Izikrufu zamagxa ziyinto eqhelekileyo yokudibanisa oomatshini esetyenziswa ngokuqhelekileyo ukudibanisa amacandelo kwaye iqhuba kakuhle ekuthwaleni umthwalo kunye neendawo zokungcangcazela. Yenzelwe ukubonelela ngobude obuchanekileyo kunye nobubanzi bokuxhasa ngokufanelekileyo kunye nokubeka iindawo zokudibanisa.
Intloko ye-screw enjalo idla ngokuba yi-hexagonal okanye intloko ye-cylindrical ukuququzelela ukuqiniswa kunye ne-wrench okanye isixhobo se-torsion. Ngokuxhomekeke kwiimfuno zesicelo kunye neemfuno zezinto eziphathekayo, izikrini zamagxa zihlala zenziwe ngensimbi engenasici, i-alloy steel, okanye i-carbon steel ukuqinisekisa ukuba banamandla okwaneleyo kunye nokuxhathisa ukubola.