A suction cup is a device made from rubber or plastic and has the shape of half of sphere. Suction cups can not be used on their own-they are usually used with other items such as signs, posters, hooks and calendars.
Since they are malleable in nature, they easily adhere to glass and metal. It's good to note that these units do not adhere to wood or brick without you sand flat or coat them.
How they work
The face of the cup is made of an elastic, flexible material that has a curved surface. When you press the center of the cup against a flat, non-porous surface, you reduce the volume between the suction cup and the flat surface. This causes air or water between the cup and the surface to get out leaving a cavity.
This cavity has no air or water which brings about pressure difference between the atmosphere and the outside of the cup. The pressure difference is what keeps the cup adhered to the surface.
When using the suction cup you need to note that it can not stick to the surface forever. The length of time it takes the cup to return to its original shape depends on the time the water or air takes to get between the cup and surface so equalizing the pressure with the surrounding atmosphere.
The length of time it takes depends on the flatness and porosity of the surface and the quality of the cup's rim. If the quality is high, it will take long for the water or air to fill the cavity.
The suction cup has a number of applications. Some of the most common applications are:
· Affixing items on nonporous vertical surfaces such as tiles walls and refrigerator doors
· In toys where they are used as Nerf darts
· In moving large objects such as raised floor tiles, glass and car windscreens
· Climbing where they are used in climbing tall buildings with smooth exterior surfaces
· In toilet plungers
Guide to buying the cups
For you to buy the right cups for your applications you need to consider a number of factors such as:
Size : the size solely depends on the object that you want to attach or move. For example, if you want to move a car windscreen you should go for a large suction cup. On the other hand if you want to hang a calendar, you should go for a small cup.
Store : there are many stores that sell suction cups, but no two stores are the same. You should do research and identify reputable stores in your area. You should note that there are some business people who will try selling you poor quality cups that are not flexible or elastic enough.