Laser wire stripping is the process of removing all or part of the insulating material that covers electrical cables. In other words, it is the process used to uncover the metal core of the cables. It is typically done at the cable’s ends to make connections possible, but it can also be done in various ways along the cable.

Laser stripping’s main feature is that the laser selectively intervenes on the insulating material without affecting the cable’s metal core. This is a significant advantage over traditional stripping techniques. The high quality and precision of the laser striping process has made it a widely used technique in high-tech sectors.

Not surprisingly, the idea of ​​using lasers to remove the insulating layer of electrical cables was born in the aerospace sector. In the 1970s, NASA needed to find a solution to strip the thin Space Shuttle cables. The stripping tools used at the time did not guarantee the quality and precision necessary for an application of that type.

Traditional wire stripping methods and their drawbacks

The first is the mechanical method, which is the most widespread. In this process, blades are used to cut the electrical cables’ sheathing.

This method has many drawbacks:

• to achieve accurate results, the process becomes extremely slow
• each type of cable requires a dedicated tool
• the tools require maintenance to remain effective

The risk of damage, for example notching the cable, is one of the main risks of this technique. To solve this problem, manufacturers have produced oversized cables, so that any loss of metal would not reduce the functionality of the cable.

While this may be a solution for low-tech industries, oversizing cables is not a suitable solution for others.

In the aerospace sector, for example, weight containment is essential. Cables are designed to be very thin so that they weigh as little as possible. This means that any damage to the cable could cause it to malfunction and lead to accidents.

In addition to the mechanical method, peeling can be performed with a chemical or a thermal process.

The chemical process uses corrosive substances such as sulfuric acid to dissolve the cable coating and expose the conductive material. The disadvantage of this technique is that it is not easily controlled and is also polluting.

The thermal process uses a heat source to remove the coating. This method, however, can leave residual coating material on the metal core which would therefore have to be subjected to further processing.

Laser stripping overcomes all the previously mentioned drawbacks. It is therefore not surprising that it has established itself as the method of choice for high-tech applications.

Why laser stripping works

In most cases, the material that coats electrical cables is some kind of plastic polymer while the internal core is made of metal, very often copper. Laser technology has the ability to select only the coating’s polymers without modifying the conductor in any way.

This behaviour can be explained by the way laser radiation interacts differently with different materials.

CO2 laser emits radiation at a wavelength of 10.6 micrometers, that is, in the far infrared [far-IR] region. Polymers absorb this radiation very well while copper reflects it almost completely, without undergoing alterations.

The advantages of laser stripping

Laser stripping offers several advantages over traditional methods:

• flexibility: it is effective on almost all polymeric materials with which electrical cables are coated
• precision: it is a non-contact process, which makes it able to work on very tight tolerances and to carry out processes that would be impossible with traditional methods
• effectiveness: since laser is reflected by most metals, the process ends with the removal of the polymer without requiring any further processing

What are the different types of laser stripping

In laser stripping, the laser can perform 3 basic operations:

• laser cross cutting: the cut is carried out transversely to the cable in order to allow the removal of excess material
• laser slitting: the cut is made lengthwise. Typically this process is performed when a longer portion of cable needs to be removed and is used in conjunction with the cross cut
• laser ablation: the laser passes over the surface several times until the coating is completely eliminated. This technique is mainly used when the conductive material is immersed in the coating (otherwise known as bonded wire).

Alongside these basic operations, laser technology makes it possible to perform advanced processes such as the partial and targeted removal of the coating with the creation of windows or the removal following certain patterns. All these applications can’t be done with traditional mechanical methods.

As is often the case with lasers, the possibilities are endless.

How a laser stripping system is made

A laser cable stripping system can be implemented in various ways and with various technologies.

The most effective is certainly galvo-scanning. In this application, a scanning head is used to move the laser beam and then focus it on the work surface.

The whole system is controlled by a computer which coordinates the operation of the CO2 laser source allowing the laser to follow the pre-defined cutting path.

Implement your own laser wire stripping

Laser cable stripping lends itself to many applications. It is ideal for high-tech sectors that require great precision during the processing phase. One of the applications, for instance, is magnet wire stripping with laser.

Don’t hesitate to contact us. Our staff would be happy to advise you on the best laser solution for your needs.

In recent decades, lasers have become a widely used processing tool. Its role as a production tool is increasingly established, both in traditional applications such as laser cutting, laser welding or laser marking, and in more advanced ones such as laser paint removal, laser surface treatment or laser microperforation.

