static electricity - aimcal · 2018-10-08 · problems with static electricity in the converting...
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Product shown in this document may be covered by one or more patents, patents applied for and/or registered designs and/or trade marks. For further information please refer to our Head Office or visit www.meech.com.
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Static Electricity: Causes and Cures in Web Converting
Presented By: Matt Fyffe
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What is Static Electricity?
Electrical imbalance of charge can exist on insulators & isolated conductors.
Insulator Isolated Conductor
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What Causes Static?
Friction between materials:
Separation of materials:
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Not +ve or –ve... but size does matter!
The Polarity of the charge is not very important. You can not tell the difference.
It is the size of the static charge that is important. The larger the charge the greater the problem it will cause.
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Force/Speed – faster, harder processes increase the charge
Repetition – causes further build-up
Heat - heating and cooling can leave an object charged
Humidity – low humidity allows high charges to remain for long periods
Type of Material – some materials charge very easily (i.e.: PVC film)
What factors affect the size?
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Triboelectric Series
Materials above the arrow will naturally charge positive. The materials below the arrow will naturally charge negative.
When contact and friction is generated between different materials the central point shown by the arrow may change relevant to the type of materials
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Triboelectric Series
This example shows polyester film contacting a silicon coated roller.
When measured immediately before and after the silicon roller the negative charge on the polyester will reduce or change to positive.
Polyester Film
Silicon coated roller
( + )
( - )
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Problems with static electricity in the converting industries are numerous.
Processes where static can be an issue include film sheeting and slitting, wind and rewind stations as well as printing.
The primary problems resulting from high static charge are:
Process Control and Quality Problems Dust Attraction and Contamination Operator/Personnel Shocks Possible Fires and Explosions
Problems Caused by Static in Industry
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Passive Eliminators
Nuclear Eliminators – Polonium 210
AC Eliminators
Pulsed DC Eliminators
…and Static Generation
Methods of Elimination
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Passive Eliminators
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Nuclear Eliminators – Polonium 210
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AC Eliminators
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Pulsed DC Eliminators (Mid & Long Range)
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Passive EliminatorsAdvantages Disadvantages
Low Cost Limited CapabilitiesNo External Power Source Wear Part/Flaking
Low Maintenance
Nuclear Eliminators - Polonium 210Advantages Disadvantages
Perfectly Balanced Annual Lease/CostIdeal for Hazardous Locations Paperwork Requirements
No External Power SourceLow MaintenanceEase of Installation
AC EliminatorsAdvantages Disadvantages
Low Cost Limited Range w/o AirPower/Performance Limited Load CapabilityEase of Installation Maintenance Required
Multiple Bars on Power Supply
Pulsed DC EliminatorsAdvantages Disadvantages
Long Range w/o Air Requires EducationReliability Longer Set Up
Low Maintenance Increased CostAdjustability/Customization
Feedback CapabilitiesInternal or External Power Supply
Very Flexible
Static Eliminators - Comparison
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Operating Distances
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Compressed Air Driven Static Control
Close Range Static Control
Mid Range Static Control
Long Range Static Control
Pulsed DC Nozzle AC Air Curtain Standard AC Bar Long-Range AC Bar Mid Range DC Bar Pulsed
DC Bar DC Bar with Air Boost AC Blower
60”
56”
52”
48”
- Install at optimal distance where
possible
44”
40”
36”
32”
28”
24”
20”
16”
12”
8”
4”
1 ¼”-
2” 2”
0 0 – 6” 0 – 6” 1” – 4” 1.25” – 6” 2” – 20” 6” - 30” 12” – 48” 8” – 60”
* Not to scale. Actual positioning will depend on the type of application.
