can't be done then I would enter it this way.

If I switch to the graph view any changes and that I make in the sheet you will also update the graph view so this is what the precedence looks like based on the edits that I made in the sheet.

You now see that I want to connect this activity to a different activity it is a predecessor to a different activity. So as long as I'm in edit mode I'm going to click in the middle of the task tile and holding the mouse down, I'm going to drag an arrow into the task successor. When I let go, those two tasks are now connected.

If I want to delete a precedence line then I can simply click on that line, hit the Delete key on the keyboard and I've removed the precedence constraint. If you make changes to the graph view and then you want you can click on the auto layout button and it will adjust and I'll lay out the precedence network cleanly again for you.

If you switch to the zoom mode which you can do by clicking on the toolbar or you can right-click and select zoom, you can switch between the edit the zoom in the pan modes. With the zoom, you can select an area and it will zoom in on that you can also use your mouse scroll bar if you have one to zoom in and to zoom out. If you switch to pan mode then you can grab the graph and drag it along okay but anytime you want to add or remove precedence lines you want to make sure that you're in the edit mode.

Whatever precedents that you define here in this graph tab will be used in the line down scenario whether you manually move tasks or use the default balance to automatically rebalance the line. If you manually move tasks you will be allowed to violate essence but in this scenario, you will be shown constraint violations to let you know that you have violated your precedence and if you run a default balance precedence will never be violated so while there are other constraints like monumental resource and works own constraints that you can choose to turn on or off precedence will always be followed.

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