It goes through two additional steps: burning out the plastic and then putting the part into a furnace to get the metal particles to "fuse" together more closel

It goes through two additional steps: burning out the plastic and then putting the part into a furnace to get the metal particles to "fuse" together more closely, aka sintering. The printing part just forms a "green" part, it's basically like you would make pottery, the actual strengthening of the part happens in a high-temperature furnace.