Compressed Air Driven Static Control
Close Range Static Control
Mid Range Static Control
Long Range Static Control
Pulsed
DC Nozzle AC Air Curtain Standard AC Bar Long-Range AC Bar Mid Range DC BarPulsed
DC Bar
DC Bar with Air Boost
AC Blower
60”
56”
52”
48”
-Install at optimal distance where
possible
44”
40”
36”
32”
28”
24”
20”
16”
12”
8”
4”
1 ¼”-
2”
(-) 2”
0
0 – 6” 0 – 6” 1” – 4”1.25” – 6”2” – 20”6” - 30”12” – 48”8” – 60”
* Not to scale. Actual positioning will depend on the type of application.
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Positioning Free air is required on opposite sides of the target
material, not a roller or solid object
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Positioning Avoid proximity to grounded parts of machinery as this
will distort the corona and reduce its efficiency
If bars are needed on both sides of the material, they should be staggered
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Measuring Static Meters – measure actual surface charge
Ion Sensors – maintenance tools for testing ionizers
Charge Decay Monitors – measure decay times of ionizers Benchtop & Handheld
Surface Resistance Meters – measure capability to hold a charge
AC Sensor Pen – down and dirty way to test for voltage
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Applications
Winding – Short Range
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Applications
Winding – Mid Range
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Applications
Winding – Long Range
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Applications
Turret Winder
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Applications
Slitting
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Applications
Laminating
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Applications
Coating
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Static Generation
Static generation describes a method for creating a controlled static charge on a non-conductive material that will allow a sound, but temporary adhesion between surfaces with charges of opposite polarity.
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Applications
Static Generation – Film on to Roll Cores
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Applications
Static Generation – Sheet Lamination
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Web Cleaning Systems
Web cleaning systems provide effective solutions to problems such as:
Dirty webs causing loss of profit and customer dissatisfaction
Excessive downtime on printing presses
Frequent blanket washing
High reject rates in laminating or coating processes
Unacceptable quality in pharmaceutical or food packaging
Poor print quality
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Web Cleaning Systems
Tacky Roll Cleaner
Contact Web Cleaner
Non Contact Web Cleaner
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Tacky Roll Contact Web Cleaners
Elastomer cleaning rollers contact the full width of the web with even pressure. Dry, unbonded contamination is lifted from the web surface.
Pneumatics hold the adhesive roller in contact with the elastomer roller. Contamination is transferred from the surface of the elastomer roller to the adhesive roller where it is trapped.
Any static charge present on the web is neutralised on exit from the web cleaner; minimising the risk of statically attracted recontamination.
How it works
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Vacuum Based Contact Web Cleaners
Static NeutralizationBreaks the bond between dust particles and web, leaving the web neutral after cleaning.
Breaking boundary layerBrushes destroy boundary layer on fast movingwebs and dislodge any physically attached particles.
Powerful VacuumExtremely high speed airflow through faceplate is very turbulent. The turbulence allows removal of very small particles.
How it works
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Non-Contact Web CleanersHow it works The web passes through a cloud of ionization on entry to the cleaning, which neutralizes any
static charges.
The web is then subject to a force of turbulent air created by the blowing and vacuum airflows within the head unit.
High frequency micro-movements of the web are created by the turbulent air.
The combination of the high frequency micro-movements and turbulent air shatters the webboundary air layer, releasing the contamination into the vacuum airflows.
As the web exits the head, it passes through a second cloud of ionization to prevent re-contamination of the web.
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Web Cleaners - ComparisonTacky Roll Contact System
Advantages DisadvantagesLow Cost 750'/min max speed
Proven to 0.5 micron Not suited for heavy contaminationCompact Size Ongoing consumable costEase of install
Suitable for sensitive materials
Vacuum Based Contact SystemAdvantages Disadvantages
Excellent for high contamination Not suitable for sensitive materialsSuited for high speed applications Requires installation space for fan
Suited for paper and boardEase of installation
Proven to 5 micron cleaningSuitable for wide webs
Non-Contact SystemAdvantages Disadvantages
Suitable for all materials Double sided onlyProven to 0.5 micron 120" max web width
Compact size Ducting requirementsLow and high end applications Initial Installation Time
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Thank you
www.meech.com
http://www.meech.com/
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