Brother MFC-8640D - Manual (Page 15)

USING THE MACHINE AS A PRINTER 1 - 8
6
After the printed page comes out of the machine, put in the next
sheet of paper as in Step 4 above. Repeat for each page that
you want to print.
7
When you have finished the print job, close the back output tray.
Caution
Remove each sheet immediately after printing. If you allow the
sheets to stack, you may cause the machine to jam or curl the paper.