Businesses rely on laser printers for professional-looking correspondence, legal documents, reports and marketing materials. A printer that sees a lot of use needs periodic replacement of two items: the toner cartridge and the drum. Understanding what makes these components different helps you maximize printer uptime and minimize maintenance expenses.
Purpose of Cartridge
The cartridge in a laser printer holds toner powder; the printer deposits this finely divided material on the paper, forming text and graphics on the page. Toner is a consumable item, as ink cartridges are for an inkjet printer: the more you print, the more toner the printer uses. When the cartridge runs out of toner, you replace it with a new one. The cartridge has seals that prevent toner dust from getting into the print mechanism and spoiling the output.
Purpose of Drum
A laser printer drum is a metal cylinder with a coating of selenium or other photosensitive material. Inside the printer, a mechanism puts a charge of static electricity on the drum; subsequently, a laser beam scans the drum's surface, removing the static except where it places text. Although you can't see any image on the drum, it exists as a pattern of charge. The static electricity causes toner powder to cling to the drum. The printer rolls a piece of paper against the drum, and the paper receives the toner, producing a page with text.
The capacity of toner cartridges depends on the amount of toner it holds and the type of printing you do; text documents use less toner per page than graphics-heavy marketing materials, for example. A typical cartridge holds enough toner for about 2,000 document pages; high-capacity cartridges for desktop printers are good for about 6,000 pages, and high-output workgroup printers have cartridges that last over 15,000 pages. The drum's lifetime also depends on the type of printer and the documents it produces; color graphics wear a drum out in about 5,000 pages, whereas it can produce 20,000 pages of text. Because you replace drums less frequently than toner cartridges, these are usually two separate maintenance items.
Laser printers use a single drum, but may have more than one toner cartridge. Monochrome models use only black toner, and color laser printers have four cartridges: black, cyan, magenta and yellow. When used in combination, the printer produces all colors, hues and shades of gray. The paper makes four passes on the drum, once for each color. This is why color printing wears the drum out four times as fast as simple text documents.
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