I.Okwu mmalite:
Ngwaahịa ahụ nwere isi ihe nlele na nkọwa nha iri dị iche iche nke etiti etiti, dabara adaba (0.1 ~ 0.58) mm ọkpụrụkpụ nke ihe nlele, ngụkọta nke nkọwa 10, nke nwere efere etiti dị iche iche, nwere ike ime mgbanwe na nha nha dị iche iche. A na-eji ya eme ihe n'ụdị akwụkwọ, nkwakọ ngwaahịa na nlekọta ngwaahịa na ụlọ ọrụ nyocha na ngalaba. Ọ bụ ngwá ọrụ pụrụ iche maka ịnwale ike mkpakọ mgbanaka nke akwụkwọ na kaadiboodu.
u No.1 0.100-0.140 mm
u No.2 0.141-0.170 mm
u No.3 0.171-0.200 mm
u No.4 0.201-0.230 mm
u No.5 0.231-0.280 mm
u No.6 0.281-0.320 mm
u No.7 0.321-0.370 mm
u No.8 0.371-0.420 mm
u No.9 0.421-0.500 mm
u No.10 0.501-0.580 mm