Ice does not sharpen garbage disposal blades.
More Info: Considering the question from a technical perspective, ice does not have the physical attributes to sharpen metal nor does a garbage disposal have blades to sharpen. That being said, ice is an inexpensive and effective tool to help clear jams and clean the stationary grinding ring– oftentimes the actual problems that are blamed on ‘dull blades’.
The Anatomy of the Garbage Disposal –No Blades
Many think of the garbage disposal as working like a food processor that chops, grinds, and pulverizes food through the action of spinning blades. Instead, the garbage disposal utilizes a spinning plate called an impeller that mashes food against a stationary grinder ring.
The actual mechanical action of a garbage disposal functions more like a motorized mortar and pestle than a food processor.
How a Food Waste Disposer Works
The garbage disposal works with centrifugal force. When water and food waste enter the grinding chamber, they land on a spinning impeller that continuously pushes the waste into the stationary grind ring on the encasing the interior of the unit. The centrifugal force will pull the grinded waste back to the center of the unit where it will again push it outward toward the grinding ring. It will continue this process until the food waste is small enough to pass through the grinding ring and out to the waste pipe where it will exit the home.
See the video How a Disposer Works from Insinkerator
Some Units Have Additional Cutting Features
Some units have additional cutting components, such as the KitchenAid Superba®, which has an additional undercutter disk®. The disposer functions in the same way as mentioned above, but in this case, there is an additional disk with serrated edges that functions to chop the food waste as well as to grind it against the stationary grinding ring. Though it does ‘cut up’ food waste where most disposers do not, the disk is not a sharp ‘blade’ in the traditional sense such as that used in a food processor.
Ice Is Not an Effective Sharpening Tool
Metal blades that require sharpening are pieces of metal that have been ground down on the edges to form an angle or cutting edge. In order to create a sharp edge, the metal must be removed, which is accomplished by grinding it down against something gritty like a sharpening stone.
Ice does not make an effective sharpening tool.
Ice Is an Effective Tool to Use in a Garbage Disposal
Though technically throwing ice in your food waste disposer is not sharpening any blades, it is an effective maintenance tool. Running ice through the disposer can help to clean any food clogging the interior working parts of the unit and can help to dislodge food particles stuck in the stationary grinding ring.
“How a Disposer Works.” InSinkErator. N.p., n.d. Web. 24 Mar. 2014. <http://www.insinkerator.com/en-us/Household-Products/Garbage-Disposers/Pages/How-a-Disposer-Works.aspx>.
“11. Sharpen a Knife.” Popular Mechanics. N.p., n.d. Web. 26 Mar. 2014. <http://www.popularmechanics.com/home/skills/4223337-11#slide-11>.
“Expert advice from Bob Vila, the most trusted name in home improvement, home remodeling, home repair, and DIY..” Bob Vila Even Your Garbage Disposal Needs TLC Comments. N.p., n.d. Web. 26 Mar. 2014. <http://www.bobvila.com/articles/garbage-disposal-care/#.UzLKm_ldXng>.
“Garbage Disposers and Trash Compactors | KitchenAid.” Garbage Disposers and Trash Compactors | KitchenAid. N.p., n.d. Web. 26 Mar. 2014. <http://www.kitchenaid.com/major-appliances/disposers-and-compactors/>.