The main task of a paper shredder is to tear a sheet of paper in to tiny bits so that it becomes unreadable. Therefore the machine involves the task of cutting and tearing. These tasks naturally will require a sharp object. The blades of the shredder do this work. One must have noticed that when a knife in the house is used frequently, its sharp edges get worn out after some days. The blades of the shredder are also almost same as the knives. Since they are employed in the task of cutting the papers they may get worn out because of the frictional force developed between the paper and the edges of the blades. The force of friction is the force that is developed between two bodies that are being rubbed. As a result of this force the molecules of the blade change their usual position. Therefore, the molecules in the edge of the blades also change their position. Finally, the sharpness of the blades decreases.
For sharpening the blades of paper shredders, the sole thing required is a kitchen aluminum foil. The kitchen aluminum foil may be of any brand. Tear a part of the foil and keep it near the shredder. Then you may need a pair of scissors in order to cut the foil to a size of 8.5 x 11". You may also fold the foil to the required size. The shredder is then to be plugged in to an electric point. Then turn it to the on' state. The aluminum foil is now to be placed on the top of the shredder. Now, feed the aluminum foil through the shedder. Do it as you feed other normal papers. The aluminum foil works as the sharpening agent. The molecules of the aluminum foil are arranged in such a way that they produce a different kind of frictional force on the rubbing body. As a result the part of the body that comes in direct contact to the foil gets sharpened. The same theory is followed in sharpening the blades of the shredder.
The blades of a shredder must not be sharpened regularly. This will reduce the quality and strength of the blades. The shedder should not be overloaded in order to avoid the worn out of the blades.