ipg fiber laser cutting speed chartwooden frame mirror full length

This chapter is distributed under the terms of the Creative Commons Attribution 3.0 License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The effects of cutting speed and focal point position on the surface roughness of the fiber laser cut edges are more significant when a short focal length of the focusing optics is used than when longer focal length optics is used. The absorbed energy sets the electrons in forced vibration motion which can be detected as heat. By making research easy to access, and puts the academic needs of the researchers before the business interests of publishers. Consequently, for the same incident laser power, cutting speeds of the reactive fusion cutting using an active (oxygen or compressed air) assist gas are usually higher compared to the inert gas-assisted cutting process. The cut kerf is the opening that is created during through-thickness penetration of a workpiece; therefore, the cut kerf width, w, shown in Figure 2 is the separation distance between the two cut surfaces of the cut kerf which represents the amount of material removed during the laser cutting process.The laser power absorbed at the cutting front is utilized in melting the kerf volume at the rate of cutting and part of the absorbed laser power is lost from the cutting zone through heat conduction to the substrate metal. Professor Veli Kujanp of VTT Technical Research Centre of Finland and Professor Antti Salminen of Lappeenranta University of Technology are acknowledged for the invaluable discussions that inspired the formulation of the ideas presented in this chapter. Absorptivity of the light beam by the metal workpiece generally increases with increase in the temperature of the metallic material. The oxidation of the metal melt during laser cutting is sustained in as much as the reactants - i.e., O2 and molten metal are available in the laser material interaction zone. 0000040608 00000 n 0000002011 00000 n The extent of the exothermic reaction in the cutting front is limited by the flow rate of the rarer type of reactant (either oxygen or iron). Their approach involves splitting up the beams from two single mode fiber lasers and positioning the beams in a pattern in the cut kerf in such a way that there is a melt beam that performs melting and the melt ejection beam. However, the minimum focused spot size is also directly proportional to the focal length (see Equation (2)) such that use of longer focal length optics for focusing of the laser beam results in a larger focused spot size with reduced power intensity. The effects of the processing parameters in the cutting of thick-section stainless steel and mild steel and medium-section aluminium have been reported; optimization of the processing parameters for enhancement of the cut edge quality has been discussed. The laser beam quality is the critical parameter that influences the focusability of the laser beam; Equation (2) gives the relationship between the BPP of the laser beam and the minimum focused spot size, dffor focusing optics of focal length, f, and a raw beam diameter on the focusing optics, D. [3, 15]. This means that the 1.07 m laser light is reflected less, absorbed more easily, and the shorter wavelength can be focused into a spot that is around 1/10th of the diameter of a comparable CO2 beam. The tendency of boundary layer separation and dross adherence on cut edges during thick-section metal cutting using an inert assist gas is influenced by the efficiency of melt removal from the cut kerf. 0000002099 00000 n Fiber Lasers were simply different than their cousin, the CO2 laser resonator. The development in the output power of solid-state fiber laser source has resulted in the increasing interest in the use of the high brightness fiber laser in macro laser material processing applications, especially cutting and welding of metal [1]. 1526 0 obj <> endobj Dross adherence and presence of the boundary layer separation on the laser cut edges which affect the surface roughness characteristic of a laser cut edge are critical quality aspects that need to be considered in thick-section metal laser cutting. Schulz et al. Posted By: Andy Kamashian | Posted On: January 25, 2019. Iron-oxide (FeO) generated in oxygen-assisted laser cutting of mild steel does not boil, but would dissociate when heated to high temperatures; the iron-oxide dissociation process which consumes much energy could lead to a collapse of the cutting process [26]. The dynamic nature of the exothermic oxidation reaction that occurs during reactive fusion laser cutting of mild steel is favored by high oxygen gas pressure resulting in wider non-uniform cut kerfs as shown in Figure 11. 