APPLICATION FOCUS: SAFETY
and other areas nearby. Correct extraction system design will help keep equipment, including hoses/ ducting and filters, clear of particulate build-up. Regularly changing filters and cleaning or replacing ductwork will also reduce fire risk and hazard. Thermite mixtures should
also be avoided. The most common of these is iron oxide and aluminium – these do not need a source of ignition, burn very hot and don’t need a supply of oxygen. Therefore, aluminium and steel must not be processed on the same laser platform without thorough cleaning and the use of dedicated filter systems. Protective coatings and
lacquers applied to the metals can also aide ignition, or prevent oxidation when the lasered particulate is generated by forming a protective coating that can make it more flammable.
Whatever the risk, good machine maintenance and hygiene is central to risk mitigation, because a foreign object lodged in front of the laser can be an ignition source. At the same time, users need to prevent ignition sources reaching areas of particulate build up – this can be as simple as the use of a spark trap, spark arrestor or inerting powders. And, of course, appropriate health and safety arrangements will require the presence of fire detection and extinguishing units. Extinguishers should be Class D – metal fire – as water extinguishers can react with aluminium or titanium to form hydrogen, which itself is flammable.
Managing inert atmospheres safely Extra care should be taken when laser processing aluminium or titanium under inert atmospheres (eg. argon or
WWW.LASERSYSTEMSEUROPE.COM | @LASERSYSTEMSMAG
“ Good machine maintenance and hygiene is central to risk mitigation … a foreign object lodged in front of the laser can be an ignition source”
nitrogen), as in the case of AM. Inert atmospheres mean that none of the metal is oxidised and therefore, once the process is finished and exposed to air, the laser fume undergoes rapid oxidation and can catch fire. The answer is a passivation process for the fume, through the controlled reintroduction of air at a rate that manages thermal reaction.
Beware explosive conditions Where there is a fire risk there can also be an explosion risk, should there be a dust cloud of the right concentration and particle size distribution.
This is manageable through a disposable filter system where a dust cloud is not generated, or proper configuration of a self- cleaning filter system. The key message for
companies investing in fibre laser systems is to engage with their technology equipment partners and fume extraction specialists, such as BOFA, as soon as possible in the planning process. The engineers of these specialists add value when working alongside manufacturers and end-user teams, and can contribute to the design and commissioning of a system that will not only safeguard the working environment, but also optimise the value of the productivity gains available through using fibre laser technology.l
Joshua Evans, MEng (Hons) IChemE, is an applications engineer at BOFA International, a manufacturer and specialist supplier of fume and dust extraction systems
SUMMER 2019 LASER SYSTEMS EUROPE 43
Guryanov Andrey/
Shutterstock.com
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48
