Laser Cutting of Polymers
Polymers can easily cut and weld with laser beam. Laser cutting of different polymeric materials (polyethylene PE, polypropylene PP and polycarbonate PC) is mainly carried out by a CO2 laser and Nd:YAG laser. All polymers can be cut by means of a combination of three processes: fusion, vaporization and chemical degradation. It is possible to classify plastic materials according to which of these three processes prevails when they are cut.
Laser Cutting of Paper materials
It is known that CO2 laser beam is suitable for cutting of paper materials. The combination of laser an paper has been studied over 30 years, but still implementation of laser technology in the paper industry has remained limited. This situation changed in 1990´s: laser equipments were cheaper, improved lasers were developed and the laser technology became more reliable.
Cutting mechanism in laser cutting of paper materials is vaporisation cutting. This mechanism means a cutting method where laser beam heats up the material top surface to evaporation temperature or to temperature where chemical degradation happens. Usually inert cutting gas (like nitrogen) is used to prevent combustion of vaporised material.
Paper/board making and converting industry needs high-capacity machines. Conventionally cutting of fibre material is done by mechanical blades or die-cutting. In 80´s water jet became as a competitive cutting method. In laser cutting studies of paper materials carried out in Lappeenranta Laser Processing Centre (LPC) it has been found that a magazine paper can be cut with laser beam at speed of 4400 m/min. This speed totally fulfils the requirements of papermaking process.
Generally it can be said that laser cutting in cutting of paper materials is recommended in following circumstances:
- wherever production size is small or constantly below 1000 pieces.
- always with digital printing.
- when high accuracy with complex geometries is needed.
- when flexible production and fast delivery is needed.
- when tailor-made products are needed.
When paper/board is cut with conventional mechanical blades there are several problems, which make the cutting quality bad or even destroy it. A big problem in mechanical cutting of fibre material is dust which consists of piece of fibres and pigment particles ripped out of paper by cutting blades. This dust causes for example runnability problems in printing houses. Also in many cases coarse cut edge which contains out-sticking fibre endings causes many problems. For example in liquid packaging industry such a problem is not wanted because liquid absorption properties of cut edge are very important.
Laser cut rocking chair