Roll pass design ( Number of passes required in Rolling)

When we talk, how many passes required in rolling then we calculate Number of passes 

 Number of passes = log of coefficient of Elongation / log(1.29)

Where 

1:- Number of passes can be 6 , 9 , 15 , 19 , 21, 24, etc according Billet Size and Finished Size 

2:- co-efficient of Elongation = Billet Area / Finished Size Area 

https://svinaykumar1987.blogspot.com/2021/09/section-areas-in-rolling-mill.html

3:- log(1.29)= 0.1105897103

Example:- Billet Size- 150×150 mm

                  Billet Area- 22500

                  Finished Size- 20 mm

                  Finished Area- 314 

Co- efficient of Elongation = 22500 / 314 

                                               =71.656051    

Number of passes = log(71.656051) / log(1.29)= 16.77243

                = 16 passes