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 DR-80/85 Applications

 

    For rough and semi-finish turning, milling, grooving and boring of hardened     ferrous and certain softer ferrous materials:-
  • Martensitic cast irons - Ni-hard - High chrome Chilled and heat treated cast irons
  • Fully hardened cold-work  tool steels
  • Bearing steels
  • High speed steels (continuous cutting only)
  • Martensitic stainless steels
  • Cobalt and nickel based hard facing alloys
  • Fully pearlitic grey cast iron

 

   Applying DR-80 & DR-85

    
     DR-80 & DR-85 are high CBN content materials, diffusion bonded at the manufacturing stage to a tungsten
    carbide substrate. This substrate enables flexibility in tool fabrication,  making  it possible to apply a high
    PCBN content material where the solid indexable format of DR-100 is not suitable.
    PCBN cutting tools machine hardened steels with apparent ease because, using relatively high surface
    speeds, heat is generated at the point of cutting so that the PCBN tool cuts locally softened material. The
    heat is carried away from the workpiece by the chip, which rapidly air-cools to provide a brittle and
    harmless swarf, and the CBN tool, which has a high thermal  conductivity. This leaves the component cool,
    with its hardness unaffected.
 
    Cutting forces are generally of the order experienced by hard metal cutting tools machining soft steel. High CBN is
    employed as a semi-finishing or roughing tool using negative rake geometry wherever possible.DR-80 & DR-85 are
    commonly used to produce grooving tools, threading tools and form tools. DR-80 & DR-85 are not as effective as
    DR-100, when operating under ideal conditions, but can often provide a compromise solution.
 
    Although DR-80 & DR-85 are tough, vibration or deflection will result in reduced tool life and poor quality components.
    While they have been used on some very antiquated machines with excellent results, rigidity is essential for success.
    Tool holders should be as large as possible and in good condition. Coolant has little effect on the cutting mechanism
    since the heat generated in the shear zone is sufficient to vaporise any coolant provided.
 
    Coolant does, however, serve two major purposes:-
 
    If a substantial amount of material is to be removed, and a number of passes will be required, or any heating of the     component will make measuring the part difficult, coolant can be used to stabilize the temperature of the workpiece.
 
    Coolant can be used to drive the swarf away from the shear zone where it might interfere with the cutting edge.
    Coolant should not be used for interrupted cutting any hardened materials.
 
    DR-80 is (80% CBN) has a greater particle size than DR-85, (85% CBN). DR-80 is better for  hardened
    steel, but DR-85 has  better wear characteristics when machining cast iron, particularly when the
    structure contains some Ferrite.

 

 

 

 

 

    Grooving induction hardened stub axle
    Dr-80 Semi-Finishing Through Hardened Steel Shaft

 

 

 

 

 

David Richards Engineering  2013