The new generation of engraving laser filters
means that packaging firms can expect better performances, claims
Purex marketing manager Jon Young. But in all cases, some form of
fume extraction system is still required.
Marking lasers are used in a huge variety of applications to add traceable information such as use by dates and batch codes to packaging and products. Engraving lasers are commonly used to mark logos and information, and can also be used to cut shapes in a variety of materials.
Both laser marking and laser engraving systems burn away layers of material to cut or mark a material. This process generates a fume that contains small toxic particles and gases that are hazardous to health. Some examples are benzene and toluene released from certain plastics and chromium and nickel given off by some metals.
The particulate generated by laser processing can also coat or even damage expensive laser optics and cause beam attenuation leading to blurred or incomplete marks. If this dust is not removed efficiently it can also contaminate products that may need to be rejected and it can coat the laser enclosure and associated machinery meaning increased downtime for cleaning.
"A failure in fume extraction is usually a 'line stopper,'" said Purex marketing manager Jon Young. "In high volume production (e.g. PCBs, pharmaceuticals, food/beverage packaging) improperly coded products and the resulting downtime due to fume extraction failure can cost thousands."
Young claims that it is now widely accepted that some form of fume extractor is required when purchasing a laser. "The laser sales person may think that quoting a laser with an extractor will put the customer off because of the additional cost, but this is usually not the case as the customer knows they will have to buy an extractor from somewhere anyway," he said.
New lasers coming onto the market are less expensive and more compact, so a good extractor needs to be compact, affordable, quiet, mobile and deliver excellent extraction rates and filter life. Young claims that the new Laserex Alpha from fume extraction specialist Purex has been designed along these key principles.
"The basic machine offers the customer a very affordable solution and comes in two models, a 200m3/hr and a 400m3/hr version depending on the size of the laser," he said. "Both models have a small footprint of only 465mm2 so they take up minimal space in areas where this is a consideration. All units are mounted on lockable castors to make the machines highly mobile so if the laser moves the user can simply push the extractor after it."
To reduce noise levels the machines employ Whisper Stream technology, a unique powerful blower and silencing system that delivers good performance, maximum reliability and whisper quiet operation at less than 45dBA.
A major benefit of buying a laser, claims Young, is that they have few consumables when compared with other methods of marking such as inkjets. Therefore the last thing the customer wants is to have to buy lots of replacement filters for their fume extraction system.
As a result, several design features are employed in the Laserex Alpha to ensure filters have a long lifespan to keep consumable costs low.
The first of these is Reverse Airflow, a system pioneered by Purex in the electronics industry and now used in laser fume extraction. Large particles within laser fume will prematurely block a filter over time.
To prevent this the speed of the air is slowed when entering the Alpha machine and the direction is changed from horizontal to vertical forcing larger particles out of the air stream in an action similar to a centrifuge. These particles are then deposited in the base of the Labyrinth pre-filter thus prolonging its life.
"The Labyrinth pre-filter is used to protect the main HEPA filter from premature blockage," said Young. "It does this by removing minute particles from the airstream. This quick change, patented filter technology is not available from any other manufacturer and is designed to overcome inherent weaknesses in pleated paper and bag filter design."
Filters, says Young, will last longer if the speed at which the particles pass through the filter media is controlled and maintained. As a result, the Alpha includes a speed control system that allows the customer to set the airflow to the optimum level on site.
To prevent the extraction rate falling as the filter becomes blocked this upgrade pack also includes a fully automatic closed loop flow control system. This system maintains the airflow at precisely the level set by the operator by automatically adjusting the motor speed.
For added safety, the extraction is automatically started when the laser is switched on. This prevents any damage to the laser optics or any hazardous fume entering the workplace.
"Health and Safety legislation and the need to protect the product and laser optics make the need for a fume extraction system undeniable," said Young. "By producing the Laserex Alpha at the right price, Purex believes that it has catered for everyone's requirements."