0000007219 00000 n The cutting speeds in reactive fusion cutting are much higher than in fusion cutting with an inert assist gas because of the additional heat added by the exothermic reaction. support team who will be happy to help. They operated much more efficiently, lost far less power from mirrors and lenses then their CO2 counterparts thus put more cutting power to the torch. Increased cutting speeds also result in poor melt ejection at the bottom of the cut kerf, causing dross attachment and in worst cases the eventual resealing of the lower cut edge by the resolidified melt. (#m,-> pQ\QEHQ@Q@Q@Q@Q@R1 Usually, the lower section of the cut edge has a higher surface roughness than the upper section due to the melt build-up at the lower cut section, resulting in inefficient melt removal. The melt surface propagates through the material with a velocity that depends on the energy input, thermal properties of the workpiece material, and the molten material removal mechanisms. 0000032676 00000 n [32] experimentally investigated the effects of different cutting process parameters in the cutting of 610 mm 304 stainless steel using a high brightness ytterbium fiber laser. Consequently, ytterbium fiber lasers delivering over 10 kilowatt power output are now available for materials processing applications [14]. 0000002538 00000 n Only a small proportion of the oxygen jet is consumed in the oxidation reaction as part of the oxygen jet is utilized as drag to accelerate the melt out of the cut kerf while part of it is lost across the top workpiece surface or down the kerf; consequently, only about 50% of the molten iron reacts with the oxygen in the cut kerf. The real world comparisons or, 'Where the Rubber Meets the Road' of Fiber vs CO2 technology is in the cutting speeds and capacities. The economic aspects of laser usage in manufacturing that form important criteria in the choice of a suitable laser system for thick-section metal cutting include: high processing speeds, high processing depths, high cut edge quality, and high wall-pug efficiency of the laser system. SEM image of the boundary layer separation on a 10-mm stainless steel cut edge. ahS@=+)cUj@W__W j59Y / |I W:VD'VI=*/>z u*MtVHF@?:|~T*g 8>)ExitLR>rFzU74P.;zQNRqxx2_NEX ;M%gaI'2h Z(*w85_z7int{r3;ZY-D$K4RM1Yha>. %PDF-1.5 It is shown in Figure 9 that the assist gas pressure does not have an effect on the kerf width in inert gas-assisted laser cutting. The focused high-intensity laser beam radiation that is incident on the surface of a metal workpiece is partly absorbed and partly reflected by the metal surface. The molten metal ejection is mainly driven by the shear force at the assist gasmelt interface and the pressure gradient created in the cut kerf. The use of cladding-pumping in the high-power ytterbium fiber laser limits the thermal issues (i.e., the variation of the refractive index with temperature) that affect the stability of high-power Nd: YAG lasers [6]. Additionally, laser beam combination techniques are also used for power scaling of the ytterbium fiber laser by bundling multiple single-mode fiber laser elements to provide up to 10 kW multi-mode power output. Variation of melt flow velocity and melt film thickness with cut depth for different assist gas pressure. They observed that the cut edge quality in 610-mm stainless steel improved with increase in cutting speeds, higher nitrogen assist gas pressures, and wider cut kerfs. The exothermic oxidation reaction contributes up to 40% of the energy used in the laser cutting of mild steel and stainless steel using oxygen assist gas jet [15]. Near diffraction limited beam quality (i.e., high beam quality denoted by low BPP) is essential for focusing of the laser beam to a small focal spot size to give very high power intensity necessary for processing of thick-section metals at the required high processing speed. Some Laser Fabrication shops take maintenance of their CO2 or fiber laser cutting machine as seriously as they do their bank account. Optimization of the cutting process parameters for enhancement of the cut edge quality in thick-section metal cutting at high cutting speeds using the ytterbium fiber laser has shown that the maximum applicable cutting speed is influenced by the melt removal process. [32] reported that for the cut edge quality in 610- mm stainless steel, the location of the boundary layer separation point moves closer to the bottom cut edge with increase in cutting speed. 0000032216 00000 n Effect of focal point position on the dross adherence on 10-mm stainless steel. to go back to the article page.Or contact our We had the data to prove that increasing your wattage on a machine increased your speed and thus throughput. At Southern Fabricating Machinery Sales, Inc.we know Lasers and whether your in the market for a new or used system, fiber or CO2 we have the knowledge and systems available to help you make the right choice for your Needs AND Budget. The quality of a laser beam is characterized by the beam parameter product (BPP), which is the standard measure of beam quality that incorporates the wavelength effects. The melt film in the cutting front is generated by the melting action of the absorbed laser beam power and the oxidation reaction power (in the case of oxygen or