Porosity enhancement by the utilization of screening patterns in electro-perforated paper webs

Effect of the Electric Discharge Confinement on the Perforation Density of Porous Materials

“…The dimensions of the perforations may depend on several factors such as the type of web material (density, thickness, intrinsic porosity), spark energy, electrode geometry, etc., and are normally in the range of a few hundreds of micrometers. The separation between the electrodes plays a major role in the maximum perforation density that can be achieved [1]. This parameter also affects the spread of the perforations track over the running web.…”

“…This parameter also affects the spread of the perforations track over the running web. An obvious action to reduce the attractor effect [1] caused by the already made holes is to decrease the distance between the electrode tips. However, this is a critical parameter that in general cannot be reduced without putting at risk the integrity of the web material.…”

“…The spark discharge process fundamentally consists in the following sequence of events: first the formation of a precursor channel of ionized air between electrodes and subsequently, the sudden triggering of an electron avalanche travelling from the cathode to the anode in a self-propagating streamer. This fl w of energetic electrons generates microperforations in thin porous materials such as paper, plastic, biological membranes [1]. The firs spark creates a hole in the paper randomly located inside a circular region centered on the electrode axis.…”

“…In this paper, it is shown that the effective distances between the perforations can be reduced by introducing a pierced matrix in-between the electrodes. This matrix is capable of limiting the lateral excursion of the electric discharge thus increasing the porosity of the material [1]. However, despite the benefits the introduction of elements between the electrodes in industrial environments presents serious drawbacks.…”

Method for improving the electrostatics perforation pattern using power controlled discharges

“…In previous work [2], the authors have investigated the relationship between the electrode distance and the perforation density and defined the drag distance as the minimum separation needed to generate a second hole in a specific area.…”