Principles of Static Creation and Dissipation

The friction of two materials rubbing against each other causes the "triboelectric" phenomenon known as static charge. In equipment, static buildup often is seen in conveyors and web presses. A conveying system may generate significant amounts of static electricity. If the static electricity does not have a grounded path to follow it can lead to an ESD (Electro Static Discharge). An uncontrolled ESD occurrence can, in turn, cause short circuiting of electronic components, induce a fire or cause difficulties in moving material (paper, plastic sheeting etc.) through a piece of equipment.

Environmental variables such as relative humidity influence the level of electro static charges. When humidity is low, higher static charges will typically be generated. For this reason, static becomes more noticeable in the winter months, in dry climates, and if air-conditioning is used.

Raising humidity to reduce static charges

One method to decrease the presence of static electricity is to increase relative humidity. By increasing the humidity to 60% in the area surrounding the static build-up you will reduce the opportunity for uncontrolled ESD. Surface moisture on materials will act as a conductor. This 'solution' of relative humidity is however extremely uncomfortable, can cause equipment problems and introduce biological contaminants into your equipment.

Using a static control brush to eliminate ESD

As an effective alternative, a custom static control brush can be simply engineered to control or eliminate an ESD. Static control brushes allow conveyors to run more efficiently and avoid the mis-feeding of paper as well as the contamination of plastic films caused by charged particles "sticking" to plastic moving through a conveyor mechanism. Of course, a properly placed static control brush will also help to prevent electronic component damage caused by ESD.

Proper placement of the static control brush

Static control brushes work by induction, much like a lightning rod. Physical contact between the static eliminator brush and the target material is not necessary. Putting static control brushes in very close proximity with the material being moved will provide a path to ground thereby neutralizing a static charge. Your static control brush should be positioned inside the equipment at a point after the static charge has been created. Proper positioning provides the ESD static dissipation capability prior to any static-induced problem within the machine. To work effectively, your static control brush must be grounded.

Please call or email us for help designing a system to eliminate static that is right for your application. If you would like to purchase stock dimension static brushes please contact websales@westmontinc.com

For smaller quantities of stock brushes visit McMaster Carr.