JIS (Japanese Industial Standad) Scew Thead Specifications TECNICAL DATA Note: Although these specifications ae based on JIS they also apply to and DIN s. Some comments added by Mayland Metics Coutesy of: copyight 00 mayland metics/osg copoation
Scew Thead - 1 <Exteio featues of idge> (1) Flank : Thead face (excluding cest and oot of pofile) () Cest : The tap suface joining the two sides o flanks of a (3) Root : The bottom suface joining the flanks of two adjacent flanks (4) Angle of : Angle between adjacent flanks measued at the coss section of scew - including the axis of the scew (5) Flank angle : The angle between the individual flank and the pependicula to the axis of the measued in the axial plane (6) itch : The distance fom a point on one to a coesponding point on the next measued paallel to the axis (7) Lead : The distance a scew advances axially in one complete tun (8) Lead angle : Angle fomed by a helix passing a point on a flank Figue 1 Basic designation of (1) (Extenal ) Cest Root adius Extenal Root cleaance Intenal Cest cleaance Angle of alf angle of alf angle of and plane pependicula to the axis of the scew (applies to paallel ) (9) Majo diamete of extenal : Diamete of a vitual cylinde which touches the cest of the extenal (10) Mino diamete of intenal : Diamete of a vitual cylinde which touches the cest of the intenal (11) Mino diamete of extenal : Diamete of a vitual cylinde which touches the oot of the extenal (1) Majo diamete of intenal : Diamete of a vitual cylinde which touches the oot of the intenal (13) itch diamete : On a staight scew, the diamete of an imaginay cylinde whee the width of the and the width of the space s ae equal. (Intenal )Cest itch Extenal oot eight of fundamental tiangle Mino diamete of Intenal D1 Mino diamete of extenal d1 (Intenal ) Root itch diamete d D1 Majo diamete of extenal Thead ovelap 1 d Majo diamete of intenal D Figue Basic designation of () Majo diamete of extenal itch diamete Cest Mino diamete of extenal Flank Thead idge Lead angle Angle of Extenal Thead goove Intenal itch Mino diamete of intenal itch diamete Majo diamete of intenal
Scew Thead - (14) Simple pitch diamete : Diamete of an imaginay cylinde when a goove width, which is detemined by the diection of an axis of scew, equals half of the efeence pitch. Fo many standad taps, the simple pitch diamete equals the pitch diamete. (15) Vitual pitch diamete : Vitual pitch diamete of a with a efeence pitch and efeence flank angle that fit without intefeence and play in the ove the given engagement (16) eight of Thead : Distance between a vitual cylinde that touches a cest of the and a vitual cylinde that touches a oot; detemined by measuing pependicula to the axis of the scew. (17) eight of fundamental tiangle : Right angle distance between a vitual cylinde (including the helix) fomed by extending and intesecting flanks of to the diection of cest and a vitual cylinde fomed by extending and intesecting flanks of to the diection of oot (18) Cest tuncation : The distance measued pependicula to the axis, between the shap cest and the cylinde o cone which bounds the actual oot. (19) Root tuncation : The distance measued pependicula to the axis, between the shap oot and the cylinde o cone which bounds the actual oot. (0) Thead ovelap : Distance measued pependicula to the axis of the scew between the vitual cylinde of the majo diamete of extenal and the vitual cylinde of the mino diamete of intenal, in extenal and intenal which mutually fit in concentic. (1) ecentage of engagement : Ratio of ovelap in poduct against efeence of ovelap () Length of engagement :Length measued in the diection of the axis, when an extenal and intenal ae fit and mutually contact. Usually this length equals the length of intenal and includes the chamfes of both ends of the intenal (3) Theaded potion : Theaded potion of tap that can be effectively used fo scew. The incomplete chamfeed potion is included.
