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Technology ArticleCheap ballpoint pens for school A ballpoint pen , is a modern writing instrument. A ballpoint pen has an internal chamber filled with a viscous ink that is dispensed at the tip during use by the rolling action of a small metal sphere (0.7 mm to 1.2 mm in diameter) of brass, steel or tungsten carbide[1]. The ink dries almost immediately after contact with paper. Inexpensive, reliable and maintenance-free, the ballpoint has replaced the fountain pen as the most popular tool for everyday writing. There are two basic types of ballpoint pen: disposable and refillable. Disposable pens are chiefly made of plastic throughout and discarded when the ink is consumed; refillable pens are metal or plastic and tend to be higher in quality and price. The refill replaces the entire internal ink reservoir and ball point unit rather than actually refilling it with ink, as it takes special high-speed centrifugation to properly fill a ball point reservoir with the viscous ink. The simplest types of ball point pens have a cap to cover the tip when the pen is not in use, while others have a mechanism for retracting the tip. This mechanism is usually controlled by a button at the top and powered by a spring within the pen apparatus, but other possibilities include a pair of buttons, a screw, or a slide. Rollerball pens combine the ballpoint design with the use of liquid ink and flow systems from fountain pens; Space Pens, developed by Fisher in the United States, combine a more viscous than normal ballpoint pen ink with a gas pressurized piston which forces the ink toward the point. This design allows the pen to write even upside down or in zero gravity environments. Other school needs can be found here for great deals schoolsuccessinfo.org Above information is from wikipedia and is freely distributed under the GNU license Also See: All Articles |