The success of this tool is due to the advantages it offers in terms of process flexibility. The same laser source can be used to perform different processes such as cutting and marking on different materials such as plastic and wood, even within the same operating cycle.

This great flexibility translates into process complexity. In general the working mechanism of the laser is very simple. A laser is a light source capable of concentrating a very high energy density, so much so that it can be used as a heat source. In practice yet, the interaction between the laser and the material is influenced by numerous factors that make it very complex.

Conceptually, cutting, drilling, engraving and marking share the same processing mechanism: laser energy is used to create chemical and physical transformations in the material. These transformations can range from the simple colouring of the material, as is the case with laser marking, to the complete removal of the material by sublimation as is the case with laser cutting. In order to switch from one process to another, it is sufficient to modify the laser parameters using the appropriate control software.

For this reason, each application must be studied according to the characteristics, of the laser, of the process and of the material.

In this article we will analyse the main parameters that come into play in laser processing, with particular reference to the CO2 laser.

Laser-related parameters

Unlike traditional production tools, laser technology has a wide range of configuration options. Each parameter affects the end result of the process and must therefore be configured appropriately according to the desired result on the material.

The laser parameters to pay attention to are:

• laser source power
• beam spatial mode
• beam temporal mode
• laser wavelength
• beam polarisation

Laser source power

The power of the laser source is a very important parameter. It regulates the laser’s processing speed and the depth of the engraving. The more powerful the laser, the greater the amount of processed material in the same amount of time. Furthermore, the more powerful the laser, the thicker the material that the laser will cut can be,although, as we will see further on, this parameter depends in part on the characteristics of the material.

If you are using a low-power laser, it may not be possible to cut a material from side to side. On the other hand, a laser with a higher power than the one needed to carry out a specific process, can cut through the material, with the risk of obtaining a lower quality cut, with burnt and uneven edges due to the slag produced by the excessive power of the laser.

As a general rule, the choice of the power of a laser source should be made in excess so that the power can be lowered until the desired result is obtained.

Spatial mode of the laser beam

This parameter defines the cross-sectional profile of the laser beam. A laser beam can have several modes, i.e. it can have different profiles.

The most commonly used mode in laser cutting applications is the Gaussian mode, as it allows maximum energy density to be produced, i.e. the beam is concentrated in a very small diameter point.

In this way, it is possible to obtain cuts and engravings with very reduced dimensions, with high processing speeds and the possibility of cutting larger thicknesses.

Other spatial modes, on the other hand, allow the beam to be focused on a larger surface area, thereby achieving lower energy densities.

Time mode of the laser beam

Lasers can be used in two modes, continuous wave or pulsed mode. The continuous wave mode is the most widely used (mainly in mass production), and allows very smooth cuts and thicker materials to be cut. The pulsed mode is used for more precise work, often with a low-power laser.

Wavelength

The way different materials absorb laser radiation depends on their wavelength. While some materials absorb the wavelength of the CO2 laser very well, others require different wavelengths and therefore other types of laser.

Aluminium and copper, for example, absorb the wavelength of the CO2 laser very little and require very high powers to be cut, which reduces production efficiency. Non-metallic materials such as wood and synthetic materials such as polymer plastics, on the other hand, absorb the CO2 laser radiation perfectly. Metals such as mild steel and stainless steel can also be cut with the CO2 laser with excellent results.

Polarisation

Polarisation refers to the ability of the laser beam to radiate in only one direction. This property differentiates the laser from non-polarised light sources, which radiate in all directions.

This parameter is important insofar as it affects certain characteristics of the cut. Generally speaking, when the cutting direction and polarisation have the same orientation, very thin, sharp-edged and vertical cuts are obtained. When the direction of the cut is the opposite of the one of the polarisation, the energy absorption of the material is reduced, resulting in a reduction in the speed of machining and a wider cut with rough, irregular edges.

Material characteristics

When configuring a laser system, the characteristics of the material must be taken into account. Not all materials are laserable. Some do not absorb certain wavelengths; others produce unsatisfactory results when subjected to the laser beam.

Thermal properties and reflectivity are the parameters of a material that need to be taken into account.

Thermal properties

From the point of view of laser processability, materials can be divided into two categories, metals and non-metals. The two groups respond differently to laser radiation and therefore offer different degrees of processability.

Metals have high thermal conductivity, a higher melting point and high optical reflectivity. For this reason, laser processing is very inefficient in most cases.

Non-metals, on the other hand, absorb laser radiation very well, particularly that of the CO2 laser, and can therefore be processed very efficiently. All it takes is a small concentration of laser energy to initiate the material transformations that carry out the processing.

