by Julian Joffe, Engineered Printing Solutions
We all have experienced the effect of static electricity in our lives. From rubbing a balloon on a sweater and sticking it on a wall, to receiving the zap from someone who’s shuffling their feet across the carpet, it is a very real force that certainly can affect pad printing.
Like the electrical discharge after rubbing a balloon on your hair, static electricity can cause ink to discharge from the pad before it makes contact with the substrate. Static can build on the pad by its simple movement when relative humidity falls below 30 percent.
Printing problems manifest as spider hairs or spider webbing radiating from the artwork edges, or other loss of image resolution.
Possible causes of static in the work environment are atmosphere or materials.
Atmosphere
Low humidity and temperature, especially in winter conditions (or in western states, such as Nevada and Arizona, which suffer chronic static) combined with artificial heating, are the primary culprits of static-caused image resolution issues.
Here’s how to fight back:
- Install a thermometer and hygrometer in close proximity to your equipment. Maintain optimum temperature and humidity levels based on their readings.
- Increase the humidity level in the air to at least 40 percent.
- Run inks a little thinner than normal.
- Add anti-static paste to your ink.
- Use an ionized air blower or nozzle directed at the part fixture.
- Use pads with aluminum bases and electrically “ground” the pad base to the machine.
- On wood base pads, “ground” the pad to the machine. This is done by inserting one end of electrical wire into the pad, near the base and the other end to the machine, making sure the wire is long enough to allow full pad cylinder extension.
Materials
Parts can become electrically charged in manufacture, packing, shipping and storage. Certain materials, such as polycarbonates, acrylics and strenes, are more prone to static buildup.
To prevent a static-caused electrical charge:
- Do not allow parts to come within the effective range of static-generating equipment like electric motors, fans, etc.
- Unpack parts and place in a metal container. Ground the container to allow dissipation of any static charges.
- Use an ionized air blower or nozzle directed at the part fixture.
- If the part fixture is metallic, this too can be grounded to help dissipate static charge.
Engineered Printing Solutions, formerly known as Pad Print Machinery of Vermont, is headquartered in East Dorset, Vermont. For more information, or recommendations for permanent resolutions to persistent static electricity problems, call 800.272.7764 or visit www.epsvt.com.
Reprinted with permission.
