What is static electricity?
Static electricity is a natural process in which electrical charge builds up between materials until it finds an escape route and discharges.
Atoms tend to seek a balance between protons and electrons (balanced charge), but sometimes imbalances can occur:
- Positive charge: When an atom loses an electron, positive ions are generated, producing a positive charge.
- Negative charge: When an atom gains an electron, negative ions are generated, producing a negative charge.
These imbalances create electrostatic charges that can negatively impact industrial processes.
How is static electricity generated in industrial environments?
Static electricity naturally arises in all industrial processes, where there is a transfer or a gain of electrons between materials, resulting in the generation of an electrostatic charge:
Charge generation by contact and separation:
For example, a cylinder continuously impacting a material can produce a positive charge on one element and a negative charge on the other.
Charging by friction:
Industrial processes like conveyor belts or material movement over rollers are typical examples of how friction can generate static electricity.
External influence:
In instances where a charged object, even without direct contact, induces charge in another body simply through proximity, it creates an imbalance of charges within the element itself. This holds particular significance in the electronics industry due to the sensitivity of electronic components to extremely low potential discharges.
Electrostatic charging by blowing:
In cleaning applications that involve blowing, it's essential to pre-treat the compressed air by filtering it to remove contaminating particles and drying it to prevent condensation on the part being cleaned.
Lack of humidity causes the air to become more insulating, potentially leading to the generation of an electrostatic charge on the surfaces where blowing is directed.
What are the risks of static electricity in industrial settings?
Static electricity poses significant risks to the overall efficiency of industrial machinery and processes, known as OEE (Overall Equipment Effectiveness).
OEE evaluates machine availability, process performance, and product quality, where static-related issues impact each parameter differently:
Machine availability:
Electrostatic charges produce forces of attraction or repulsion between materials, leading to line jams and subsequent unscheduled stops, thus impacting machine availability.
Process performance:
It is sometimes necessary to reduce machine speed to minimise static charge generation, thus compromising cycle times.
Product quality:
Static charge results in dust adherence, contaminant attraction, and electronic component damage, affecting final product quality and increasing rejection rates.
Availability and performance are related to macroscopic statics, mainly associated with industrial processes involving the transport and handling of plastics and polymers.
Some problems associated with macroscopic statics include:
- Defective welding and cutting
- Jams in winding machines
- Part feeder jams
- Defects in shrink wraps
- Incorrect handling
On the other hand, quality is related to microscopic statics, associated with industrial processes related to electronic parts, semiconductors and components in the automotive industry, where surface cleanliness is a critical aspect.
Some incidents linked to microscopic static include, for example:
- Pores in painting processes
- Contamination of plastic products
- Defects in injection moulds
- Breakage of brittle materials
- Electrostatic discharge (ESD): irreparable damage to electronic components or latent damage to electronic components that impairs their service life.
Both macroscopic and microscopic static can negatively affect industrial processes across sectors or industries, as well as product quality and industrial safety. Operators could be affected by electrostatic discharges (ESD), and an excess of charge could even trigger fires or severe accidents, impacting workplace safety.
How to control and eliminate static electricity in industrial processes?
Solutions for controlling static electricity can be classified as follows:
Measurement systems:
Identifying critical points and eliminating electrostatic charges begins with measurement. Utilising sensors, like SMC's static electricity sensors, is the first step in combating this invisible enemy.
Grounding:
Preventing electrostatic discharges that affect workers involves proper grounding. Ensuring all conductive materials have a grounding connection evacuates the generated electrostatic charge and prevents the passage of electric current from devices to users.
Static control and elimination systems:
There are different types of ionisers or static electricity eliminators:
These types of static eliminators are usually used on larger surfaces and for longer ranges.
Ionizing nozzles are usually suitable for neutralising static energy on more specific surfaces.
Ionizer fans are often used to cover a larger working areas or spaces without access to compressed air.
Ionizing air guns are used for manual cleaning of insulating materials to prevent the static charge from causing particles to adhere to the surface.
Anti-static components:
Considering the material of auxiliary components is vital in controlling static electricity in industrial processes. For example, anti-static pneumatic connections for blowers or, in the case of vacuum applications, anti-static suction cups that are designed to minimise and dissipate the charge generated.
Industrial technical cleaning:
When the presence of statically adhered particles negatively impacts product quality, it is advisable to carry out an industrial technical cleaning of the surfaces. SMC offers duster boxes capable of neutralising static electricity, eliminating and collecting dust in a single unit. These can be used in clean rooms.
Simplicity and efficiency: that is the motto of SMC's range of antistatic solutions.
With our antistatic solutions, you can optimise the performance and quality of your industrial processes, thanks to the ease of installation and maintenance of our static electricity meters and eliminators.
Find the right ioniser to avoid unplanned shutdowns, resolve quality concerns in your final product, and safeguard operators from discharges.
Do you need guidance on selecting static electricity sensors or eliminators? Consult our specialists in electrostatic charge control and neutralisation for expert advice.
