An employee was working on an adjacent thermoforming line when he saw a pile of regrind collecting on the top of the regrind system hopper. He climbed up to the platform to access the area where the regrind was collecting. As he brushed away the pile of regrind to try to determine how it was leaking out of the system, his right middle finger entered an access hole in the side of the airlock. The blade inside the airlock amputated his fingertip.