Paper shredders cut sensitive documents in a variety of patterns that are designed to minimise the chances of their being put back together. Some are crosscut, while others are diamond or confetti-cut. Regardless of the pattern, shredders have metal blades that cut the paper into shapes. As the blades cut through paper, they create dust that builds up and causes the blades to wear down. Users must clean and maintain the blades to keep the shredder functioning well.
Read the manual that came with the shredder. Some shredders are self-sharpening models. They have sheets of metal that sharpen their blades at every stroke, maintaining the edge. You should keep these models oiled, but there is no need to worry about sharpening them. Eventually, however, the blades will become dull. When this happens, you should remove them according to the manufacturer's instructions and either replace them or have them sharpened by a professional.
Maintain the blades. Oiling the shredder blades will keep them sharp and maximise the time in between blade replacements or professional sharpening. Shredders, whether self-sharpening or not, operate better when they are well-oiled. There are two methods to oil a sharpener. The first is to coat a piece of paper with shredder oil and then feed it through the shredder. The second is to turn the shredder off, put oil along the top of the blades, and then run the shredder in reverse for 10 to 20 seconds. Then, run a few sheets of dry paper through the shredder. Whichever method you choose, the oil will keep the shredder running smoothly and help to clear out the dust that dulls the blades. You will need to oil your sharpener often: about every 30 minutes of shredding time. This means that a shredder that is used heavily needs oil about every four hours of real time, while a shredder under normal use should be oiled every few weeks. The frequency of oiling also depends on the type of shredder. The more cuts that it makes, the more dust is produced, so, for example, crosscut shredders need oil more often than strip-cut. You should only use the shredder oil that is specified by the manufacturer to oil your shredder. Using aerosol oils (such as WD-40) or other non-approved oils can void the warranty on your shredder.
Run aluminium foil through the shredder. If your shredder does not sharpen itself, you can use aluminium foil to replicate the effect that the metal sheet has in self-sharpening models. Use regular kitchen foil and feed two or three sheets into the shredder. This will give dull blades some of their edge back. However, it is not a perfect fix. Some blades may be too dull to be resharpened in this way. If your blades are still fairly sharp, use the aluminium foil method every few weeks to keep them sharp for as long as possible.
Send the blades to be professionally resharpened. Use this method if your self-sharpening blades dull, or if your blades are too dull to be resharpened using the aluminium foil method. Paper shredder manufacturers recommend that users never try to resharpen blades themselves; instead, have a professional sharpener restore their edge.
Replace the blades when necessary. Sharpening is accomplished by removing some of the metal. Eventually, the blades are so worn down that sharpening is ineffective. When this happens, buy replacement blades. Make sure to maintain them well so that they stay sharp for as long as possible.
With the price of shredders so low, it may be more cost-effective to replace the shredder when it no longer shreds properly.