A Case Study on Effect of Feed Rate on Machinability of Austempered Ductile Iron

Abstract:

Austempered Ductile Iron (ADI) is a type of nodular, ductile cast iron subjected to heat treatments - austenitising and austempering. Whilst machining is conducted prior to heat treatment and offers no significant difficulty, machining post heat treatment is demanding and often avoided. Phase transformation of retained austenite to martensite leading to poor machinability characteristics is a common problem experienced during machining. This case study explains the effect of feed rate on machinability of ADI using cutting force analysis and tool failure analysis. The experimental design consists of conducting drilling trials on grade 1200 and 1400 at constant depth of cut, 25mm; constant speed, 45m/min; no coolant and variable feed rates from 0.2 to 0.35 mm/rev (increment of 0.025mm/rev). Metallography and X-ray diffraction technique was carried out in order to identify and quantify the microstructural phases before and after drilling. The results from the trial infer that the best way to machine ADI efficiently without tool failure is using low feeds and high speeds and without coolant.

• Periodical: Advanced Materials Research (Volume 748)
• Pages: 247-251
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.748.247
• Online since: August 2013
• Authors: Ashwin Polishetty, Guy Littlefair, Tim Pasang
• Keywords: ADI, Feed Rate, Machinability, Tool Failure

References

[1] J. R. Keough and K. L. Hayrynen, Austempered Ductile Iron- The State of the Industry in 2003, presented at the World ADI Conference, Louisville, Kentucky, (2003).

[2] K. L Hayrynen, K. R Brandenberg, and J. R. Keough, Application of Austempered Cast irons, AFS Transactions, vol. 02-084, p.10, (2002).

[3] G. Littlefair, Evaluating Cutting Fluid Machinability Performance, in 3rd International conference on Machining & Grinding, Cincinatti, Ohio, 1999, p.9.

[4] A. Polishetty, T. Wilson, and G. Littlefair, Characterisation of the machinability of austempered ductile iron using drilling, in NZ Metals 2008, Auckland, New Zealand, (2008).

[5] K. R Brandenberg. (2001, May 2002) Machining Austempered Ductile Iron (ADI). Manufacturing Engineering.

[6] M. Goldberg, G. T. Smith, J. T Berry, and G. Littlefair, Machinability Assessment and Surface Integrity Characteristics of Austempered Ductile Iron (ADI) Using Ultra-Hard Cutting Tools, in 3rd International Conference on Machining & Grinding, Cincinati, Ohio, (1999).

[7] M. Goldberg, Machinability research into the mechanics and surface integrity characteristics of Austempered Ductile Iron, PhD Thesis, Faculty of Technology, Southampton Institute, Southampton, (2002).