I assume that all of us having the static problem on the folder make some effort to wind the stock as we build the pile on the feeder and this relates to the pile turner with aerator, but would be a difference of degree.
Have those of you with the problem noticed a significant difference with press loads that have sat over the weekend before loading on the folder? This would bear on the question as to wether the severe static is coming from the press (and dissipates over the weekend), or is being generated on the folder itself as each sheet is pulled from the top of the pile by the vacuum wheel while the sheet hold downs at the tail cause a rubbing action of the top sheet with the rest of the sheets in the pile, thus generating some static right at the folder feeder.
Also have you noticed that the problem is significantly worse with piles coming from presses with heaters in the delivery as compared with piles from presses without that? In the case of pile from presses with heaters, the press delivery piles that sit over the weekend have a chance to regain some of the moisture lost in the press delivery due to the heaters, and this may explain the difference of degree of the static problem on the folder for piles that have sat over the weekend.
What about a difference in speed at the folder? Often stock that feeds fine at moderate speeds will start to pick up doubles when the folder speed is increased beyond say 12,000 sph. no matter what combination of suckers or degree of separator brush interference is used. This may be explained by the rubbing action at the hold downs mentioned earlier. In this regard, is there anyone reading this using with marked improvement In-Air-Line anti static devices for the air blowers at the tail of the sheet in pile fed folders?
It seems to me that if only we could completely eliminate the static problems, we could run our folders at 16 - 20 M sph. The StopStatic products mentioned by DrummondAW look interesting.
Please report your experiences with any of these issues.
Thanks,
Al Ferrari