At what point are the cards scraping?
When you do the Pass the 2 packets should not touch at all until you are squaring them up at the end of the pass.
They do touch, its the tension ( mostly caused by speed without acquiring the knack ) that produces the sound.
The packets touch, since you want to do the move with minimum space. No sound is produced when the knack is acquired ( spelling ), do note that you compensate speed with cover, or sound with more sound.
I advise the original poster to get a proper source for learning the pass. Gary Ouellet's book the Pass is the best for learning the classic pass, but problem with the the classic pass is that you get better with learning more and more about it. This is true for many sleights but particularly true for the classic pass.
Cheers,