Reflectivity

This property is especially relevant for metals. While we can generally say that all metals have a high degree of reflectivity, it is not a fixed parameter. The reflectivity of a metal can vary as the physical properties of the metal change. For example, reflectivity decreases when a metal is heated or when shorter wavelengths are used.

The reflectivity of a metal can be limited by the use of a non-reflective film applied to the surface of the material.

The polarisation of the beam also affects the reflectivity of a material.

Process characteristics

The laser machining process can be carried out in many different ways and use different technologies.

The following features of the machining process influence the final result:

• beam travel speed
• assist gas
• nozzle shape
• stand-off distance
• focal plane position and focal length

Beam travel speed

The travel speed of the beam is crucial in determining the final processing result. The thicker the material, the slower the laser has to travel because if it is too fast, it cannot penetrate the material.

In some cases this principle can be used for a purpose, such as laser marking and engraving.

On the other hand, if the laser proceeds too slowly, the material gets too hot, increasing the heat in the affected zone, which can lead to charring and damage to the material.

The right speed is the one that achieves the best quality for the desired result, as efficiently as possible.

Gas assist

In some cutting processes, the laser emission may be accompanied by a gas jet. This technique makes it possible to improve the efficiency, speed or quality of machining.

Some of the most commonly used gases are oxygen, used to cut mild steel, nitrogen, to cut nickel alloys. Helium, argon and other inert gases and simple compressed air are also used.

The gas jet can be either coaxial to the laser beam or directed. The final decision depends on the characteristics of the desired processing.

Nozzle shape

The nozzle is the device through which the laser beam is irradiated onto the processed surface. Its configuration has an influence in determining cutting characteristics such as shape, size and edges.

Stand-off distance

This parameter is determined by the distance between the nozzle and the processed surface. The spray distance affects the gas flow. Too great a distance can cause turbulence, which creates irregularities in the cut. If, on the other hand, the nozzle is too close to the work surface, splashes of molten material can damage the laser’s focusing lens.

Focal plane e position and focal length

The laser needs to be focused on the working surface at all times. The focus point must therefore always be on the processed surface, in order to achieve maximum energy density and precision. Controlling this parameter is essential to obtain good quality and uniform processing along the entire path of the laser.

Every laser configuration is specific

In summary, it is clear that it is not possible to standardise laser applications. The processed materials, the characteristics of the process and the technical characteristics of the laser system determine the type of configuration one should use. Contact us: our experts can define a process that suits your needs!

Over the years, different types of lasers have established themselves thanks to their versatility. Apart from technical differences in construction, the particularity of each laser lies in the propagation medium used to emit energy and the resulting wavelength.

The most common are gas lasers (such as the CO2 laser), semiconductor lasers, fibre optic lasers and solid-state lasers. Depending on the medium used, the laser generates a beam at a different wavelength. The lasers manufactured so far cover the entire electromagnetic spectrum.

Why the laser wavelength is key

The wavelength is crucial in determining the possible uses of a laser. From it depends the kind of interactions between the laser and the material. Each material responds differently to a certain wavelength. Some materials, like acrylic, can absorb in the near IR or be transparent in the far IR. The optimum balance is achieved when most of the energy generated by the laser is absorbed by the material, allowing efficient processing.

Based on what we have said, it is impossible to establish an optimal wavelength. The choice depends on the characteristics of the material to be processed.

However, it is possible to give general indications. It has been demonstrated that some lasers have a wavelength which makes them suitable for a wide range of applications.

The wavelength of CO2 laser

The CO2 laser in particular has a wavelength of 10.6 micrometres, which is in the far-infrared region. This length is absorbed very well by all materials containing carbon. Wood, paper, plastic polymers, organic materials, natural and synthetic fabrics respond perfectly to CO2 laser radiation.

What’s your need?

Certainly, of all lasers, the carbon dioxide laser has proved to have the greatest versatility and has therefore established itself as the main choice for the laser processing of materials. Contact us for more information!

The CO2 laser has been on the market for many decades. Over the years it has proven to be a sturdy tool, capable of providing thousands of hours of processing without having to be serviced or replaced.

Unlike for mechanical production equipment, one of the biggest advantages of laser processing is low maintenance.

Mechanical tools operate by contact between parts and rely on moving mechanisms. The friction generated during machine operation makes wear and tear on this production equipment a pressing problem. Periodically, production has to be stopped in order to carry out the necessary maintenance operations, which increases the costs of operation and processing. The die sector is but one example of an industrial process that suffers from this problem. In this type of application, the dies have to be replaced periodically to guarantee the quality of the cut.

