Find Sources of Static Charging
- Published: March 19, 2012, By Kelly Robinson
Electrostatic fieldmeters are often used to make relative measurements. Is static high or low? Is static near the winder higher today than last week? Relative measurements are important and they are valuable tools for controlling static.
Making quantitative measurements enables us to identify sources of static charge and to measure the amount of charge deposited on the web. To do this, measure the electrostatic field just before and just after a conveyance element. Use the “rule of thumb” that an electric field of 1 KV/cm results from a charge density of 1 mC/m2. So, a source of charging will cause an increase in the measured field.
Using this method, the most common source of charging that I have found are:
|
Source |
|
Charge Level |
||
|
: |
10 mC/m2 |
- |
50 mC/m2 |
|
|
: |
0 mC/m2 |
- |
20 mC/m2 |
|
|
: |
10 mC/m2 |
- |
20 mC/m2 |
|
|
: |
5 mC/m2 |
- |
15 mC/m2 |
|
|
Bowed Rollers |
: |
2 mC/m2 |
- |
10 mC/m2 |
|
Spreader Rollers |
: |
2 mC/m2 |
- |
10 mC/m2 |
|
High Traction Roller |
: |
2 mC/m2 |
- |
5 mC/m2 |
|
Metal Conveyance Rollers |
: |
0 mC/m2 |
- |
1 mC/m2 |
At the Society of Plastics Engineers (SPE) Annual Technical Conference (ANTEC) held with the National Plastics Exhibition (NPE) in Orlando FL, April 2-4, 2012, my presentation “Static Charge Control for Plastic Webs in Roll-to-Roll Manufacturing Processes” discussed how to identify sources of charging, to determine how much charge is deposited on the web, and where to put static dissipaters to neutralize the charge.
