2017LHPscrewball posted:Can someone explain the exact process of "rolling" and what it does to the structure of the metal? My understanding was that "rolling" was sort of a break-in process and a similar effect would eventually be had after enough hits. Does "rolling" impair the metal structure such that it is more apt to break apart?
As for shaving, once the problem is big enough I suspect someone will figure out how to make the cap tamper proof as part of the certification (of course someone will come along and figure out how to tamper without getting caught).
Rolling does nothing for a metal bat. Rolling is used on composite bats and provides a quicker and more even break in than natural hitting does. There is a break in period for composite barrel bats where the bat gains more of its trampoline effect as the fibers relax. The same identical effect occurs as you hit balls with a composite bat, however it won't necessarily be even, and can take several hundred hits to hit a bats max output. Studies show that after about 500 hit, the bat actually begins to diminish in performance. Rolling will allow bat to reach peak performance immediately, but will also shorten the life of the bats performance overall, however the time at peak performance would be the same as a bat "naturally" broken in.
One of the BBCOR measurements required that companies meet the criteria with the bat broken in, so that the bat cannot exceed the standard as its performance peaks.
Shaving does affect metal bats as it simply allows the bat to have a greater trampoline effect (thinner walls, more flex). It also makes the bats more prone to premature failure.
Here's some rather dated info from a Penn State study.