Boolean Modifier Dissapearing When I apply a Boolean modifier to say a cube during an animation and link a cylinder as the Boolean object and animate the cylinder going through it, when the cylinder goes all the way through the Boolean modifier disappears on the cube and it becomes solid again, is it possible to make the cube contain the hole through it after the cylinder has passed through it. I have tried the carve feature instead and it still doesn't work. Any help is appreciated, thanks.
For animaton you need to create keyframes, that are inserting by pressing I. Creating or removing smf are not a operation that can be keyframed. 

Instead of this try to animate displaying of modifier. So do the following:


Go to the 1 frame
Hover cursor on eye icon  and/or camera icon and press I
Go to a frame that you want to hide modifier 
Disable modifier (eye icon disables in viewport, camera - in render)
Hover cursor on eye icon  and/or camera icon and press I




It will create an animation, that will hide modifier after chosen frame

For creating a hole, I recommend to create a copy of cylinder, that will not leave a cube, and make them invisible for render:



You can do it in outliner.