This technology is relatively inexpensive, but can result in smudging when used with freshly printed sheets. Friction feeders also wear out with use, making them less practical for use in a high-volume production setting. Vacuum, or air suction, feeders use air to pull paper into the folder. These feeders are much more effective in handling coated, glossy papers, and can be used quite effectively with newly printed papers. However, vacuum feeders tend to be quite expensive, and are generally only available on high-volume machines.
Most machines can fold several sheets of paper together at one time.
However, feeders usually have trouble handling stapled sheets. This means that you may need to feed stapled sheets through the folders by hand. Features Letter folders are fairly straightforward pieces of equipment. However, there are some features to look for that can help process mailings even more effectively. A batch counter prevents the machine from folding more sheets than desired.