CE V S PHG 250 0910 Cop yright 2010 b y Wur th 12 0008 PREV AILIN G T ORQUE the t o r q ue r e quir ed t o run a nut do wn a thr ead on cer tain types of nuts designed t o r esis t vibr ation loosening the r esis tance can be pr o vided b y a plas tic inser t or a noncir cular head PR OPERT Y CL ASS A designation sy s t em which de nes the s t r ength of a bolt or nut F or metric fas teners pr oper ty classes ar e designated b y numbers wher e incr easing numbers gener ally r epr esent incr easing tensile s t r engths R OLL THREADIN G F o rming thr eads on a fas tener b y pushing or r olling dies agains t the fas tener without an y r emo v al of metal r oll thr ead in as opposed t o cut thr eading har dens the material making the thr eads s t r onger S AE Stands for Society of Aut omo tiv e Engineers SEMS A scr e w and w asher assembly A scr e w or bolt which has a captiv e w asher the w asher is fr equently loose on the plain shank of the fas tener the shank diameter being equal t o the e ectiv e diameter of the thr ead the thr ead being r olled fr om this diameter SET SCREW A set scr e w is a thr eaded fas tener that is typically used t o hold a slee v e collar or gear on a shaf t t o pr e v ent r elativ e mo tion It is a thr eaded member that normally does no t hav e a head Unlik e mos t o t her thr eaded fas teners it is basically a compr ession de vice normally used t o gener ate axial thrus t SHANK That por tion of a bolt betw een the head and the thr eaded por tion SHEAR STREN GTH Measur ed b y the push or pull agains t the side of a fas tener until the fas tener br eak s for e x ample mo ving an object continually agains t the side of a scr e w that is pr o t ruding fr om a w all As a rule of thumb shear s t r ength is tw othir ds of tensile s t r ength SOC KET HEAD C AP SCREW A scr e w with a r ound head with usually a he x agon indentation in the head for tightening purposes Used on machine par ts and is typically made fr om high s t r ength s t eel STUD A fas tener which is thr eaded at bo th ends with an unthr eaded shank in betw een One end which of ten has a thr ead t oler ance which r esults in mor e thr ead inter fer ence is secur ed int o a tapped hole the o t her is used with a nut T AP B O L T F ully thr eaded bolt TENSILE STREN GTH A common measur e t o compar e the s t r ength of a fas tener It is the load needed t o pull the fas tener apar t TENSION W ASHERS A gener al name giv en t o spring w ashers cur v ed w ashers and disc springs THREADL OC KER Can be a term used for a number of vibr ation r esis tant pr oducts but is no w usually r eser v ed for thr eadlocking adhesiv es Speci cally a liquid anaer obic adhesiv e applied t o nut or but thr ead once har dened it lls the inner spaces betw een the thr eads t o pr oduce a solid plas tic of a kno wn shear s t r ength UNC Stands for Uni ed N ational Coarse UNF Stands for Uni ed N ational F ine W ASHER F A CE A cir cular rim on the underside of the head of a bolt or on one side of a nut with the purpose of pr o viding a at bearing sur face YIELD The r esis tance t o a load pulling on the middle of a fas tener until the fas tener sho w s permanent deformation YIELD STREN GTH The amount of pr essur e r equir ed t o cause permanent deformity ZINC ELECTR OPL A TIN G Zinc electr oplating is a common w a y t o pr o t ect thr eaded fas teners fr om the e ects of corr osion 188 300 series s t ainless s t eel having appr o ximately no t e x actly 18 chr omium and 8 nick el T e rm 188 is used inter changeably t o char acterize fas teners made of 302 302HQ 303 304 305 384 XM7 and o t her v ariables of these gr ades with close chemical compositions ther e is little o v er all di er ence in corr osion r esis tance among the 188 types but slight di er ences in chemical composition do mak e cer tain gr ades mor e r esis tant than o t hers agains t par ticular chemicals or atmospher es 188 has superior corr osion r esis tance t o 400 series s t ainless is gener ally nonmagnetic and is har denable only b y cold w o rking GLOS SAR Y OF TE R M S