What is the difference between the toner cartridge and the drum unit? What's the transfer belt unit and waste toner box?

If you own a laser printer, you should definitely be aware of the difference between a toner and a drum unit, to make sure you are buying the correct consumables for your printer.


Most laser printer's drum and toner is one part (Eg HP/Canon), all you need to buy is the toner cartridge. Whereas others is assembled, installed and sold separately (Eg Brother/Samsung), in which case you might be confused about what to buy.


The Brother website explains well the difference. The toner cartridge and drum unit are different consumables. They are used in the Brother machine, and the machine requires both consumables.


What is a toner cartridge?


The toner cartridge contains powder (toner) used for creating letters and images. You need to replace the toner cartridge when the toner is running short or print quality becomes poor because of toner deterioration.



Toner Cartridge TN-450 for Brother Monochrome Printer HL-2240.

Toner Cartridge Pack TN-221/TN-225 for Brother Color Laser Printer HL-3140CW.



What is a drum unit?

The drum unit transfers the toner to the paper. The laser printer puts the toner on the roller called "The photosensitive drum" inside the drum unit, and then prints letters and images by fixing toner to the paper by heat and pressure.

Please be aware that drum unit is also consumables and it has limited page yield, you will need to replace it when your printouts appear excessively blackened, or you get a warning message asking you to replace drum. Usually a drum unit can last 3-4 times longer than the toner.



Drum Unit DR-420 for Brother Monochrome Printer HL-2240.

Drum Unit 

DR-221CL for Brother Color Laser Printer HL-3140CW.


How to assemble the toner and the drum?


The drum clips onto the back of the toner and it holds the toner from outside. Please check the below video as an example on how to assemble or separate the toner and the drum.


How to Install TN-450 Compatible Toner with Printer Brother HL-2240
How to Install TN-221/225 Compatible Toner with Printer Brother HL-3140CW


What is a Belt Unit?

Some color laser-class printers use a rotating belt called a “transfer belt unit” to further color registration accuracy. It is a rotating belt that is typically large which carries the mixture of different colors of toner particles. The cartridges will then precisely apply each toner layer to the belt which will then apply the combined layers uniformly onto the paper. You might need the belt unit to be replaced after some time of use. A belt unit is usually located under the toner and drum.


Belt Unit BU-220CL for Brother Color Laser Printer HL-3140CW.

What is a waste toner box?

A waste toner box collects waste powder. Any powder that is left over from the print process is collected into the box. Once the waste toner box is

full, the printer will stop working until you have it replaced.


Waste Toner Box Brother WT220CL for Brother Color Laser Printer HL-3140CW.

If you are still not sure which is the correct product you need for your printer, please call our 24 hours customer service team at 1-866-979-7463, chat with us online or send us an E-mail.

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