Finish turning of Ductile iron with PCBN 05:33

Grey cast iron and ductile (nodular) cast iron are the two main types of cast iron used in today’s industry. The main difference is how the graphite appears. In grey cast iron, the graphite is in the form of flakes, while in ductile iron, the graphite is in the form of nodules. The composition is basically the same, but the demand for purity requires the Sulphur content to be very low in nodular iron.

Grey cast iron

Nodular cast iron

Both grey cast iron and ductile cast iron are very abrasive materials, but ductile iron is regarded as the more difficult one to machine. Ductile iron components can be various housings, shafts and other components mainly for the automotive segment.

Differential case, Gearbox house and Cam-shaft

Generally ductile iron is machined with carbide inserts, both roughing and finishing but when there are high requirements on dimensional tolerances and surface finish, PCBN can be an alternative for the finishing tool. The higher wear resistance of PCBN allows for longer tool life with maintained edge quality, resulting in superior tolerances and surface finish.

Roughing is best done with a hard and wear resistant carbide. Seco’s range of turning grades include TK1001, mainly recommended for grey cast iron, and TK2001, mainly recommended for ductile iron.

For finishing, Seco’s CBN150C is the preferred grade. Grade CBN150C combines the optimum balance between substrate, coating and edge preparation for successful finish machining of high quality ductile iron components.

Depth of cut should be kept as low as possible, 0.1-0.3 mm. Cutting data is similar for carbide and PCBN, about 300 m/min, and feed rates will in finishing depend on surface finish requirement, but is in the range of 0.1 – 0.3 mm/rev. Wiper technology will allows for higher feed rates while maintaining surface finish.



Roughing with Seco's carbide grade TK2001



Finishing with Seco's PCBN grade CBN150C

For more information, please contact your local Seco representative, or our PCBN team:

 

 

Author: Henrik Sandqvist Product Specialist SECOMAX PCBN/PCD SECO TOOLS Shanghai CO., Ltd. Level 2, Building 8, 456 HongCao Rd., Shanghai 200233, China Office: +86 21 5426 5849 Mobile: +86 186 167 90063 e-mail: henrik.sandqvist@secotools.com

Product Manager: Anders Wickman Product Manager SECOMAX PCBN/PCD SECO TOOLS AB 737 82 Fagersta, Sweden Office +4622340254 Mobile +46703431200 e-mail:anders.wickman@secotools.com