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INIZIO_TESTO_DA_INDICIZZARE

RESEARCH PROGRAM

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Research Units
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Scientific and education field classification
International Patent Classification
  • HUMAN NECESSITIES
    • MEDICAL OR VETERINARY SCIENCE; HYGIENE
      • FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS (dental prosthetics A61C)
  • PERFORMING OPERATIONS; TRANSPORTING
  • PHYSICS
    • MEASURING (counting G06M); TESTING
      • MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS (measuring human body, see the relevant places, where such exist, e.g. A41H1/00, A43D1/02, A61B5/103; measuring appliances combined with walking-sticks A45B3/08; sorting according to dimensions B07; tool-setting or drawing instruments not specially modified for measuring B23B49/00, B23Q15/00 to B23Q17/00, B43L; combinations of measuring devices with writing-appliances B43K29/08; geodetical, nautical or aeronautical measuring, surveying, rangefinding G01C; photogrammetry G01C11/00; measuring force or stress, in general G01L1/00; investigating or analysing particle size, investigating or analysing surface area of porous material G01N; measuring position, distance or direction, in general, by reception or emission of radiowaves or other waves and based on propagation effects, e.g. Doppler effect, propagation time, direction of propagation G01S; geophysical measuring G01V; measuring length or roll diameter of film in cameras or projectors G03B1/60; combinations of measuring devices with means for controlling or regulating G05; methods or arrangements for converting the position of a manually-operated writing or tracing member into an electrical signal G06K11/00; measuring elapsed travel of recording medium in recording and playback equipment, sensing diameter of record in autochange gramophones G11B; means structurally associated with electric rotary current collectors for indicating brush wear H01R39/58; indicating consumption of electrodes in arc lamps H05B31/34)
Geographical classification
Bibliografia
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[4] Com-Nougué and Kerrand (1985).Laser transformation hardening of chromium steels:correlation between experimental results and heat flow modelling, Proc of the Mat Proc Symp (ICALEO '84). Toledo: LIA, pp 112-119.
[5] Doong, Chen and Tan.(1989).Effect of laser surface hardening on fatigue crack growth rate in AISI-4130 steel. Engineering Fracture Mechanics, 33,(3), pp 483-491.
[6] Eberhardt (1983).Survey of high power CO2 industrial laser applications and latest developments.In: Kimmitt, Proc of the 1st Int Conf on Lasers in Man. Bedford: IFS Publications. pp 13-19.
[7] Gregson (1988). Hardness and hardness vs depth for laser heat treated AISI 4340 steel.In: Ream. Proc of the 6th Int Congr Appl of Lasers and Electro-optics (ICALEO ), Bedford: IFS PubIications. pp 169-177.
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[10] Ion, Moisio, Pedersen, Sorensen and Hansson (1991).Laser surface modification of a 13.5% Cr 0.6% C steel. J of Mat Sci, 26, pp 43-48.
[11] Kawasumi (1978).Metal surface hardening C02 laser. Technocrat, 11,(6), pp 11-20.
[12] Li, EasterIing and Ashby (1986).Laser transformation hardening of steel-II. Hypereutectoid steels. Acta Met, 34,(8), pp 1533-1543.
[13] Sandven (1981).Laser surface transformation hardening. In: Met Handbook. 9th ed. Metals Park: ASM. pp 507-517.
[14] Seaman (1986).Laser heat-treating. In: Belforte, D. and Levitt, M. eds The Industrial Laser Annual Handbook. Tulsa: PennWell Books, pp 147-157.
[15] Seaman and Gnanamuthu (1975).Using the industrial laser to surface harden and alloy. Met Progr, 108,(3), pp 67-74.
[16] Stanford (1980).Lasers in metal surface modification. Met, 47,(3), pp. 109-116.
[17] Steen and Courtney (1979).Surface heat treatment of En 8 steel using a 2 kW continuous-wave C02 laser. Met Tech, 6,(12), pp 456-462.
