The Arc Furnace melts ore with electricity instead of fire. You need neither fuel nor pressure inside, and there is no window of temperature and pressure to hit. Ore in, start, ingot out. In exchange it only handles the basic metals – and the gas from the ore does not stay in the furnace but goes into your room.
At a glance
The key numbers: 5 W base draw, two slots, a chute input and output, separate ports for power and data. The Import slot takes anything that fits an ore slot, the Export slot only ingots. It has no pipe connections.
What it smelts
According to the game data these fixed values apply per ingot:
| Result | from | Time | Energy |
|---|---|---|---|
| Ingot (Iron) | Ore (Iron) | 1 s | 200 J |
| Ingot (Copper) | Ore (Copper) | 3 s | 500 J |
| Ingot (Silicon) | Ore (Silicon) | 3 s | 100 J |
| Ingot (Lead) | Ore (Lead) | 5 s | 1,000 J |
| Ingot (Nickel) | Ore (Nickel) | 5 s | 1,000 J |
| Ingot (Silver) | Ore (Silver) | 5 s | 1,000 J |
| Ingot (Gold) | Ore (Gold) | 6 s | 2,000 J |
| Charcoal | Biomass | 1 s | 500 J |
Charcoal from biomass is the only way to get carbon without firing up the gas furnace.
Worked example
A full stack of 50 iron ore takes 50 · 1 s = 50 s by the recipe values and needs 50 · 200 J = 10,000 J. The same stack of gold ore needs 300 s and 100,000 J. For comparison: a small battery cell stores 36,000 J. For gold a proper power grid pays off.
How a stack runs
- A stack of ore goes into the import slot, by hand or by chute.
- You start it with
Activate– with the button or by chip. By chip this only works whileOnis 1. - The furnace melts the stack piece by piece. Before each piece it checks whether the grid can still supply the energy for it. If not, it switches itself off.
- When the stack is done, it sets
Activateto 0 and outputs the ingots as one stack. - For the next stack you have to start it again.
Where the ore gas goes
The arc furnace has no gas output. The gas an ore releases while melting ends up in the air around the furnace. For 50 iron ore that is 25 mol of Carbon Dioxide and 100 mol of Pollutant – in a small room more than enough to spoil the breathing air. So put it in a room with ventilation or filtering, not in your living module.
For each piece melted it gives off twenty times the recipe energy as heat into the air, 4,000 J for iron, 40,000 J for gold – each time with a spark. Flammable gas such as Methane or Hydrogen has no business near it.
What it cannot do
- No alloys. Steel, solder, invar, electrum and constantan need the Furnace or the Advanced Furnace.
- No cobalt and no uranium. There is no arc furnace recipe for either.
- No ice. Ice does fit into the slot, but it does not become ingots: it melts piece by piece and its gas goes into the room. Gas from ice comes out of the Ice Crusher.
- No dirty ore. Dirty Ore vanishes here without giving off anything. It belongs in the centrifuge.
- No re-melting of ingots. Ingots do not fit into the import slot.
For alloys the arc furnace is still useful: an iron ingot contains exactly 1 iron but no gas. If you melt steel in the gas furnace from ingots instead of ore, there is far less exhaust. How that works is in Making steel: step by step in the furnace.
Building and feeding it
The kit Kit (Arc Furnace) comes from the autolathe: iron 20, copper 5, 60 s, 6,000 J. Placing it is a single step; to take it down you need the hand drill.
The easiest way to feed it is with chutes: ore arrives at the chute input, ingots leave at the chute output into storage. Since every stack has to be started on its own, a chip is best for the job. Behind a Deep Miner with a centrifuge this becomes a fully automatic ingot line.
Controlling it with IC10
The arc furnace knows On, Activate, Lock, readable Idle, RecipeHash, Reagents, ImportCount, ExportCount and the power values. The example switches it on and starts it as soon as something lies in the import slot, and shows ExportCount on a LED Display (Small):
# Arc furnace starts every stack by itself
define ARC -247344692 # Arc Furnace (StructureArcFurnace)
define LED -815193061 # LED Display Small (StructureConsoleLED5)
define NARC HASH("Arc Furnace") # name of the furnace
define NLED HASH("Ingot Counter") # name of the display
define SLOT 0 # slot 0 = Import
alias occupied r0
alias count r1
start:
yield
lbns occupied ARC NARC SLOT Occupied 0
bnan occupied start # no furnace with this name
sbn ARC NARC On occupied # ore present: on, else off
sbn ARC NARC Activate occupied # ore present: start the stack
lbn count ARC NARC ExportCount 0
bnan count start
sbn LED NLED Setting count
j startlbns reads a value from a slot – here Occupied from slot 0. The order matters: the furnace only accepts Activate while it is switched on, which is why On comes first. If it has switched itself off for lack of power, the chip switches it back on in the next tick – so plan enough power. More about slots in the academy under slots.
Arc furnace or gas furnace?
| Arc furnace | Furnace | |
|---|---|---|
| Energy | electricity per ingot | fuel inside the furnace |
| Window of temperature and pressure | none | per recipe |
| Alloys | no | yes |
| Ore gas | goes into the room | stays in the furnace, gas outlet needed |
| Power port | yes | no, data only |
For a start and for large amounts of basic metal the arc furnace is the simpler choice. Once you need steel, the gas furnace joins in.
Common mistakes
- Nothing happens: no power,
Onis 0 or nobody pressedActivate. The furnace needs a grid that can deliver the energy per ingot. - Ingots first, then standstill: after every stack
Activateis back at 0. Start again or let a chip do it. - No ingot comes out: check whether there is a recipe for the ore at all – there is none for cobalt or uranium.
- The air in the room goes bad: that is the ore gas. Ventilate or filter.
- Export slot full: the chute behind it is blocked or missing.
Further reading
- All furnaces and windows: Furnaces and alloys
- Planning power properly: Power grid basics and Power calculator
- Working out alloys: Furnace calculator