Laser, on the other hand, is a non-contact process. The entire laser system is based on the production and transmission of electronic pulses and the generation of polarised light beams. There are no moving parts or friction and therefore no direct impact on the lifetime of the laser source.

However, this does not mean that laser sources are maintenance-free. Laser sources also wear out, albeit much more slowly. This is why they need regular maintenance.

In the case of CO2 laser sources, the main problem is the rarefaction of the gas inside the laser tube. Year after year, the gas mixture is normally depleted, resulting in around a 1-2% emitted power decrease per year. This causes a gradual deterioration of the processing and a consequent decrease in efficiency.

The only solution to this problem is to periodically regenerate the laser source. However, this is a costly and time-consuming operation that usually involves stopping the production line, resulting in a negative impact on productivity.

El.En. has created a series of laser sources based on Self-Refilling technology to overcome this very problem. These sources, called Never Ending Power, avoid the regeneration of the source thanks to the use of a cylinder that contains the propagation medium. This cylinder can easily be replaced without causing any delays and guarantees the same process parameters and power over time.

This innovative recharging technology now makes it possible to have a laser source that always functions at maximum power. The laser beam’s quality will consistently remain at its highest level and the lifespan of the laser source will practically be infinite. Contact us for more information!

Laser cleaning is the process of using lasers to remove dirt, debris or contaminants from the surface of an object. It is a process that lends itself to a variety of industrial and non-industrial applications. From cleaning thermoforming moulds to restoring monuments, there is no area where laser cleaning cannot be successfully applied.

In this article, we explain what the laser cleaning process consists of, the principle on which it is based and why it has an advantage over conventional cleaning methods.

Conventional cleaning methods

In the field of industrial production, the maintenance of production tools is essential, particularly in those areas where the quality of production depends on it. In the plastic thermoforming sector, for example, it is essential to always have clean moulds in order to obtain high quality parts. Rust, dust and material residues are among the most common types of dirt that need to be periodically removed.

However, cleaning operations are very costly in terms of resources. The actual performance depends on the type of maintenance required. But in general we can say that cleaning methods are based on the use of chemical or mechanical methods.

In the first case, cleaning is entrusted to solvents, detergents or other chemical compounds that degrade the material to be removed and facilitate its removal. In the second case, systems such as sandblasting or ultrasonic cleaning are used.

These cleaning methods have major disadvantages. They are very polluting because of their use of chemical products and require operators to take special safety precautions.

In addition, physical contact often causes damage to the workpiece which, in the long run, ends up being damaged by the cleaning operations.

Laser cleaning has established itself precisely because it has the advantage of overcoming the main drawbacks of traditional cleaning methods.

Laser cleaning and its advantages

Laser cleaning consists of irradiating the surface of a material in such a way as to remove the surface layer. The technique is based on ablation. The beam concentrated on the material breaks the molecular bonds of the material that needs to be removed. The material evaporates instantaneously with virtually no residue left behind.

Unlike conventional methods, there are no solvents or other additional chemical substances used in laser cleaning, and since it is a non-contact process, there is no abrasion that could damage the workpiece, as the surface dirt is removed without attacking the underlying material.

It is precisely this protection of the material that makes the laser so attractive. The laser allows you to operate selectively on a given material. The laser only removes materials that are absorbed by its wavelength. In addition, each material has different properties and needs a different amount of energy to be removed. This makes it possible to work on materials very precisely, to calibrate the laser extremely selectively so as not to damage the underlying material.

Flexibility, high controllability of the medium and speed are the characteristics that make laser cleaning an extremely effective tool.

Laser cleaning is one of laser’s many applications. The process is based on laser ablation, i.e. the removal of a portion of material from a surface. Ablation is at the basis of all common laser processes: cutting, drilling, engraving, marking.

While the purpose of these processes is to create cuts, holes or marks in the material, the aim of laser cleaning is to remove dirt particles from a given surface.

Laser cleaning of industrial moulds

The production process of thermoplastics is an example of an industrial laser cleaning application. The main production method for these materials is moulding. At the end of the production process, the moulds need to be restored to their original state. This step is crucial because the quality of the final part depends on it. The presence of material residues, or other debris, affects the final quality of the parts.

Traditionally, the cleaning process is carried out using one of three techniques: dry ice blasting, ultrasonic cleaning or manual cleaning. Each has both advantages and disadvantages.