[18] Yang, Jana and Tam (1990).Laser transformation hardening of tool steel specimens. J of Mat Proc Tech, 21, pp 119-130.
[19] Yessik and Scherer (1981).Practical guidelines for laser surface hardening. In: Metzbower, E. ed. Source Book on Applications of the Laser in Metalworking. Metals Park: American Society for Metals. pp 219-226.
[20] Amende (1984).Transformation hardening of steel and cast iron with high-power lasers. In: Koebner, K. ed. Ind Appl of Lasers. Chichester: John Wiley & Sons. pp 79-97.
[21] Fouquet, Nicot, Renaud and Merlin (1990).Laser surface hardening of a pearlitic grey cast iron. In: Mordike, B. and Vannes, A.B. eds Proc of the 6th Int Conf on High Power Laser Appl. Gournay-sur-Marne: IITT-International. Pp 73-78.
[22] Fukuda, Kikuchi, Yamanishi and Kiguchi (1985).Laser hardening of spheroidal graphite cast iron minimizes distortion while increasing wear resistance. Industrial Heating, 52,(3), pp 41-43.
[23] Trafford, Bell, Megaw and Bransden (1983).Laser treatment of grey iron. Met Tech, 10, pp 69-77.
[24] Wick, C. (1976). Laser hardening. Manuf Eng, 76,(6), pp 35-37.
[25] Wiesner and Eckstein (1987).Laser hardening of steel and cast iron. Weld Inter, pp 986-987.
[26] Creai (1980a).Laser specialist discovers boom market in heat treating. Heat Treating, 12,(12), pp 24-27.
[27] Creai (l980b).Research institute cuts risks in shopping for lasers. Heat Treating, 12,(12), pp 20-22.
[28] Kikuchi, Hisada, Kuroda and Moritsu (1981).The influence of laser heat treatment technique on mechanical properties. In: Proc of the 1st Int Laser Conf (lCALEO), Anaheim, CA, USA. Toledo: Laser Institute of America.
[29] Lopez, Fernandez, Be1lò, Ruiz and Zubiri (1995).Influence of previous structure on laser surface hardening of AISI 1045 steel. ISJL Int, 35,(II), pp 1394-1399.
[30] Mathur and MoIian (1985).Laser heat treatment of cast irons-optimization of process variables: part I. Trans of the ASME, 107,(7), pp 200-207.
[31] Merrien, Lieurade, Theobalt, Baudry, Puig and Leroy (1992).Fatigue strength of laser beam surface treated structural steels. Surf Eng, 8,(I), pp 61-65.
[32] Molian and Mathur (1986).Laser heat treatment of cast irons - optimization of process variables part II. J of Eng Mat Tech, 108, pp 233-239.
[33] Taylor (1979).Heat treatment hots up with lasers. Metalworking Production, 123,(9), pp 138-142.
[34] Ion (2005).Laser Processing of engineering materials-principles, procedure and industrial application, Elsevier.
[35] Amende (1989).Surface treatment of machine tools and automobile components with a laser. VDI-Z, 131,(6), pp 80-83.
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[38] Bransden, Gazzard, Inwood and Megaw (1986).Laser hardening of ring grooves in medium speed diesel engine pistons. Surf Eng, 2,(2), pp 107-113.
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[40] Gutu, Mihiailescu, Comaniciu, Draganescu, Denghel and Mehlmann (1983).Heat treatment of gears in oil pumping units redactor, Proc of the Conf Ind Appl of Laser Tech Vol. 398. Bellingham: SPIE. pp 393-397.
[41] Howes (1993).Laser system for heat treating gears. Proc of the Int Conf Beam Proc of Ad Mat Metals Park: The Minerals, Metals and Materials Society. pp 229-245.
[42] McKeown, Steen and McCartney (1990).Laser transformation hardening of engine valve steels. Proc of the Laser Mat Proc Conf (ICALEO). Orlando: LIA. pp 469-479.
[43] Miller and Wineman (1977).Laser hardening at Saginaw steering gear. Met Prog, 111,(5), pp 38-43.
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[45] Strong (1983).How General Motors decided to heat-treat with lasers on the assembly line. Laser Focus, 19,(11), pp 172-180.
[46] Yessik and Schmatz (1975).Laser processing at Ford. Met Pr, 107,(5), pp 61-66.
[47] Capello and Previtali (2005).Effect of overlapping quote, focus height and beam velocity in the optimization of line laser hardening. VII AITEM Conf, Lecce (1).
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Keywords
SURFACE TREATMENTS, LASER HEAT TREATMENTS, NEAR NET SHAPE, OPTIMISATION OF MANUFACTURING PROCESSES, CONTROL OF MANUFACTURING PROCESSES

