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Analysis and optimization of surface quality of stainless steel miniature gears manufactured by CO2 laser cutting

  • Authors: Anghel, Cristina , Gupta, Kapil , Jen, T.C.
  • Date: 2020
  • Subjects: Gear , Laser , Machining
  • Language: English
  • Type: Article
  • Identifier: http://hdl.handle.net/10210/411159 , uj:34540 , Citation: Anghel, C., Gupta, K. & Jen. T.C. 2020. Analysis and optimization of surface quality of stainless steel miniature gears manufactured by CO2 laser cutting.
  • Description: Abstract: This paper reports the results of investigation conducted on CO2 laser cutting of miniature gears of stainless steel 304. In this work, analysis of the effects of important laser parameters such as power, cutting speed, focal position, and gas pressure on average surface roughness (Ra) has been investigated. Stainless steel spur gears having 9.04 mm outside diameter and 4.5 mm face width have been cut using a CO2 laser system with nitrogen as assisted gas. A total of twenty nine experiments have been conducted based on BBD (Box-Behnken Design) technique of response surface methodology where aforementioned laser parameters varied at three levels each. ANOVA study found focal position as the most significant parameter. Further, the Desirability based optimization of laser parameters obtained best values of Ra- 0.43 µm at laser power- 2407 W, cutting speed- 1.25 m/min, focal position- (-) 2.4 mm, gas pressure- 12.5 bar. A scanned electron microscopy study also revealed the good surface morphology of the miniature gear machined at optimum parameters.
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Effect of built orientation on direct metal laser sintering of Ti-6Al-4V

Laser therapy for the treatment of onychomycosis : best evidence based practice or not?

  • Authors: Dembskey, Nadia , Abrahamse, Heidi
  • Date: 2016
  • Subjects: Onychomycosis , Resistance , Laser
  • Language: English
  • Type: Articles
  • Identifier: http://hdl.handle.net/10210/241789 , uj:24924 , Citation: Dembskey N, Abrahamse H (2016) Laser Therapy for the Treatment of Onychomycosis: Best Evidence Based Practice or Not?. Clin Res Foot Ankle 4: 211. doi:10.4172/2329-910X.1000211 , ISSN: 2329-910X
  • Description: Abstract: Onychomycosis is a very common condition that accounts for 50% of all nail pathologies. Currently 2–5% of the world population suffers from this disorder. It is primarily caused by dermatophytes, but the infection can also be caused by yeasts and non-dermatophyte moulds. Onychomycosis is a therapeutic challenge and recently there has been an increase in resistance to oral and topical antifungal agents, leading to 20–25% relapse and/or reinfection rate. During the past 5 years, the emergence of laser therapy has been the topic of discussion as a newer, safer modality of treatment. Nail clippings and scrapings are the most common methods of sampling for suspected onychomycosis. The simplest method for detecting fungi is by way of 20% potassium hydroxide (KOH) preparations, but lately show insufficient sensitivity in onychomycosis – as much as 40–68%. Fungi can also be grown in culture form; however a 70% sensitivity detection failure rate is seen. Recently, histological fungal detection – in the form of Periodic Acid- Schiff (PAS) stain – has shown high sensitivity at 92% in the detection of fungal elements. The exact mechanism of action of laser is unknown but it is believed that heat disintegrates fungal structures. One of the most appealing characteristics of laser therapy is its ability to deliver energy to the target tissue and avoid systemic side effects at the same time. In 2009 the United Kingdom (UK) Podiatry magazine Podiatry Now published a letter suggesting laser treatment was “possibly the most radical development in the treatment of onychomycosis our profession has ever seen”, although concerns were raised over the unproven efficacy and investment costs involved. Papers have been published investigating the efficacy of lasers for the treatment of onychomycosis. Even though laser therapy provides an alternative option with rapid procedure duration, conflicting evidence is shown in a variety of papers and studies with longer follow-up periods suggest onychomycosis relapse in those treated with laser, which warrants further investigation.
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On Surface Morphology of Miniature Gears of Stainless Steel Manufactured by CO2 Laser Cutting

