Stainless steel milling

Material Classification: P5.x

Material Classification: M1.x, M2.x and M3.x

Main issues

• The dominant wear criteria when milling austenitic and duplex stainless steels are: chipping on the edges due to thermal cracks, notch wear and built-up edge/smearing.
• On the component, burr formation and surface finish problems are the main issues.
  

Suitable cutters and inserts

• Most CoroMill cutters can be used in austenitic and duplex stainless steel simply by choosing a dedicated insert geometry and grade.
• In face milling, CoroMill 245 and CoroMill 300 are more suitable than CoroMill 345 and CoroMill 200, due to the more positive cutter geometry.
• Use cutters with round inserts or small lead angles to minimize notch wear.
• Use positive insert geometries (-ML, -WL).
• GC2030 (PVD) is the first choice.
• GC2040 (MT-CVD) is the complementary grade for tough conditions and cast stainless steel, where abrasive wear dominates.
• GC1030 (PVD) is the universal choice for mixed production (ISO P, M and S)
• If thermal cracks appear, change to a harder/more wear resistant grade, i.e. from GC2040 to GC2030.
• For CoroMill Plura, grade GC1630 is the basic choice and GC1640 is a complementary choice if there is increased demand for toughness and an internal cutting fluid supply is needed.
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Roughing

• Use high cutting speeds (v_c = 492-820 ft/min) to avoid built-up edge.
• In roughing, always run dry, without cutting fluid, to minimize problems with thermal cracks.
  

Finishing

• In finishing, cutting fluid, or preferably mist coolant/minimal lubrication, is
  sometimes necessary to improve the surface finish. There are fewer problems with thermal cracks in finish milling, because the heat generated in the cutting zone is lower.
• With a cermet grade, CT530, sufficient surface finish can be obtained without cutting fluid.
• A feed, f_z, that is too low can cause higher insert wear because the edge is cutting in the deformation hardened zone.

CoroMill^® indexable insert cutters​