Stack Inserter

Lore & Background

In the quiet hours before the Spiders first skittered across the cracked plains, the player's early factory was a tangle of single-item inserters, each one a tiny mechanical hand doing honest, slow work. The Stack Inserter arrived as the operation grew too large for that kind of patience. Suddenly, a single arm could swallow a full batch of iron plates and vomit them into a furnace in one breath. The rhythm of the factory changed: the staccap tap of one-item transfers gave way to a heavier, more muscular clunk as bulk loads shifted between stations. The aliens never cared about inserters. The Centipede's maw could crush a long-handed arm as easily as a standard one, and the Behemoth's shadow made the entire logistics layer of the factory irrelevant. But for the player, the Stack Inserter was a small, personal victory over the tyranny of single-item throughput — proof that the machine could be made to think in batches, in eighths, in the language of scale that a gigafactory demands. In the broader mythology of the game's world, the inserters are the player's only true allies. The assemblers are dumb, the furnaces are slow, the trains are temperamental. But the inserters never stop, never complain, and never look at the horizon where the alien blight creeps closer. They simply move what they are told to move, eight at a time, until the sky turns the colour of rust.

In Their Own Story

The night shift at the copper-processing annex was quiet in the way that only a fully automated factory can be quiet — a low, omnipresent hum, the occasional clatter of a belt shifting, and the soft hydraulic hiss of two hundred Stack Inserters working in perfect, mindless unison. The player stood at the edge of the catwalk, coffee long gone cold in a tin cup, watching the arms dip and rise. Each one snatched a fistful of refined copper from the smelter's output slot, pivoted on its joint with a faint metallic whisper, and pressed the load into the waiting chest. Eight pieces. Always eight. The motion was so smooth it looked almost organic, like a row of identical hands scooping grain from a bin. Somewhere beyond the floodlights, past the last row of solar panels, the ground trembled with a rhythm that had nothing to do with the factory. The player set the cold cup on the railing and watched the arms keep working. They would keep working long after the lights went out. They always did.

Reader's Guide

The Stack Inserter's sole function is high-throughput item transfer between two adjacent slots — a machine output to a chest, a belt to an assembler input, a chest to a furnace. It has one input slot and one output slot, just like every other inserter, but each transfer cycle moves up to eight items instead of one. At its base speed of 0.5 items/s, a single Stack Inserter can theoretically push four items per second when the source slot is full, making it roughly eight times more efficient than a standard inserter for bulk material movement. It is unlocked by the Stacks technology, found in the Logistics 2 research tree. No special adjacency rules apply beyond standard inserter placement: it must be positioned so its reach overlaps both the source and destination slots. It cannot be placed on a belt tile, and it respects the same collision rules as any other inserter. In practice, Stack Inserters shine in front of fast assemblers, chemical plants, and any station that consumes or produces items in large batches. They pair naturally with fast belts and large storage chests. Because they do not have extended reach, they cannot span the gap that a long-handed inserter covers, so they are best used in tight, dense layouts where machines sit directly adjacent to each other. For filtering specific items, a Filter Inserter is still required; the Stack Inserter will grab whatever is in the slot, up to eight of it, regardless of type.

Did You Know?

• The Stack Inserter is the only inserter variant that can move more than one item per transfer cycle, making it the sole choice for bulk logistics.
• Despite its higher throughput, it retains the same standard reach as a basic inserter, so it cannot bridge the extra tile that a long-handed inserter covers.
• A single Stack Inserter in front of a fast assembler can keep the machine fed at full speed for most recipes, eliminating the need for multiple standard inserters.
• The Stacks technology that unlocks it sits in the Logistics 2 research tree, placing it firmly in the mid-to-late game progression.