Dry ice cleaning consists of directing a high pressure jet of dry ice onto the mould. The ice penetrates the mould cavities and removes residues. The operation is carried out by an operator who directs the jet onto the areas that need to be cleaned. The advantage of this technique is that it can be used directly in the production line. However, it is not an environmentally friendly method since it requires the use of large quantities of dry ice.

For ultrasonic cleaning, the mould is placed in special ultrasonic cleaning machines. In practice, this involves disassembling the part and immersing it in special tanks filled with solvent and water. In addition to the need to disassemble the mould, this method has the disadvantage of using polluting chemicals.

Manual cleaning consists of cleaning the moulds using a solvent and manual force. It is a slow and inefficient method.

Laser cleaning overcomes these disadvantages.

Firstly, it can be performed selectively: the laser only acts on materials that are compatible with its wavelength. Laser cleaning can therefore be used in sensitive applications where abrasion-based procedures such as sandblasting would be too invasive.

The absence of waste also makes it an environmentally friendly technique. Laser cleaning doesn’t use solvents or other chemicals, doesn’t produce any waste and also doesn’t consume water or other resources. It is a thermodynamically efficient process. The laser vaporises the material by sublimation which makes it an environmentally friendly process.

Finally, laser cleaning is extremely precise. The process is completely digitally controlled which makes it possible to work on extremely small surfaces or follow extremely complex cleaning patterns. Unlike with traditional methods, it can clean hard-to-reach spaces and uneven surfaces.

A system tailored to your application

Laser cleaning is a versatile application. It is efficient, adaptable, precise and most importantly, ecological. El.En. is the ideal partner to create a tailor-made application for your production process. Contact us and we will be happy to help you find the best solution for your needs!

The manufacturing process of abrasive materials has always been a productive challenge. The main problem is that the abrasive power of these materials also exerts itself on the production tools themselves, damaging them over a short period of time.

This results in very high maintenance costs for the tools. In addition, the fact that using precision tools is difficult makes it impossible to carry out precise machining on these materials.

The introduction of laser technology was therefore a major innovation, as it made it easier and cheaper to manufacture abrasive tools and materials:

• Laser production processes are contactless. In laser processing, no mechanical forces are involved, unlike in traditional manufacturing processes. The interaction between the laser beam and the material produces a high energy density that removes a certain amount of material.
• Laser technology enables a high degree of control over the production process. What does that mean? It is possible to set up the laser parameters, down to the smallest detail, in order to minimise the difference between the desired result and the result obtained. In other words, you can create a material with characteristics that are perfectly suited to its intended use.

Diamond abrasives

A few decades ago, diamond abrasives joined the ranks of traditional abrasives. These tools exploit diamond’s exceptional hardness and thermal conductivity to achieve excellent abrasive performance.

Diamond is one of the hardest materials known to man. It also has excellent strength, good wear resistance and a low friction coefficient.

Diamond tools can be used in a wide range of applications:

• geological prospecting
• stone processing
• construction
• woodworking
• tooling
• ceramic processing

Diamond tools can be manufactured in various ways. Generally, synthetic diamonds are used, or diamonds judged to be of unsuitable quality for jewellery making.

To make tools, diamonds are combined with another bonding material so that, for example, tools can be made from metal, resin, ceramics, etc.

They can also be used for a wide range of purposes, including all traditional mechanical operations. These include cutting, drilling and, among other things, abrasive tools.

The manufacturing process for diamond abrasive tools comes with the same difficulties encountered in the production of conventional abrasive tools. However, it also has an added difficulty: the hardness of the diamond subjects the production equipment to even greater stress.

Here too, the CO₂ laser can be an advantageous solution.

Diamond abrasives can be subjected to laser ablation processes using a continuous wave laser. This technique can create textures and other passive layer characteristics that enhance the performance of the material.

The process is especially effective on resin bonded abrasive materials. Resins and plastics in general absorb CO₂ laser radiation very well and, therefore work very effectively for laser ablation processes.

A new application for the CO₂ laser

Diamond is one of the hardest materials in existence, which makes the efficient production of these tools difficult and limits their widespread use. On the other hand, however, diamond abrasive tools offer enormous advantages and are crucial in certain applications. The introduction of laser machining processes has made their production more efficient and cost-effective, paving the way for their widespread use. Research in the field is still ongoing, bringing with it other possible applications in the future.

El.En. has been producing CO₂ lasers for various industrial sectors for over 35 years. Experimentation, research and development in the field of lasers applied to materials is in our DNA. If you are thinking of making an application of this type, contact us and we will be happy to study the ideal solution for your needs.

