Perhaps you have seen the blue or pink foam boards used to insulate anything from basement walls to garage doors, to walk-in freezers. The stuff is used everywhere in building trades and for any application that requires a great deal of insulating value from a rather thin piece of material.
One of our customers manufactures these foam boards and was having a good deal of difficulty with static electricity within the process. The static electricity in this process was being generated between the Polystyrene board and the Teflon sheet used to create the smooth finish within the calibrator section of the extruding process.
Specifically, the static field was forming where the Teflon sheet peeled away from the material. Whenever you separate two insulating materials which are in contact with one another, an amount of static will form at this point. In this application, the resulting problem was that the conveyor drives did not have enough power to overcome the friction created by a meter wide foam board providing resistance to the flow of the material through the die. Also, operators received frequent static shocks from the material if they even came close to the side of the process.
In the video, you will see the actual extrusion process with the calibration die which has the white Teflon sheet. The Super Ion Air Knife was not installed at the time the video was taken, but it gives a good perspective of what the customer has to deal with.
Once the customer installed (2) model 111242 (42” Super Ion Air Knife kits) where the blue foam exits (one for top and one for bottom), the conveyor drives no longer had problems moving the material and the operators were safe to come into close proximity to observe.
Sheets of fiberglass, polypropylene, ABS and other polymers are extruded into sheet form in a similar way. In the past we have solved other similar static issues when the process involves a “carrier” type of material to set the surface of the extruded material and subsequently removed by a peeling action.