compressed air assist gas). Fiber laser cutting machines are designed for metal fabrication. Wandera et al. The core region of highest refractive index is surrounded by two cladding regions of progressively decreasing refractive index which serve to confine the pump light within the core region. The direct absorption of the beam by the workpiece takes place through the Fresnel absorption mechanism (i.e., absorption during reflection from the surface). And although Fiber Laser cutting is used in many different areas, from medical to Southern Fabricating Machinery Sales, Inc. 10417 South County Road 39Lithia, FL 33547. Therefore, the rate of melt removal from the narrow thick-section cut kerf may be a potential factor limiting the maximum workpiece thickness that can be cut using the high brightness fiber laser rather than the required laser power. Therefore, the materials surface reflectivity, thermal conductivity, and workpiece thickness are the material parameters that critically affect the efficiency of the laser cutting process. We are a community of more than 103,000 authors and editors from 3,291 institutions spanning 160 countries, including Nobel Prize winners and some of the worlds most-cited researchers. The higher energy density loss from the cutting front when cutting at low cutting process increases the tendency of dross adherence on the cut edge. Unfortunately OEMs and Dealers were slow to educate equipment buyers/Manufacturer's of the differences in cutting speeds & capacities thatSolid Stateand Fiber Lasers brought to the table. For many years we as manufacturers, distributors and OEMs of laser cutting systems were taught that Power (KW) IS Capacity& Speed. 1526 22 This provides a dramatically higher power density, making metal cutting easier. In cutting of 10-mm stainless steel using the 4 kW fiber laser power at cutting speed of 1.0 m/min and focal position located on the bottom workpiece surface, dross-free cut edges with lower surface roughness were obtained with the 254-mm focal length optics than when the 190.5-mm focal length optics was used. The near infrared wavelength of the high brightness ytterbium fiber laser offers a higher absorptivity by metals than the CO2 laser. Multiple reflections of the incident laser beam inside thick-section cut kerfs result in increased absorption of the beam inside the cut kerf; consequently, the maximum temperature in the cutting front occurs below the material surface. The cut kerf width is usually a fraction of a millimeter and the molten metal has a high viscosity such that the melt flow can be assumed to cover the entire cut kerf. w !1AQaq"2B #3Rbr Often Fabricators are stuck in a rut of manufacturing. The cut edge quality improved with increase in cutting speeds. [23] developed a theoretical model to estimate the power requirement for melting the kerf volume and the inevitable conduction power losses. For cutting of a specific metal of a given thickness, the cutting process parameters can be altered by the operator so as to optimize the cutting process and obtain high cut quality at an optimal cutting speed for high productivity. [24] developed an analytical approximation of the heat conduction losses during laser cutting of metals and provided an expression that can be used to estimate the temperature change in the substrate metal during laser cutting; the temperature change in the substrate metal is inversely proportional to the Peclet number which is directly proportional to the cutting speed. 2016 The Author(s). Our team is growing all the time, so were always on the lookout for smart people who want to help us reshape the world of scientific publishing. Technically speaking Fiber lasers have a different emission wavelength of around 1.07 m, compared to traditional CO2 lasers that emit the beam at 10.6 m. [23, 31] and Wandera and Kujanp [29], also experimentally investigated the effects of process parameters in the cutting of 10-mm stainless steel, 15-mm mild steel, and 4-mm aluminum using the high brightness fiber laser. Wandera et al. In reactive fusion cutting of thick-section metal, the proportion of the kerf volume that is vaporized is considered to be negligible due to the high conduction losses which scale up with increase in workpiece thickness. Among the rare earth ions used in fiber lasers, ytterbium is highly absorbing of pump radiation and is preferred as doping material for the high-power fiber laser operating at 1,0601,080 nm spectral range and delivering kilowatt output power suitable for material processing [2]. Wandera and Kujanp [35] established the cutting process parameter combinations for optimization of the cut edge quality in 10-mm stainless steel workpiece. %&'()*456789:CDEFGHIJSTUVWXYZcdefghijstuvwxyz The melting efficiency of a given laser increases with increase in the absorptivity since a larger proportion of the incident laser radiation is absorbed by the material and utilized in melting of the kerf volume during cutting. How? Sparkes et al. Maximum cutting