Thank you for your reply 

Using a typical dynamometer.

Thank you for your reply 

Also , we can be used load cell or strain gage 

Thank you for your answer, but there are some difficult problem in fixture with milling machine .

i think friction force depended on surface roughness and wear

Thank you Enas , 

I need measuring this force experimentaly 

Dear Enas 

Thank you , but 

What is you  mean "friction force depended on  wear" 

Thank you Gopikrishna_Nidigonda,

but this method for arc welding not friction stir welding 

regards

Dear esraa , 

it is true , the friction stir welding depend on friction and wear at solid state 

regards 

thank you for your reply 

The better method is to use a strain gauge or by using load cells.