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Tool Materials (Tool Wear (mechanisms (diffusion (depend on (tempertature,…

- - - - oldest
      - for drills taps, broaches, reamers
      - inexpensive, easily shaped, sharpened
      - no sufficient hardness & wear resistance
      - limited to low cutting speed
    - - produced by rolling process & hardness to various depths
      - good wear resistance relatively
      - used in machining low carbon steel materials
      - cutting speeds 25-30 m/min
      - types
        
        T-series
        
        18% tungsten(W), 4% chromium, 1%vanadium, 0.7% carbon, 5% cobalt
        
        less distortion during heat treating
        
        M-series
        
        contains 10% molybdenum, 5% W, chromium, vanadium and cobalt
        
        higher, abrasion resistance
        
        H.S.S. are majorly made of M-series
        
        made due to shortage in W during WW2
      - H.S.S. alloying elements properties at Lec. no. 5 from slide 11 to 20
- - - - fusion of tool material to the chip and the workpiece
      - depend on
        
        tempertature
        
        period of contact
        
        biding affinity between tool mat. and chip
        
        solubility of tool mat. in WP mat.
    - - due to friction mechanism between the chip and tool
    - - hard particles on the underside of the chip pass over the tool face
    - - by oxidation of the tool surface because of temperature of chemical reaction
  - - - reasons
        
        diffusion wear and chemical reaction
      - solutions
        
        select AL2O3 coated grade
        
        select a positive rake angle
        
        reduce the speed
        
        reduce the feed
    - - reasons
        
        cutting speed too high
        
        insufficient wear resistance
        
        feed too low
      - soulotions
        
        reduce cutting speed
        
        select a more wear-resistance grade
        
        increase feed