speed at a given laser power level and efficient melt removal for prevention of the undesired dross adherence on the cut edge can be achieved through optimization of the cutting process parameters. Therefore, the improved cooling mechanism in the ytterbium fiber laser has enabled the solid-state laser to achieve near diffraction limited beam quality at high output power [3]. The principle role of the inert assist gas jet e.g., nitrogen during laser cutting of a metal workpiece is to eject the molten metal to create the cut kerf. Conduction limited welding occurs when the power density is not sufficient to cause evaporation of part of the melt at the given welding speed. The characteristic gas velocity, Ug, inside the cut kerf is estimated using the Bernoulli equation as presented in Equation 9. Contact our London head office or media team here. The speed of penetration of a metal workpiece during laser cutting depends on the absorbed incident laser power intensity. When cutting thick-section stainless steel using the fiber laser, optimum cut edge quality is obtained when the focal position is located on the lower surface of the workpiece as long as the power intensity is sufficient to penetrate the workpiece at the applied cutting speed; in this case, the applied cutting speed should be lower than the maximum achievable speed for the applied laser power. [32] reported an increase in fiber laser cutting speeds of up to 1.5 times higher than the CO2 laser cutting speeds. Therefore, the cutting process parameters that affect the power intensity at the cutting front and the gas dynamics in the narrow thick-section cut kerf have a great bearing on boundary layer separation, dross adherence, and the resultant cut edge surface roughness. Using 5 kW fiber laser power, stainless steel of 10-mm thickness can be cut at a maximum cutting speed of 1.5 m/min with nitrogen assist gas jet and mild steel of 15-mm thickness can be cut at a cutting speed of 1.8 m/min with oxygen assist gas jet. endstream endobj 1527 0 obj<> endobj 1528 0 obj<> endobj 1529 0 obj<>/ColorSpace<>/Font<>/ProcSet[/PDF/Text/ImageC/ImageI]/ExtGState<>>> endobj 1530 0 obj[/ICCBased 1537 0 R] endobj 1531 0 obj[/Indexed 1530 0 R 0 1538 0 R] endobj 1532 0 obj<> endobj 1533 0 obj<>stream Effect of assist gas pressure on the location of boundary layer separation point and kerf width in inert gas-assisted laser cutting, Variation of surface roughness with assist gas pressure for the fiber laser cut edges in 10-mm stainless steel and 4-mm aluminum, Effect of oxygen assist gas pressure on the kerf width and striations. The surface reflectivity limits the amount of laser energy coupled to the workpiece; therefore, metals with high surface reflectivity e.g., aluminum require higher power intensity for cut initiation. Andy has extensive experience in Machining as well as Metal Fabricating. However, the plasma buildup is not very significant in cutting due to the assist gas which blows it away; therefore, plasma absorption mechanism is very limited in laser cutting. Submitted: May 11th, 2015 Reviewed: November 19th, 2015 Published: March 2nd, 2016, Total Chapter Downloads on intechopen.com. The melt flow velocity increases with increase in assist gas pressure and increase in the cut kerf width, resulting in a reduction in the melt film thickness. Thus, the quality of the cut depends on the quantity of the melt which builds up in the cut kerf and causes dross on the cut surface. 0000004494 00000 n 0000004097 00000 n Plasma absorption occurs through absorption of the laser beam by the free electrons in the plasma (i.e., hot metal vapor) leading to plasma re-radiation [15]. Fiber Lasers - Why the Kilowatt is not the King, Southern Fabricating Machinery Sales, Inc. stream Molten metals that have high surface tension and high viscosity are more difficult to remove from the cutting front and have a high tendency to attach on the underside of the cut as dross. Effect of assist gas pressure on the location of the boundary layer separation point and dross attachment on cut edges in inert gas-assisted laser cutting. In fiber laser cutting of 15-mm mild steel using oxygen assist gas, the best cut quality was obtained with a 1.5-mm nozzle diameter and the 2.5-mm nozzle diameter produced the worst cut edge quality [23]. The efficiency of melt ejection is influenced by the nozzle diameter which determines the amount of the cutting gas jet available at the cutting front. Due to the reduction in the proportion of the absorbed laser beam that is lost through conduction to the substrate metal with higher cutting speeds, the potential increase in cutting speed when using the high-power ytterbium fiber laser increases the melting efficiency because the conduction energy losses from the cutting front decrease with increase in cutting speed. As PhD students, we found it difficult to access the research we needed, so we decided to create a new Open Access publisher that levels the playing field for scientists across the world.