Hi

As well the type of the workpeice and the material of the tool, many factors affect on the values of c&n from which are: machining conditions (cutting speed, feed rate, depth of cut). So it is better to determine these values experimentally based on the real machining process you need.......... Good Luck 

Dear Sir. You need to make experimental tests using the ISO 3685 standard. Following the methodology explain in this document you can obtain the C and n values.

See the link below please:

http://www.iso.org/iso/catalogue_detail.htm?csnumber=9151

As reference, if you want, you can use, for example, this paper:

https://www.researchgate.net/publication/269464266_Application_of_ISO_3685_in_the_evaluation_of_the_machinability_of_steel_SAE_1020_during_the_turning_process

Conference Paper Application of ISO 3685 in the evaluation of the machinabili...

 You can use:  n=0.2  & c= 46, but these are an approximated values. It is better to determine n&c experimentally. 

Dear all,

Thank you for your valuable suggestions. I will follow the guidelines.