EKLAST - Enhancing the Knowledge of LAser Surface Treatments

Politecnico di Milano
Abstract
In the last years the adoption near net shape manufacturing processes is a must in the reduction of production costs and in the re-gaining by western countries of competitive margins on emerging countries. In this frame laser heat treatments offer a big opportunity: since they do not require a cooling liquid and since they can treat very limited areas, in principle they could be integrated in a machining system (i.e. a machining centre for chip removal) that, once terminated the material removal phase, is able to perform the heat treatment of the part directly on board. This would allow to obtain a near net shape part, or even a finished part, with only one machining system and one placement, with evident technical and economical benefits. This possibility is now even closer than in the past thanks to the relatively recent availability of diode lasers, which present an optimal energetic coupling with metals and can be delivered in optical fibres.
Therefore, even though there is an evident industrial interest for this kind of laser application, to date no commercial machining system (Italian or foreign) is equipped with a laser devoted to the on-board heat treatment, despite the great relevance that Italy has at worldwide level in the production of machining centres in general and of laser system in particular.
This is not due to an engineering phase of the product “machining centre” still to be carried out, but is mainly due to a lack of >>>

Principal Investigator
Edoardo Capello Politecnico di MILANO
Research Objectives
The reduction of production costs is one of the most important competitive factors in the new international scenario. One of the ways in which such cost reduction could be obtained is the adoption of near net shape manufacturing processes, that is processes being able to obtain the finished part with a limited number of manufacturing steps, with a minimum number of placements and with a reduced production time.
Being extremely selective and not invasive at all (i.e. that leads to limited distortions), laser heat treatment could represent an important step in that direction. It is not so far away the possibility of having a manufacturing system (i.e. a machining centre) for the production of near net shape parts that can perform the laser heat treatment directly “on board”. In particular, it’s possible to think to a machining centre that, once the chip removal operations are finished, selects the “laser” tool from the tool crib and performs the final heat treatment, therefore producing a finished part.
Nowadays this possibility is still closer thanks to the relatively new diode lasers that are complementary to (and in many cases have substituted) the “old” CO 2 lasers. Diode lasers are of small dimensions and allow the transmission of the beam in an optical fibre; therefore they can be easily integrated in a compact and fairly inexpensive manufacturing system. Moreover, thanks to the short emitted wavelength (which is in the >>>

Timescale
24 months
National and international background
As known, laser heat treatments have been extensively and intensively studied in the past. In particular, in the period from around 1970 till the early 90s several studies have been published in international reviews. Those papers represent the scientific and theoretical bases for this process and: the metallurgical aspects have been analysed and several thermal models were proposed to predict the thermal field as a function of process parameters [1-19].
All this research effort has led to the understanding that the fast heating of a surface layer leads to an extremely large thermal gradient between the surface layer and the bulk that generates a rapid cooling rate. The laser treatment can be extremely localised (only the area exposed to the beam undergoes the microstructural transformation) and can be performed without any movement between the beam and the workpiece if the area to be treated is small. For larger areas the beam can be moved over the workpiece (or viceversa), therefore generating a treatment “track”. For even larger areas it is possible to perform a multi-track treatment that consists in the execution of several adjacent tracks (see Figure (2)).




Figure (2) – Execution of the laser treatment as a function of the extension of the area to be treated: without movement (left), single track (centre) and multi-track (right).



In this period it was understood that laser heat >>>