Composite materials are known for their extraordinary mechanical and physical properties. They are created by combining two different materials, resulting in a new material with better properties than their component materials taken individually.

Fiber reinforced polymers are some of the materials in the composite family that have found widespread use. These materials are manufactured by incorporating a fibre of some kind into a resin polymer matrix.

Fiberglass is one of the first materials to have been made in this way. Invented in the 1960s, it has now become an indispensable material for many sectors, particularly the nautical one. Today, there are other materials of this type such as aramid fibre also known as kevlar and carbon fibre reinforced plastics (CFRP).

Materials produced this way are light and resistant and at equal mass, are considerably more performant than other traditional materials such as wood or metal. They can also offer great plasticity which makes them easy to mould into any required shape. Thanks to these characteristics, composite materials are used for technologically advanced applications in sectors such as the nautical, aeronautical or automotive industries.

Carbon fibre reinforced plastics

CFRPs are perhaps the most advanced of all the composite materials,

To produce CFRP, a carbon fibre fabric is incorporated into a polymer matrix. The resulting product is extremely light and strong. At equal mass, it is 25% lighter than aluminium and 60% lighter than steel. This explains why it has found use in the aeronautical industry and in the sports competition sector for the construction of super light vehicles.

Once made, however, CFRP must be cut into the required shapes for their future function. Normally, this is done using mechanical methods. However, these have a major drawback. The strength of the carbon fibre quickly wears out the cutting tools, which therefore have to be replaced very frequently, making the process very costly.

Laser cutting technology is a valid alternative to the mechanical cutting of CFRPs. Both the carbon fibre and the polymers that make up its matrix absorb the 10.6 micrometre laser radiation produced by the carbon dioxide laser very well and can be cut very efficiently.

Cutting CFRP therefore has two main advantages:

• a contactless process: it is possible to cut CFRP without the typical mechanical forces that wear out the cutting tool. This significantly lowers the production costs of each individual part.
• very high tolerances: the laser can make cuts with very narrow angles and produce extremely precise parts very easily. This feature is crucial for advanced technological sectors where it is important to maximise the performance of a given component.

The material of the future

CFRP will become more and more popular over time. This material is of increasing importance and will spread to an ever wider range of sectors.

Finding a cheap and fast way to cut it into the most diverse shapes will become crucial. The CO₂ laser is a viable alternative to the mechanical cutting methods currently used.

If you are considering a laser application to process carbon fibre, contact us: and we will design a customised application to suit your needs.

Laser marking is one of the most widely used laser processes in the industrial sector. It is typically used to apply information to packaging: expiry dates, traceability codes, production batches, logos and other graphics. The fundamental advantages of laser marking over traditional methods are the very high processing speeds and the high levels of precision that can be achieved.

But the advantages don’t stop there. Laser technology not only allows manufacturers to increase processing efficiency parameters, but also to perform types of processing that would be impossible to do with traditional methods.

How does laser marking work?

Laser marking is a processing technique in which a laser is used to produce an engraving on the surface of a product. As with all laser-based processes, this technique exploits the laser’s ability to concentrate large amounts of energy on one spot with a diameter of a tenth of a millimetre. At the site where the laser touches the material, very high energy densities are reached, which cause the temperature to rise within a few seconds, triggering physical and chemical transformations.

A key feature of laser processing is the high degree of control. It is possible to decide with great precision how deep the laser’s action should go. With laser marking, the mark is only produced superficially, on a layer that goes from a few microns to one or two millimetres. Past this depth, one no longer speaks of laser marking but of laser engraving. The two processes, although similar, differ in the depth of the laser marking which in turn changes its perception. Laser engraving creates marks that are more visible and perceptible to the touch. In laser engraving, the mark is visible but not very perceptible to the touch.

Laser marking and packaging

In all laser processing, the type of power used depends on two factors: the material one wants to process and the speed one wants to reach. As you may already know, every laser emits a beam of polarised light at a defined wavelength. Some materials absorb certain wavelengths well but not others. In the packaging sector, the CO2 laser is the one that gives the best results. Its 10.6 micrometer wavelength belongs to the far infrared region which is very well absorbed by the organic materials most frequently used for packaging (e.i: paper, cardboard, thermoplastic polymers, glass).

