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Inserter basics

Inserters are single-tile machines that can take and place items automatically. They are essentially robotic arms with grippers and they operate by swinging back and forth. They can face four directions. Every inserter takes from only the tile in front of it and places only on the tile behind it. The only exception to this is the long-handed inserter, which takes from exactly 2 tiles ahead and places on the tile exactly 2 behind it. Inserters can take from or place into any machine, as well as transport belts and chests, which makes them essential for nearly all automated systems. Most inserters can hold only one item at a time but with technology upgrades the base capacity can reach three items. All inserters work using electricity, with the important exception of burner inserters.

Inserters are particularly useful for moving items between machines and chests. In addition, they are great for moving items on and off of transport belts. When an inserter takes from a transport belt, it prefers the closer lane but it can take from both. When an inserter places onto a transport belt, it can only place onto the further lane, even if the nearby line is empty.

Note that slower inserters are sometimes not fast enough to catch items that are moving on faster transport belts, or items going around corners. Generally, burner inserters are too slow for faster belts, regular inserters are good in most cases, and fast inserters can catch up with any belts.

Inserter logic

Usually an inserter automatically picks up only the items that are relevant to its destination machine. For example, an inserter feeding a lab will only pick up science packs. Furthermore, inserters deliberately stop after placing only a handful of items into their destination machines so that the other items can remain at the source tile (like on a belt or in a chest) so that these items can be used elsewhere. This restriction does not apply to filling and/or emptying chests and/or belts to each other, so that you can do things like emptying a chest completely onto a belt. If there are multiple inserters taking from the same source tile, they will usually take turns in picking up items so that the source is equally shared.

Burner inserter

Burner inserters (grey) use burner fuels to move and they can automatically refuel themselves if they pick up a burner fuel from a belt or a chest while their fuel level is low. Note that they cannot take fuel out of other burner devices to refuel themselves. To quantify their fuel consumption rate, one piece of coal provides enough energy for fifty seven inserter operations. When newly placed, burner inserters begin operating with a tiny amount of free energy inside them. Meanwhile, the problem of having to constantly refuel burner inserters makes it difficult to use them at large scales unless they are moving burner fuels. An ideal place to use them is when feeding coal to boilers or refueling burner mining drills that produce coal. They are the slowest of all inserters and they are not fuel efficient when compared to electrical inserters.

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