Home / DR-80/85 Applications
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
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.
Turning with CBN
