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Machining Video: CO2 Laser Machine Cutting Leather Without Burning Mark - Shield with Nitrogen Gas
In this video you will learn about burn marks / heat marks and how to prevent them. By now you know that C02 laser cutting implies that we burning through a material and that engraving is delicately burning into it. Markings will usually occur during the process, but there is a simple was to avoid them when using the CO2 Laser Cutter.
But first, how do burn marks occur?
- On the material edge as laser cuts through
- Top surface marks from fumes and debris
- Marks on the material reverse
On the material edge as laser cuts through
This differs from material to material. On plastic for instance the edges appear melted / slightly glossy. On more combustible materials such as woods, papers and card edges look more brown / black.
Top surface marks from fumes and debris
Fumes and debris are emitted when cutting / engraving. These fumes are extracted from the rear or base of the machines. The fumes are dragged over the material surface causing marks. Marks also appear from hot debris which glazes or scorches the exhaust-facing edges of the cut line. (most noticeable on thick materials and more combustible materials.)
Marks on the material reverse
When the laser comes into contact with the cutting bed as it slices through the material, debris is deposited onto the reverse face. There are 3 types of laser beds we use depending on the job type and material. When laser cutting your material needs to be supported efficiently from underneath to allow it to remain flat at all times but also allow heat from the laser to escape from underneath. Unfortunately the more contact the reverse of the material has with the laser bed the higher the risk of marks on the reverse. The ideal scenario is for us to completely float the material so no heat builds up underneath. The ability to do this depends on your artwork and the type of material being cut. Paper for instance needs quite a lot of support as it is not a rigid material.
PREVENTING BURN MARKS
So, back to our subject headline. What does Nitrogen shield gas do? It blasts the smoke far away from the substrate, allowing the exhaust nozzle to remove the particles. In simple English, compressed Nitrogen is used to remove heat and combustible gases from the top material surface. By directing a constant stream of compressed air at the point where the laser meets the material, flaming, scorching and charring is reduced on materials such as wood, acrylic and rubber. It also helps to limit smoke deposits on the material reverse.
For all our machines and their full descriptions, please do check our website at am.co.za. You may also call our office on 060 600 6000 and speak to our dedicated sales engineers for a detailed explanation.