Problem solving

Extracting fumes and aerosols on laser marking equipment

Beer bottle labels are marked using a clean method - the laser marker.

The laser marker is a simple, cost-effective method for product marking. On printer marking systems consumables such as ink cartridges need changing at regular intervals. With laser marking systems there are no consumables so the problem does not arise. However, the laser marking process produces very fine dusts and aerosols, loose material suspended in air. Depending on the carrier material being used, these process dusts and aerosols can be a health hazard and must be extracted safely. This is one of the requirements of the standard DIN EN 12626 Laser processing machines - Safety requirements.

The Brauerei Felsenkeller brewery in Herford, Germany took this requirement very seriously but quickly discovered that the solution was anything but simple. The extraction system already supplied with the beer bottle label marker caused frequent problems. Ruwac-Industriesauger GmbH was commissioned to provide a solution to safely and reliably extract the laser marker dust at source. The solution was to extract the aerosols and also the fine, sticky dust given off by the film material. The small amounts of carbon monoxide released during the marking process also had to be dealt with.

For this application Ruwac chose a 3-stage vacuum unit with a large filter area. The extracted dust and contaminated air is drawn into the main filter and then passes into the residual dust filter for Class H dusts. This filter has a separation efficiency rating of 99.995% and thus holds back any fine dusts present. The dusts are sticky and the surfaces of the filter material have been specially treated to take this into account. The dusts held back drop down into a silo fitted with a bagger unit which can be emptied at regular intervals.

Filters, however, cannot remove the harmful gases such as carbon monoxide from the process and this job must be done by employing adsorbents. The system therefore has a two-stage, active-carbon adsorber filtration section which traps even the tiniest particles of noxious material. After passing through these two filtration steps, the contaminated air is now so clean that it can be returned to the workshop environment. Efficient extraction has also improved marking quality. There are no longer any fumes and vapours to cloud the laser lens or to dirty the label.

The Herforder Felsenkeller-Brauerei brewery initially ordered just one vacuum unit from Ruwac. Now after months of trouble-free, continuous service from the original unit they have ordered a second vacuum. The second unit is very similar to the first. The suction unit which provides the vacuum necessary for extraction is mounted separately and not on the filter unit. This layout improves access thus making filter maintenance much easier.

Ruwac vacuums are modular and are therefore easy to modify in this way. Modular construction also means that standard components can be used for a wide variety of applications. A modular Ruwac vacuum can be adapted at a later date to match new working conditions or applications without any problems.