  • Authors: Gupta, Kapil
  • Date: 2020
  • Subjects: Gear , Laser , Miniature
  • Language: English
  • Type: Article
  • Identifier: http://hdl.handle.net/10210/411343 , uj:34563
  • Description: Abstract: In this research, CO2 laser cutting process is used to manufacturing miniature gears of stainless steel 304. The aim of this research is to study the influence of laser process parameters i.e. laser power, gas flow pressure, laser scan rate and focal position on surface quality of the laser machined miniature gears. The field emission scan electron microscope (FESEM) is used to analyse the different regimes of machined surface and white light spectroscope for 3D surface profile mapping. The laser power is the predominant input factor for surface wear and it was in the form of surface oxides at high voltage of 2500W. In addition to surface analysis, the effect of laser heat source over the gear profile is also studied. The transformation in the microstructure of the gears is observed with metallurgical microscope following standards. The effect of heat source has produced twin in grain structure and lead to surface hardness. Optimal laser power of 2000 W with a scan rate of 2mm/min has produced best gear profile than other combinations.
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Experimental evaluation of surface quality characteristics in laser machining of nickel-based superalloy

  • Authors: Khan, Adam M. , Gupta, Kapil
  • Date: 2019
  • Subjects: Kerf , Laser , Microstructure
  • Language: English
  • Type: Article
  • Identifier: http://hdl.handle.net/10210/404309 , uj:33902 , Citation: Khan, A.M. & Gupta, K. 2019. Experimental evaluation of surface quality characteristics in laser machining of nickel-based superalloy.
  • Description: Abstract: This paper reports the investigation results of CO2 laser cutting of Inconel 718 superalloy. Investigation on the effects of the two important laser parameters power and travel speed on machinability i.e. material removal rate, kerf wall inclination, and average surface roughness of Inconel 718 has been conducted. Increased kerf wall inclination has been found with slow travel speed and increasing power. Low power and high travel speed produced maximum material removal rate and minimum surface roughness. Premature state of fusion has advanced dross regime at a slow cutting speed of 3.3 m/min and leading to a surface roughness of 9.3 microns maximum. Dendrite structures were formed and changes in surface hardness were observed due to high travel speed. Therefore, based on the investigation, slow travel speed with appropriate laser power is recommended for the improved machinability and surface quality of Inconel 718 superalloys.
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Effect of build direction on the microhardness and dry sliding wear behaviour of laser additive manufactured Ti-6Al-4V

Investigation on laser beam machining of miniature gears

  • Authors: Popa, C. , Gupta, K. , Mashamba, A. , Jen, T. C.
  • Date: 2018
  • Subjects: Laser , Miniature gear , Precision
  • Language: English
  • Type: Conference proceedings
  • Identifier: http://hdl.handle.net/10210/279304 , uj:29994 , Citation: Popa, C. et al. 2018. Investigation on laser beam machining of miniature gears.
  • Description: Abstract: Micro‐machining has become a fast growing field in the global manufacturing sector due to increasing demand of miniature machines and devices. The trend involves the fabrication of precision miniature parts that have widespread applications in many areas such as, electronics, biomedical, aerospace, robotics, automobiles and consumer products. Miniature gears are essential components of miniaturised devices such as miniature motors and pumps, scientific instruments, medical equipment, timing devices, and robots etc. These gears are generally fine‐pitched gears running at very high speed, mainly used for transmission of motion and/or torque. Therefore, minimum running noise, accurate motion transfer and long service life are the required qualities of these gears. Considering that a laser beam is capable of cutting complex shapes with great precision and little waste, motivates its use to machine small sized parts including miniature gears. This article reports on the fabrication of stainless steel miniature gears by laser beam machining (LBM) process. A total of twenty experiments have been conducted following one factor at a time design of experiment strategy on CO2 laser machine. The fabricated gears have 9 mm pitch diameter, 10 teeth, and 4.5 mm thickness. The effects of laser machining parameters on surface roughness (mainly average roughness ‘Ra’ and mean roughness depth ‘Rz’) of gears have been analysed. The best quality miniature gear fabricated by LBM possesses 1.04 μm average roughness and 5.797 μm mean roughness depth at par with that obtained by conventional and other advanced processes of miniature gear manufacturing. Investigation reveals that LBM is capable to produce miniature gears of good surface finish and integrity ensuring their high functional performance and long service life. The outputs of this preliminary work encourage further exploration of LBM to establish it as an alternative process for fabrication of precision miniature gears.
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