I'm going to float over pmp!. The difference between the total float time TF and the free float time FF is!!!!!!!

This article references the http://blog.sina.com.cn/s/blog_ae72ef760101bxhz.html
With two pictures in it.

First of all, we put the project Progress Network Diagram of our example:

What are some of the numbers in each of these small squares mean:

TF = Total Flow = Overall float time
FF = Free Flow = freely floating time
Each small block is an activity, and both TF and FF are free-floating times for an activity

The amount of time that a progress activity can be postponed without delaying the earliest start date of its tight schedule activity.

Explaining the word "delayed" in the official definition above, I was beginning to wonder if this delay was the first time to postpone the start or the latest start time, but to think about it, our ideal schedule must have been calculated by the earliest start and the earliest end of the activity, So if an activity is postponed, it must have been postponed compared to the earliest event start time.

For example, the activity F, it will end at the earliest 15 weeks, and its tight after the activity of H, because the start of H not only depends on F, but also depends on the completion of other activities, so H will start from 17 weeks, that is, f activity as long as 17 weeks prior to completion will not affect the activity of H, If the F activity is completed in an optimistic estimate of 15 weeks, then the idle 16th Week is the free float of f activity, so the free float time of F is one week.

Now look back to the official explanation, is not clear enough, remember that the free float time with two "earliest" to calculate, tight after the earliest start time of activity minus the early end of the pre-activity time.

The actual floating time of the pre-activity is within the free-floating time range without any effect on the tight post-activity or the project.

Well, then, if the F-activity actually floats for 2 weeks, more than 1 weeks, you'll find that even if f has been floating for two weeks from the earliest start time, it should have ended in 15 weeks, and now ends in 17 weeks, it will only lead to H activity starting from 18 weeks and ending in week 22nd, There is also no early start date to the final activity I, so the total project duration will not be affected.

If the actual floating time of f continues to grow larger, it will always affect the total duration of the time, then how much floating would affect the overall duration.

It's time to talk about the total float. Total float Time

The total amount of time that a progress activity can be postponed without delaying the project completion date or violating the schedule constraints.

Each activity on the chart has the latest start time, all said is the most the most late start time, meaning is again late to a big problem, so the total floating time is an activity of the latest start time minus the earliest start time, with the latest end time minus the earliest end time is the same ha. Over this time, the project must be delayed (according to the original plan ha, here does not consider the rush and fast follow-up ha). Summary

Free floating time = The earliest start time of the following activity-the earliest end time of this activity
Total floating time = own late start time-own earliest end time

If an activity is delayed (why not consider the early completion of the activity, this good situation does not have to consider ha)
<= free float Time: No impact, no impact on tight after activities according to our best plan to start, also certainly does not affect the total duration

> Free float time and <= total float time: Tight after the activity is delayed, but fortunately, will not affect the total duration

> Total float time: Break the fire, the duration is not guaranteed

Back to the top of the Progress Network diagram, the red line is the critical path, in general, each activity of the critical path is not the total floating time and free floating time (special case not discussed here), because it is the most critical path, so any one of the activities of any delay is considered to affect the duration.