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METALWORKING EQUIPMENT                                                                                                                                                                                METALWORKING EQUIPMENT
        AND TOOLS                                                                                                                                                                                             AND TOOLS
                                                                                                                                        Fig. 2 shows images of the treated surface                   It seems  promising to use  this
                      Prospective                                                                                                by two different methods. The picture on the left  technology not only for cleaning the surface
                                                                                                                                 (a)  clearly  shows  the  traces  of  «plowing»  and  from  strong  oxide  layers,  but  also  for

           method for pre-                                                                                                       cuts  with abrasive  particles.  These  craters and  preparing the surface before coating. At the
                                                                                                                                 irregularities  significantly  increase  the  surface  first stage, the surface is smoothed using a
          treatment of the                                                                                                       roughness.  On  the  right,  a  subsequent  water- microabrasive  method,  and  at  the  second
                                                                                                                                 jet treatment  was  carried  out.  The surface  is  stage, the surface is cleaned and hardened
         hard alloy before                                                                                                       smoothed and characterized by low roughness.                 with a water jet at a pressure of about 3000

                                                                                                                                        At  MSTU  ''STANKIN''  experiments  were  bar.
                    applying the                                                                                                 carried out on the surface treatment of hard alloy
                                                                                                                                 by the water-jet method. Figure 3b shows that
                                coating                                                                                          the  grooves from  grinding, segregation  of  the
                                                                                                                                 cobalt phase, and contamination disappeared on
                                                           In the  process  of  creating  cutting tools, the                     the surface of the sample.
                                                    preparation of the surface of the tool before applying the
                                                    coating plays an  important  role in order  to increase  its
                                                    durability  and  wear  resistance.  The  preparation  process
        affects  the  microtopography,  integrity  and  surface  finish  of  the  tool  material,  which  in  turn
        affects the adhesion and strength of the coating to the surface. Among the methods of such
        exposure are well known such as microabrasive and water jet.
               Micro-abrasive treatment removes material through the interaction of a jet of air or water
        containing an abrasive with the surface of the material being processed. A microabrasive jet is
        formed by passing a stream of gas or air containing abrasive particles (Al2O3 or SiO2 powder)
        with a size of 10 to 50 microns through an orifice - a nozzle with a diameter of 0.4-1.2 mm -
        under pressure up to 6 bar. The resulting velocity of the transported particles is from 150 to 300
        m / s [1].
               Fig. 1 schematically  shows a microabrasive blasting machine.  If  water  is used as a
                                                                  medium  for  transporting  abrasive  particles,                Fig. 2. Comparison of microabrasive jet and hybrid treatment [5].
                                                                  then the process is called ''wet microabrasive
                                                                  processing''.
                                                                         High  fluid  pressure  water  jetting  is  an
                                                                  extremely  flexible  and  versatile  processing
                                                                  method.  It has  found applications in various
                                                                  industries in processes such as cleaning, surface
                                                                  defect removal, cutting, water jet hardening,
                                                                  material surface modification processes.
                                                                         Water  jet  hardening  is the  process  of
                                                                  mechanically  hardening  a  surface  through
                                                                  the action of high velocity water droplets that
                                                                  cause  local plastic deformation.  As  a  result,
                                                                  significant residual compressive stresses arise
                                                                                                                                                                а
                                                                  in the surface layer, which contribute to an                   Fig. 3. Surface treatment by water-jet method.                                    b
                                                                  increase in surface hardness and fatigue life.
                                                                  Also, the advantages of this method include:
                                                                                                                                                                                                                           Weiss Daniel, PhD student.
         Fig. 1. The basic scheme of microabrasive blasting [3].  the  absence of surface  contamination after                                                          S. V. Fedorov, scientific adviser, candidate of technical sciences, associate professor.
                                                                  processing and the absence of thermal effects                                                                  Department ''Highly efficient processing technologies'' MSTU ''STANKIN''.
                                                                  [4].
                                                                         The hybrid method is a  combination of                  References:
                                                                  micro abrasive blasting and conventional water
        blasting. In [5], this method is proposed as an innovative method for removing the oxide film                            1. C.J.C Rodríguez, Cutting edge preparation of precision cutting tools by applying micro-abrasive jet machining and
                                                                                                                                 brushing, Mesogeometry of the cutting edge. ISBN 978-3-89958-713-5.
        from  the  surface  of  titanium  alloys.  First,  the  method  of  micro-abrasive  blasting is  used  to                2. F.Tikel, Schneidekantenpräparation-Ziele, Verfahren, Methoden. Berichte aus Industrie und Forschung. ISBN 978-3-
        remove the film to the required depth, then ordinary blasting is used to clean the surface from                          89958-494-3.
        abrasives,  level  the  surface,  reduce  roughness,  that  is,  to  achieve  a  ''polishing''  effect.  The             3. Modeling of material removal in mechanical type advanced machining processes: a state-of-art review Neelesh K. Jain,
                                                                                                                                 Vijay K. Jain.
        results showed that a combination of these methods is effective for surface cleaning.                                    4. The Impact of Plain Waterjet Machining on the Surface Integrity of Aluminium 7475 F. Boud, L. F. Loo, P. K. Kinnell.
               In most cases, abrasive particles must be removed from the surface of the work piece,                             5. Parametric effects on grit embedment and surface morphology in an innovative hybrid waterjet cleaning process for alpha
        since such particles can initiate cracks [6], which reduces fatigue strength and, according to                           case removal from titanium alloys.
                                                                                                                                 6. Singh, J. and S.C. Jain, Mechanical Issues in Laser and Abrasive Water-Jet Cutting. Jom-Journal of the Minerals Metals &
        [7],  surface  contamination  with abrasive  particles  can  also  cause  serious  problems  during                      Materials Society, 1995.
        subsequent application coatings for parts and tools.                                                                     7. Chen, F.L., et al., Minimising particle contamination at abrasive waterjet machined surfaces by a nozzle oscillation
                                                                                                                                 technique. International Journal of Machine Tools and Manufacture, 2002.

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