Bututu maras kyau da aka yi da ƙarfe guda ɗaya wanda babu wani abu a saman ƙasa ana kiransa bututun ƙarfe mara ƙarfi. Dangane da tsarin samar da bututun, an raba bututun da ba su da kyau zuwa bututu mai zafi, bututu mai sanyi, bututun sanyi, bututun da aka cire, bututun sama, da makamantansu. Dangane da siffar sashin, bututun ƙarfe maras sumul ya kasu kashi biyu: siffar madauwari da siffar da ba ta dace ba, kuma bututun yana da siffar murabba'i, siffar elliptical da makamantansu. Matsakaicin diamita shine 650mm kuma mafi ƙarancin diamita shine 0.3mm. Sumul karfe bututu ne yafi amfani da man fetur geological hakowa bututu, fatattaka bututu for Petrochemical masana'antu, tukunyar jirgi bututu, hali bututu da high-daidaici tsarin karfe bututu ga mota, tarakta da kuma jirgin sama.