Trim edge damaged

Hi, friends...
Today I have small problem faced during my duty, I found our press child part lightly damage from trim edge.
But, last day when tool running no issue observed like this.i have also sample of last lot.
Then what is the reason of trim edge damage. I want to know root cause.i try to solve this problem.

Quality

Good Evening....

I Am working in Automotive company as Quality Engineer. I have 4 years Experience in this field.
I works with Vendor of Tml, Ford and Audi, General Motors.I want to share my knowledge and also need some challenging question for myself improvement. If anyone need help and question about Automotive field Please share with me i will try to solve your problems and improve in knowledge and awareness about core of quality.