Efficient Extraction From a Laser Cutting Machine

Most people when evaluating which laser cutting machine to purchase perform a simple tick-box exercise listing the various functions and features as listed in the manufactures sales brochure. Few actually analyse those features in detail to see how well designed they are and even fewer test those features to see how well or efficient they work.

Inefficient laser fume extraction is very costly in terms of increased maintenance, decreased throughput, poor quality output (wasted materials) and reduced component life. Bad extraction will be hazardous to the health of the operator and is the biggest cause of flaming (fires) in Laser Cuttes.

One of the most misunderstood and overlooked aspects of a laser cutter is the efficiency of the laser fume extraction design. In the majority of plotter format machines, extraction is taken from a vent positioned at the rear of the worktable. This causes fumes to be drawn over the surface of the material.

This type of extraction is generally OK for laser engraving but not at all good for laser cutting because the rising fumes block the path of the beam, dropping laser efficiency. The direction of air can cause lightweight materials to move on the worktable and this design of extraction often allows contaminants to contact with the laser head. The platen used in almost all such machines will quickly contaminate, causing a restriction with air-flow.

Some of the larger format machines utilise extraction from the laser head by way of a long, flexi hose. Again, this only works for engraving but it has many inherent faults. Firstly, the hose contaminates fast, restricting flow and dropping efficiency and with constant flexing it will perforate over time. Because of the narrow hose diameter the vacuum pressure needs to be very high and the volume of air that can be taken in this way is very low. It’s therefore not possible to use an extract to atmosphere system with this type of local extraction. This type of extraction cannot be used when cutting small parts and/or lightweight materials as they can be pulled into the path of the beam by the air-flow.

By far the most efficient way to extract from a laser cutter is from underneath the material. We call this Underside Extraction or UE for short. This causes a vacuum underneath the material, which if the blower is strong enough can hold slightly warped materials flat to the work-table. This is especially useful for laser cutting paper, laser cutting leather or laser cutting textiles. When combined with a well designed air assisted nosecone UE will pull the laser fumes down through the cut line virtually eliminating any chance of those fumes contacting the laser head. This will often increase edge quality, especially for high debris cutting applications like laser cutting wood and reduces maintenance in some cases to near zero.

Well designed UE will provide for an even pressure and flow of air across the whole worktable so the best machines incorporate some kind of funnel underneath the worktable with the point of extraction placed centrally to the funnel.

The best laser cutting machines will incorporate dual extraction ports: one to draw over the material and another from the underside.

At Lotus Laser Systems we manufacture a wide range laser, marking and engraving solutions and can supply a wide range of extraction solutions. Our experts would be happy to advise you which configuration would suit your application best.