roughness as parameter of cut quality during c[o.sub.2] laser cutting of high alloy steel for the special purpose.
In today\'s world, new technologies are rapidly introduced into manufacturing systems for more reasons, such as: saving materials, operating accuracy, short processing time, high product accuracy, and high flexibility.
Nowadays, laser technology is widely used in manufacturing and automobile industry.
Most of the use of laser technology is laser cutting.
Laser cutting can be successfully used to cut different materials such as: metals, polymers, ceramics, composites, high alloy steel and other materials (
Avanish & Vinod, 2008).
In recent years, the application of high alloy steel in automobile body has been popularized.
The ISI institute predicts that the use of medium and high alloy steel in the automotive industry will increase significantly (Lamikiz et al. , 2005).
In the literature, there are not many experimental studies on laser cutting of high alloy steel.
The thermal reaction of iron and other alloy elements is complex, and the alloy element content of high alloy steel is high, which may lead to differences in cutting of ordinary steel.
In various types of lasers for industrial processing, C [O. sub. 2](wavelength 10. 6 um)and Nd: YAG (wavelength 1. 06 [micro]m)
Laser is the most common in the automotive industry.
In order to take advantage of the advantages of this technology, especially to save materials, it is necessary to evaluate the best process parameters, thickness and other process conditions for each material to achieve the required cutting quality with maximum productivity.
The setting of process parameters mainly depends on the material properties (
Density, specific heat, absorption rate, thermal conductivity, chemical composites, surface quality, etc)
Thickness of the material.
The most important process parameters are: laser power input, working mode (
Pulse mode and continuous wave)
, Pulse frequency, pulse duration, type and pressure of auxiliary gas, focus position, diameter and type of nozzle.
These parameters are usually determined, so they ensure the required cutting quality, while the productivity is less relevant.
The setting of process parameters that meet the desired cutting quality and high productivity is a specific problem (Rajaram et al. , 2003).
C quality [O. sub. 2]
Evaluation of laser cutting by standard process: measurement of surface roughness, deviation of cut width and cut length along cut, cut taper, dimension of heat affected zone, Micro
Hardness, tissue, etc.
Previous work in the literature clarifies the effect of oxidation dynamics and laser beam velocity on the quality of laser cutting (
Avanish & Vinod, 2008).
This shows that there is an optimal range of cutting speeds for a given material, thickness and laser power.
Surface roughness is an effective parameter to characterize the quality of the machined surface.
Some researchersNagels et al. , 2007)
The results show that the surface roughness value decreases with the increase of cutting speed and frequency, as well as the decrease of laser power and air pressure.
In addition, nitrogen has a better surface finish than oxygen.
Although the available laser power has increased over the past decade, the laser cutting process faces difficulties in cutting thicker parts.
The main problem is the decrease of process stability and the decrease of cutting quality. 2.
The experimental procedure was conducted with a laser system composed of 2800 W continuous C O. sub. 2]laser (Bystronic)
A three-axis CNC workbench with a working volume of 2. 0 m x 1. 5 m x 0. 5 m.
Experiments were carried out on two different materials with thickness of 5, 10 and 15mm.
Table 1 gives the chemical composition of the materials inspected.
Figure 1 gives the geometry of the sample shape. 1. Sample I (EN 10083-3)
It is the preparation of laser cutting using saw and milling machine before.
It is a hot rolled square rod with a size of 140mm x. Sample II (GX40CrNiSi22-10)
Made of tubes produced by centrifugal casting.
The beam profile is close to Gaussian ([TEM. sub. 00])
Beam quality k 【
About equal to]0. 75.
During the whole experiment, other process parameters remained unchanged: laser power 2520 W, lens focal length 127mm, auxiliary nitrogen pressure 14 bar, nozzle diameter 2.
0mm, the focus position below the bottom of the sample.
That is, previous experiments have shown that it is not possible to achieve the cutting of the material under test when oxygen is used as an auxiliary gas.
In previous experiments, the best value and focus position of the auxiliary gas pressure were obtained.
In experiments where the laser is focused on the surface of the plate or even higher than the plate, the results show that the quality of the cutting area is poor. [
Figure 1 slightly]3.
The roughness measurement surface roughness as the cutting quality parameter is analyzed.
Roughness parameters]R. sub. a]--
Measure the average deviation.
Surface roughness is measured by using the device Perthometer concept.
The DIN 2310 standard specifies the measurement of surface roughness at precisely determined depths.
This depends on the thickness of the material.
Due to the specific process and the acquisition of effective results, the measurement is carried out on five parallel lines evenly sorted along the cutting depth, fig. 2.
That is, along the length of the cut, the height of the non-uniformity increases from the top of the cut to the bottom.
The conditional exchange of cross laser beams and materials is the reason, the local rate exchange between as and thermal conductivity and absorption coefficient (
It depends on the temperature exchange). Fig.
2 shows the increase of surface roughness along the cutting depth according to the process parameters and the type and thickness of the material.
During the execution of the experiment, the maximum deviation was 6. 6 [micro]m is obtained. [
In order to obtain effective results, visual selection of samples was made.
No samples containing large floating slag were precipitated. 4.
GX40CrNiSi22-experimental value of parameter roughness Ra at different cutting speeds during laser processing-
Steel is given in Figure 10. 3 and in Fig. 4 of EN 10083-3 steel. [
Figure 3 slightly][
Figure 4 slightly]
It is observed that during C [the surface roughness increases by increasing the thickness of the material while keeping other process parameters unchanged]O. sub. 2]
Laser cutting of two kinds of high alloy steel tested. 5.
Conclusion The experimental study was carried out in this paper, and the effects of cutting speed and material thickness as well as types and pressures of auxiliary gases on surface roughness in the C process were studied [O. sub. 2]
Two different materials are cut by laser.
Based on the results obtained, the following conclusions can be drawn: * once the correct value is determined, a slight change in pressure does not determine the quality of the cut.
Therefore, for different power values, cutting speed and focus positions, and the type and thickness of the test material, the auxiliary gas pressure can remain the same.
* The maximum possible cutting speed depends on the type of material and thickness of the given laser system.
Above this maximum, it is not possible to obtain a recognized level of cutting quality.
* When laser cutting thinner material, the cutting quality is better and the cutting speed range is larger.
In future work, the influencing process parameters in the laser cutting process of high alloy steel for special use will be considered.
These process parameters will be optimized with multiple factors in mind
Cut performance features. 6.
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Laser cutting of carbon/carbon multi-bodylamelled plain-Organizational structure.
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6955 Lamikiz, A. ;
Lopez de LacarN. ; Sanchez, J. A. ; Pozo, D. ; Etayo. J. M. & Lopez. J. M. (2005). C[O. sub. 2]
Laser cutting of advanced high strength steel (AHSS).
242 (Applied Surface Science)April 2005)page numbers (362-368), ISSN: 0169-
4332 Nagels, E. ; Dufloub, J. R.
And J. Humbeeck Van(2007).
Effect of sulfur content on laser quality.
Journal of Materials Processing Technology, 194 ,(November, 2007)page numbers (159-162), ISSN 0924-
0136 Rajaram, N. ; Sheikh-Ahmad, J. & Cheraghi, S. H. (2003). C[O. sub. 2]
Laser cutting quality of 4130 steel.
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