Advantages of laser marking

Traditionally, the following methods are used to mark information on packaging:

1. inkjet printing
2. thermal transfer printing
3. stamping
4. hot stamping
5. mechanical engraving

These techniques are always based on contact between the tool and the workpiece. Compared to them, the laser has several advantages:

1. reduced cost: the information is engraved directly on the product, which eliminates the need for any other material, such as ink and labels
2. indelibility: it is resistant to wear, solvents, scratches, light and counterfeiting attempts.
3. automation: the process is fully automatable.
4. flexibility: laser marking can imprint any type of information, however complex.
5. contact-free: materials are not subjected to mechanical stress.

Materials and laser marking

As mentioned above, the characteristics of the material used influence the specific characteristics of the marking operation.

Paper and cardboard packaging

Paper and cardboard are made from cellulose, a material of organic origin produced through wood processing. The laser acts on the paper by vaporising a thin layer of material. The resulting mark has the same light colour as the material and may therefore offer little contrast. The contrast can be increased by adding a dark-coloured overlay. In this case the laser only removes the coloured surface layer to reveal the light part underneath. The contrast between the white of the paper and the darker colour of the surrounding layer creates a very legible mark.

Laser marking on plastics

Plastic is a synthetic organic product based on carbon-based polymers. On certain types of plastic, the CO2 laser is very efficient and gives optimum results. The plastics that are best suited for laser marking are those most commonly used in the packaging industry, such as polyethylene, PET or polypropylene. Polypropylene is also suitable for laser cutting.

Laser marking on plastics is carried out by chemical transformation (the laser breaks polymer chains). The fact that the light affects the mark differently to the surrounding material makes it quite visible. Depending on the additives applied to the plastic, different levels of contrast can be achieved.

Laser marking on glass

Laser marking can also work with glass. Marking on glass is carried out through the physical transformation of the material. Glass is a very fragile and inflexible material that traps micro-bubbles of air inside itself. When the laser strikes the surface of the material, the air bubbles expand due to the heat, creating micro-fractures. This changes the transparency of the material and creates the mark.

Beyond packaging

In some cases, laser marking can eliminate packaging. In recent years, laser marking on food has become a well-established technique. It is mainly used on produce or cured meat and cheese but can be used on any compatible product. In this application, the marking is done directly on the surface of the product. A layer, a few microns deep, is removed from the surface. The laser beam does not penetrate into the product so its freshness is preserved. Several studies have shown that laser marking does not affect the quality of the product in any way. Food distributors rely on it to save on tons of packaging materials each year, including self-adhesive labels.

Equipment for laser marking in packaging

The technical requirements for a laser marking system are a CO2 laser source, which produces the beam, a scanning head, which moves the beam over a surface, and a software controller, which coordinates the system.

The laser source

In the El.En. catalogue we have laser sources that range from 60W to 1200W of power. Greater power corresponds to greater energy per unit area, which can be translated into greater execution speed. Our catalogue has a selection of laser sources optimised for certain packaging materials. BLADE RF177G and BLADE RF333P with their two different wavelengths of 9.3 um and 10.2 um are perfect for the materials used in the packaging industry and in kiss cutting for adhesive labels.

Our Never Ending Power sources use Self-Refilling technology that potentially makes the laser’s life endless. This involves the addition of a consumable, the gas cartridge, which contains the propagation medium and can be easily replaced when it runs out. In this way, sources can maintain their performance over time. Unlike sealed lasers, this eliminates the time-consuming and costly refurbishment process.

The scanning head

Applications such as marking are called galvo laser scanning because they use galvanometric mirrors to move the laser beam across the surface.

The main feature of our scanning heads is that they have a z-dynamic motor, which allows the focus to be adjusted in height and thus maintain constant parameters on the work area.

The digital controller

The CO2 laser source and the scanning head need software to coordinate their movements in order to perform the required machining. Our heads also include this control system, which can be easily integrated with common operating systems.

Contact El.En.

Laser marking is one of our areas of expertise. Our engineers have worked on dozens of laser marking application projects in this field. If you work in packaging and are interested in a laser solution, contact us and we will be happy to find the best solution for your needs.

Bags and pouches of all kinds have been conquering the packaging market for several decades now. Flexible packaging adapts to the shape of the object it covers, so less material gets wasted. Laser perforation, also known as laser drilling, is a processing technique that allows the manufacturing of new packaging designs that at the same attract the eye and have advanced functional features. Laser perforation is but one of the many processing technique that can be employed in packaging manufacturing through laser.

In general, the great success of flexible packaging is due to its functional characteristics. The main functions of packaging are to first protect and preserve products, and second, to facilitate sales. Flexible packaging perfectly fulfills both functions in a terrific way. Not only does it protect the product from external influences, but it can also be easily processed to give it the shape that best enhances the product’s characteristics.

