About Static


Custom Design Services

What You Need To Know About Static

FLX-P Flexible Antistatic Brush

How is static generated?

Friction, pressure and separation are the major causes of static electricity. This process is called the Triboelectric Effect ("tribo" means rubbing). The triboelectric effect is responsible for the shock you receive from a car door after you slide out.

The magnitude of the static charge is determined by material composition, applied forces, separation rate, and relative humidity. These factors conspire to cause conveying mechanisms, and other systems, to act as static generators. Even slow-moving conveying mechanisms are capable of generating ample static charge to cause an ESD ( Electrostatic Discharge ) event. An uncontrolled ESD event can generate enough EMI to damage electronic components.

Environmental variables like relative humidity influence the level of electrostatic charges. When humidity is low, higher static charges are generated (see Table I). Static becomes more noticeable in the winter months, in dry climates, and in air conditioned environments. Increasing humidity to 60% limits static build-up because surface moisture on materials makes a good conductor. Unfortunately, 60% relative humidity is extremely uncomfortable, can cause equipment problems and introduce contaminants into your system.

Fortunately, static control devices can be located at critical points to control the ESD event by reducing the static charge to low levels. Static Control devices allow smoother operation of conveying mechanisms and eliminate electronic component damage caused by ESD events.

Friction
Pressure

The Triboelectric effect is the major cause of static - the greater the force of friction or pressure, the more static will be created. Also, faster rates of separation cause more static.

Table 1: Typical Electrostatic Voltage
 
Electrostatic Voltages
Means of Static Generation
10-20 percent Relative Humidity
65-90 percent Relative Humidity
Walking across carpet
35,000
1,500
Walking over vinyl floor
12,000
250
Worker at bench
6,000
100
Vinyl envelopes for work instructions
7,000
600
Common poly bag picked up from bench
20,000
1,200

Static Control Devices

FLX-P Flexible Antistatic Brush

EST static control devices work by induction; much like a lightning rod. Physical contact between the static dissipative brush and the target material is not necessary. The electric field created by the static charge is concentrated at the fibers sharp points. Once the electric field exceeds the breakdown strength of air, the air molecules will be ionized and the charges are transferred to the brush and then to ground.

For more information on static control, join a live training webinar on Static Charge Generation and Mitigation.  Click here to sign up. Our Sales/Engineering Support team will schedule a time that is convenient for you.