A laser beam source is at the core of every cutting system. The beam is guided from the source by a system of mirrors or a fibre-optic cable to the cutting head at the entry point to the cutting table. The CNC tables designed for cutting in 2D that are used today essentially come in two types – with hybrid optics (the clamped material moves on one axis and the cutting head on the other) and with flying optics (the cutting head moves on both axes). In the cutting head, the beam is concentrated on to a technologically precisely defined focus, depending on the type and thickness of the material. The laser beam’s concentrated energy melts the material that is to be cut and the kerf is continuously “blown” with an inert assist gas, most commonly nitrogen. This is known as “fusion cutting” (and results in clean, non-oxidised, polished cuts). Alternatively, it is melted and burned off – with oxygen as an assist gas – in a process known as “oxidation cutting” (resulting in cuts with a noticeable trace of oxidation). Finally, it can be melted and evaporated by means of the less common ”sublimation cutting”. The upper technological limit for high-quality laser cutting in everyday industrial practice today is material that is 25-30 mm thick. This limit is increasing all the time as advances are made.

Besides metals, lasers can generally cut certain plastics, wooden materials, etc., if they have been specially finished. However, as it is better to cut most of these materials with a water jet (partly in order to avoid noxious fumes), our centre specialises in metal cutting: structural steel up to approx. 25-28 mm thick (or up to 30 mm if special sheet metal is used that has been optimally modified for laser cutting, e.g. Raex, SAEY-LaserFORM, Domex, etc.), stainless steel up to 20 mm thick (or up to 25 mm if simpler shapes are cut), aluminium and Al alloys up to 18 mm thick (at larger thicknesses burrs are formed, so it is better to use water cutting), brass, bronze, copper and other metals up to approx. 3-5 mm thick, perforated sheet metal, etc. It is best to use sheet metal specially prepared by the manufacturer for laser cutting because, although the price of the material is higher, the cutting is faster and cheaper and the cutting quality is better. The surface of some sheet metal needs to be ground, oiled or otherwise treated prior to cutting. For metal sheet of unclear composition or origin, we recommend performing cutting tests before the actual cutting.

Sheet metal coated with a protective film can be successfully cut if the film is used only on one side and is specifically designed for laser cutting (most manufacturers routinely offer this solution). While the edge of the film is slightly singed, no marks are left on the product. In cases of doubt, it is better to conduct a cutting test on the specific material.

A laser cannot cut multiple sheets on top of each other, even at low thicknesses. The parts would become welded together and other complications would arise during the cutting process.

General speaking, any shape that can be transferred to CAD drawing software. During cutting, the laser-focused beam has a circular cross-section with a diameter of 0.1 to 0.5 mm. This means that the inner corners and inner sharp angles are rounded, but usually only by a negligible radius of no more than 0.3 mm. The outer corners can be completely sharp. The width of the kerf also ranges up to a value of approx. 0.5 mm. All other shape-related limitations can be attributed to the amount of heat transferred to the material during cutting, and, as such, to the degree to which the material melts and is subsequently deformed. As a general rule, the thinner the sheet metal, the faster the cutting, which means less heat and fewer shape constraints.

Holes can be cut into black sheet metal with a minimum diameter equal to approx. 0.8 to one times the thickness of the material (e.g. D 8 up to a thickness of 10, D 15 up to a thickness of 15, etc.). With stainless steel, even holes that are smaller than approx. 0.5 times the thickness can be cut. This rule can also be applied to differently shaped holes. In special cases, smaller holes can be test-cut, depending on the material, the density of the holes, etc. The larger the share of cuts and metal loss per unit of area (dense networks of holes, very complexly shaped cuts, etc.), the greater the risk of shape deformations in the material – bends, twisting, etc. This factor is again linked to the thickness of the material – the thicker the material, the greater the risks. In extreme cases, cutting may be infeasible – the material melts due to the high degree of heating, the cuts weld back together, etc. As the thickness of the material increases, the possibility of using combined cutting also decreases. In fact, the distance between the parts needs to be increased, which reduces the percentage of material utilisation somewhat.

Our machines cannot do bevel and 3D cuts. The cut must always go through the entire thickness of the material. Our machines can be used to mark and describe parts by means of laser engraving. As the machines are not designed specifically for this purpose, this laser engraving is a relatively slow process and is priced at more or less the same level as normal cutting.

The final result of cutting always depends on all the effects described above, the material used, the correct programming, and on how the cutting specifications are configured. Since virtually anything can be tested, we recommend running cutting tests if there are any doubts.

Of all heat-related methods for cutting materials, laser cutting results in the lowest amount of bevelling. Again, the thickness of the material is a factor: on thinner sheet metal, the cut is almost perpendicular, whereas if thickness is around 10 mm, there may be bevelling of up to about one degree.

The program for processing the cutting codes functions as an extension to the CAD module. Therefore, the shapes that are to be entered must always be converted to CAD format. The ideal file type for this purpose is *.dxf. We can also handle STEP models. The programming station is also equipped with CorelDRAW 9, so it is possible to process files supplied in *.cdr format (for these files it is advisable to include a proportional scale in the drawing or to provide at least some dimensioning as the scale may be distorted during conversion to CAD). Naturally, classic engineering drawings or diagrams that have been properly dimensioned can also be effortlessly processed. If only a sample of the product is supplied, it should be borne in mind that ordinary measuring methods (a slide rule, a tape measure, a workshop protractor, etc.) are used for redrawing and may result in minor deviations. When signs, advertising components, etc., are commissioned, we can provide assistance by using our own databases and creative ingenuity, backed by our knowledge of what the technology is capable of.

With laser cutting, the quality of the cut cannot be changed at the various stages by altering the cutting parameters. It is always necessary to configure the optimal cutting parameters, and thereby achieve optimal cutting quality. Again, this depends on the thickness of the material. Generally speaking, up to a thickness of approx. 5-8 mm the cut is smooth, straight, and free of scale. As the thickness increases, the grooving typical of laser cutting appears, and minor scaling and weld-ons may form on the underside. At the upper thickness limit, the grooving is quite pronounced and the negative elements on the underside may also be more substantial (again, this depends on the amount of heat introduced). We are able to clean the parts if required. Courtesy of our new deburring grinder and the high quality of the cut delivered by modern laser machines, besides standard laser-cut parts we can supply parts perfectly deburred or cleaned in line with the customer’s specific requirements. + FOTO

With stainless steel, nitrogen (achieving a polished high-quality cut) may be replaced by oxygen as the assist gas. This reduces the price quite significantly (by about 20%). On the other hand, the quality of the cut is much worse (the cut is black, oxidised, and rough).

The cutting price depends on the type and thickness of the material, the complexity of the cut’s shape, the amount of metal loss and number of holes, the scale of serial production required by the order, the overall volume of orders stemming from long-term cooperation, the demands of handling, the cleaning and packaging requirements, etc. As so many variables have to be factored into the pricing, it is impossible to set any objective listed or indicative prices per metre of cutting, etc. When you make an enquiry, we will prepare an exact quotation for you very quickly.