Here are some examples of the wide variety of shapes and configurations flexible packaging can have:

• stand-up doypack pouches
• heat-sealed plastic bags
• envelopes for product samples used for promotional purposes
• pre-printed plastic film reels

Packaging of this type is employed in various industrial sectors. The food industry is one of the ones that makes the most common use of it. Flexible packaging provides the delicate products of this industry with an optimal balance between weight, protection, hygiene and functional and commercial characteristics. Other sectors such as cosmetics, health care and detergent industries also make extensive use of them.

The materials used to produce these forms of packaging fall into into 3 basic families:

• plastic film – Polyethylene and polypropylene are the main thermoplastic polymers used, they provide high insulation properties
• aluminium foil – Aluminium foil is used when high protection against light or temperature changes is required
• polycarbonate – These are created by combining materials from the previous two families to combine the advantages of both materials

Laser perforation for flexible packaging

As we have already mentioned, flexible packaging has found widespread use in the food sector in particular. As more and more people live in cities, work and have little time to cook, the demand for fresh, ready-to-cook food has increased.

This type of packaging is used the most for products such as vegetables. In the fresh produce section of supermarkets, bagged vegetables have become the norm, and a convenient solution for people who want to eat vegetables but have no time to prepare them.

The challenge for producers here is not only to adopt sustainable packaging but also to maximise the shelf life of their products.

After being harvested, fresh food goes through a series of biological transformations that manifest themselves in the release of gases, water vapour and chemicals inside the bag. As a result, unsuitable conditions for product preservation are created inside the bag.

What is laser perforation?

Laser perforation makes it possible to overcome this problem. The creation of holes in the surface of the wrapper makes it possible to optimise the gas exchange between the inside and the outside environment. It then becomes easy to maintain the optimum conditions for better product preservation.

This technique is part of laser cutting processes. In this application, laser technology is used to create holes in the material. The most remarkable aspect of this process is that it makes it possible to define the characteristics of the holes very precisely, from their diameter to their shape. This gives this process a considerable advantage over conventional packaging methods. Whereas previously a manufacturer had to find the most suitable packaging already available on the market, with laser perforation they can customise the packaging to ensure optimum product preservation.

The advantages of laser perforation

Compared to traditional perforating methods for flexible packaging, laser perforation provides a number of advantages:

• Precision: like all digital processes, laser perforation offers all the precision given by the use of software. The size of the holes can therefore be changed according to a wide range of parameters, even during the same process.
• Protection of materials: laser technology minimises the possibility of accidentally damaging the material from which the plastic film is made.
• Automation possibilities: laser perforation is a fully automatable process. It can be incorporated into existing production processes in order to fully automate and increase the manufacturing quality of the whole production line. It can be used for roll-to-roll or sheet-to-sheet processing.
• Flexibility: different processes, within the same production cycle, can be performed with laser technology. The same machine can perform more than one process, like for example, perforating plastic film and marking information for product traceability.

What materials can laser perforation be performed on?

The best results in laser perforation are obtained with plastic film. Most thermoplastic polymers absorb the radiation of the CO₂ laser well and therefore lend themselves perfectly to this type of processing. As we have seen, polyethylene and polypropylene are the materials on which the best results are obtained. On these materials, the cutting edges are perfectly defined, the processing precise and clean.

How a laser perforation system works

Choosing the right laser perforation system amongst the wide range of options on the market depends on the material used, the type of application and the final purpose of the project. However, we can identify some constants in all systems.

A laser perforation system normally consists of 2 components:

• a CO₂ laser source: this is the device that produces the laser beam. You can find laser sources with different power options in the El.En. catalogue.
• a scanning head or focusing head: the laser scanning head is the device that moves the laser beam over a surface. In this way, perforations can be distributed over the surface according to production needs. This smart tool uses integrated control software and can follow any type of pattern. For simpler machining operations, this system can be replaced by a focusing head, which does not have a control system but allows the laser beam to be focused on a specific point that can be moved on one or two axes depending on requirements.

This combination of basic elements can be integrated into an infinite range of systems, from industrial in-line systems to stand-alone machines that do the processing independently. Laser systems can act on moving material from reel to reel or on sheets of material.

Contact us

The possibilities of laser perforation are endless. This article only covers one of the many possible applications. This technique can be used to create filters, disposable packaging, and packaging with particular and perfectly defined functional characteristics. Each application has its own peculiarities. Our job is to find the laser solution that gives you the best results for your application. If you think laser perforation might be right for you, send us a message and we will be happy to help you identify the best laser solution for your needs.