Ngobaisikhunta isisekelo, ngokuvamile, uma umumo wokubumba ulula uma kuqhathaniswa, idayi ephansi yefa ngokuvamile isetshenziswa njengendawo yomgodi oyinhloko ukuze kufane imodeli, futhi idiyizi engenhla ngokuvamile ingaba lula noma isebenzise i-anvil eyisicaba. Uma ukwakheka kwe-forging kuyinkimbinkimbi futhi indawo ehlukanisayo isethwe phakathi nendawo, i-cavity idinga ukuklanywa kokubili okungaphezulu kanye nefa eliphansi. Ngokuvamile, phezulu naphansi kuyafa(isisekelo sesikhunta)zisetshenziselwa ukubumba i-forging. Ifa eliphansi ngokuvamile lidlala indima enkulu kanti elingaphezulu liyasiza. Nokho, kukhona izimo ezikhethekile. Uma ukubunjwa kwe-die ephansi kungalungile, i-die engenhla ingasetshenziswa njenge-cavity eyinhloko, ngoba ukwakheka kwe-reverse extrusion kuyoba lula. Okubaluleke kakhulu ukubona ukuma kwe-forging.
