An employee was manually disassembling a sifter system on the second floor, under a bag dump station that was above a blender that mixed dry food ingredients to be packaged. He disengaged three of the four clamps and was trying to disengage the fourth with his left hand; his right hand was caught under the sifter housing when it tilted, resulting in amputation of the ring fingertip and a laceration on the middle finger. The machine was de-energized and isolated at the time.