Non-Traditional Machining & Thermal Cutting Processes

Non-Traditional Machining & Thermal Cutting Processes

1. Mechanical Energy Processes

   • Types
     • Water Jet
       • Cutting (WJC)
     • Abrasive Jet
       • High Velocity stream of gas containing small abrasive particles
       • -Processes are dangerous - nano-size particles can cuase health issues such as cancer -Usually performed in container filled with liquid
       • Usually Manual Job
       • Normally finishing process rather than cutting
       • Applications
         • Deburring
         • trimmiing
     • Abrasive flow machining
     • Electromechianical
       • Group of processes in which electrical energy is used in combination with chemical reactions to remove material
       • Material removal by anodic dissolution, using electrode (the tool) in close proximity to work but separated by a rapidly flowing electrolyte
       • Reverse of electroplating
       • Work material must be a conductor
       • Types
         • Machining (ECM)
         • Deburring (ECD)
           • Adaptation of ECM to remove burrs or sharp corners on holes in metal parts produced by conventional through-hole drilling
         • Grinding (ECG)
           • Special form of ECM in which grinding wheel with conductive bond material augments anodic dissolution of metal part surface
           • Applications
             • Sharpening of cemented carbide tools Grinding of surgical needles and other thin-wall tubes and fragile parts
       • Operation
         • Material is deplated from anode workpiece (positive pole) and transported to a cathode tool (negative pole) in an electrolyte bath
         • Materials
       • Physics
         • V = C*I*t
           • V = Volume
           • C = specific removal rate
           • I = current
           • t = time
       • Applications
         • Die sinking
         • Multiple Hole Drilling
         • Holes that are not round
         • Deburring
     • Thermal Energy
       • Overview
         • -Very high local temperatures --Material is removed by fusion or vaporization -Physical and metallurgical damage to the new work surface -In some cases, resulting finish is so poor that subsequent processing is required
       • Types of processes
         • Electric Discharge
           • Metal removal by a series of discrete electrical discharges (sparks) causing localized temperatures high enough to melt of vaporize the metal
           • Machining
             • -Work materials must be electrically conducting -Hardness and strength of work material are not factors - Material removal rate depends on the melting point of work material
             • Applications
               • -Tooling for many mechanical processes: molds for plastic injection, extrusion dies, wire drawing dies,
             • Wire EDM
         • Electron Beam
           • Machining (EBM)
             • Uses high velocity stream of electrons focused on workpeice surface to remove material by melting and vaporization
             • Operation
               • -EB gun accelerated a continuous stream of electrons to about 75% of light speed -Beam is focused through electromagnetic lens, reducingdiameter to as small as 0.025mm (0.001 in) -On impinging work surface, kinetic energy of electrons is converted to thermal energy of extremely high density which melts or vaporizes material in a very localized area
             • Applications
               • -Works on any material -Ideal
         • Laser Beam
           • Machining
             • Uses the light energy from a laser to remove material by vaporization and ablation
             • -Laser = light amplification by simulated emission of radiation --Laser converts electrical energy into a highly coherent light beam with the following properties: ---Monochromatic (single wave length) ---Highly collimated (light rays are almost perfectly parallel/) -These properties allow laser light to be focused, using optical lenses, onto a very small spot with resulting high power densities
             • Applications
               • Drilling
                 • Small holes
                   • Down to 0.025mm (0.001 in)
               • Slitting
               • Slotting
               • Scribing
               • Marking
               • Used on small/thin stock
         • Plasma Arc Cutting
           • Uses plasma stream operation at very high temperatures to cut metal by melting
           • Operation
             • -Plasma is a superheated