Article
Influence of Process Parameters on Cutting Width in CO
2
Laser
Processing of Hardox 400 Steel
Constantin Cristinel Girdu
1
, Catalin Gheorghe
2,
* , Constanta Radulescu
3
and Daniela Cirtina
4
Citation: Girdu, C.C.; Gheorghe, C.;
Radulescu, C.; Cirtina, D. Influence of
Process Parameters on Cutting Width
in CO
2
Laser Processing of Hardox
400 Steel. Appl. Sci. 2021, 11, 5998.
https://doi.org/10.3390/app11135998
Academic Editor: João Carlos de
Oliveira Matias
Received: 23 May 2021
Accepted: 24 June 2021
Published: 28 June 2021
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1
Department of Manufacturing Engineering, Transilvania University of Brasov, Eroilor Street 29,
500036 Brasov, Romania; girdu.constantin.cristinel@unitbv.ro
2
Department of Engineering and Industrial Management, Transilvania University of Brasov, Eroilor Street 29,
500036 Brasov, Romania
3
Department of Industrial and Automatic Engineering, Constantin Brancusi University of Târgu Jiu, Eroilor
Street 30, 210135 Targu Jiu, Romania; c.radulescu@utgjiu.ro
4
Department of Sports and Health, Constantin Brancusi University of Târgu Jiu, Eroilor Street 30,
210135 Targu Jiu, Romania; daniela@utgjiu.ro
* Correspondence: gheorghe.c@unitbv.ro
Abstract:
This paper presents an experimental research that proposes to determine the influence
of process parameters on CO
2
laser cutting of 8 mm thick Hardox 400 steel, for which Kerf has a
minimum value. The experimental research was conducted according to a complete factorial plan
with laser power, assistant gas pressure and cutting speed as the input parameters, and cutting width
as the dependable variable. The Design of Experiment (DOE) consisted of 27 references and was
completed with four replicas to determine the variation of the Kerf average. Functional, linear and
quadratic relations were determined, which describe the Kerf dependence on the cutting parameters
in order to establish the most influential parameter. The results show that the independent parameter
with the most significant influence was the laser power, with minimum Kerf obtained if the laser
power and the assistant gas pressure were adjusted to average values. The interaction between laser
power and auxiliary gas pressure at constant cutting speed was investigated to improve Kerf and
reduce the laser processing cost. The study offers the right combination of process parameters that
leads to a minimum value of the cutting width.
Keywords: laser cutting; Hardox 400 steel; kerf; ANOVA; RSM; CO
2
laser
1. Introduction
The extension of laser beam cutting (LBC) as a cutting process in industrial processes
is due to the advantages it generates. Laser beam processing allows for cutting a wide
range of materials with different mechanical properties. The optimization of the cutting
parameters, which results from the concentration of the laser beam in a very small point,
on the surface of the material to be processed, will lead to faster processing of various
materials with lower processing costs.
The use of laser in cutting and processing metallic materials has been researched
in many specialized works. Tatzel et al. showed the effect of the focusing position on
the induced heat affecting the laser-cut edges of 3-mm-thick stainless steel. The process
parameters observed during cutting were speed, assistant gas pressure and focusing
position. The latter has proven to be an important parameter if a high processing quality
is to be achieved [
1
]. Levichev et al. shows that continuous heating of the semifinished
part during oxygen-assisted cutting decreases the quality and generates material losses
to thick metal plates, where the cutting speed is low. The cutting experiments took place
on a soft steel with a thickness of 15 mm using a 4 KW power laser. Three methods
were used to obtain high quality of the cut surface: optimizing the input parameters for
preheated areas, using active cooling to eliminate heat excess and using active cooling
Appl. Sci. 2021, 11, 5998. https://doi.org/10.3390/app11135998 https://www.mdpi.com/journal/applsci