h h Scew Thead - 3 Type Symbol Basic ofile Equation fo Basic Size Metic scew JIS B005 (coase) JIS B007 (fine) M <Types and Applications> 4 1 8 60 Extenal Intenal d o D d o D d1 o D1 =0.86605 1=0.54166 d=d - 0.649519 d1=d - 1.0853 D=d D1=d1 D=d =itch D=Fo intenal Angle of is 60. The Cest is flat, and thee is cleaance at the oot. Extenal and intenal engage well. Lage oot adius and lowe height enable easy scew pocessing and incease scew stength. The Majo diamete of extenal and pitch ae specified by a simple numeical value (most commonly measued in millimetes). Unified scew JIS B006 (coase) JIS B008 (fine) U 4 1 8 60 Extenal Intenal d o D d o D d1 o D1 5.4 = n =0.86605 1=0.54166 d=d - 0.649519 d1=d - 1.0853 D=d D1=d1 D=d The pofile is same as fo metic. Majo diamete of extenal is measued in inches and the numbe idges is epesented by the numbe of idges pe inch. 5.4 = n aallel pipe JIS B00 (F) h 6 6 7.5 7.5 55 Extenal Intenal d o D d o D d1 o D1 =0.960491 1=0.64037 =0.13739 d=d - h d1=d - h D=d D1=d1 D=d ipe mainly fo mechanical coupling. It is specified accoding to JIS and R8. Fo the US method, some s have a 60 angle. Tape pipe JIS B003 R Rc (T) h 7.5 55 7.5 Intenal Extenal =0.96037 1=0.64037 =0.13778 90 ipe mainly fo tighte potion. Tape 1/16 and 55 angle. Fo the US method, some s have a 60 angle Note: JIS T = BST JIS F = BSF 16 1
Scew Thead - 4 <Toleance> The following ae the equiements fo pope extenal and intenal engagement: 1. Extenal and intenal must have sufficient contact at the flank. Extenal and intenal must have enough engagement. [SAME AS ABOVE!] In ode to meet these equiements, JIS uses classes to define the limits of size and toleance fo the majo and mino diamete of intenal, pitch diamete, and the majo and mino diamete of extenal. Toleance Class The eason fo setting toleance in is: 1. The ensue compatibility. Limit the quality within a given ange Factos that effect the quality of scew include: 1. mateial: type, heat pocessing, suface pocessing, unifomity, etc.... shape: oot adius, incomplete, oundness, suface oughness, concentation of stess 3. detentions: majo diamete, pitch diamete, and mino diamete. Toleance class of idge is pimaily detemined by dimensions. Table 3 Types Name oup Class Fist Second Thid Metic scew (M) Extenal Intenal JIS 4h 6g 8g 4, 5 5, 6 7 Unified scew Extenal JIS 3A A 1A (U) Intenal JIS 3B B 1B Whitwoth scew (W) Second Thid Fouth Use Confoming engagement Clamping geneal machine eneal sevice fo geneal machine Regula bolt
Scew Thead - 5 Angle Eo The diffeence between the actual angle of and the pescibed angle of. Angles lage than the pescibed angel ae " plus", while angles smalle than the pescibed angle ae "minus". It doubles half angle eo. Flank angle eo : Diffeence between the actual flank angle and pescibed flank angle alf angle eo of : Flank angle eo at point whee pofile is symmetical to the cente line of the idge. Figue 3 Angle Eo Examples Inclination Flank angle eo Angle eo of itch Eo escibed idge alf angle eo of alf angle eo of Axis of scew The diffeence between the actual pitch and the pescibed pitch. itch that is lage than the pescibed pitch is " plus", while pitch that is smalle than the pescibed pitch is "minus". eneally this is fo one pitch, but some is fo two pitches. itch eo includes: Simple pitch eo : itch eo fo one pitch Cumulative pitch eo : Total pitch eo between idges which mutually depat two pitches o moe. ogessive pitch eo : itch eo that simple pitch eo is positive o negative eiodical pitch eo : itch eo that simple pitch peiodically inceases and deceases. Figue 4 itch eo examples Refeence pitch Refeence pitch fo thee idges eiodical pitch eo (Fo one peiod) eiodical pitch eo (Fo two peiods) Simple pitch eo Cumulative pitch eo Measued scew
Scew Thead - 6 < and Fome JIS fo ipe Thead> In 198 the JIS fo pipe s was evised and T and F which wee pescibed by that time, have been in the Appendix. R and ae included in the main body of the standad. Fo taps, as in the case with pipe s, T S and F have been in the Appendix. Rc, Rp, and ae in the main body of the standad. Compatibility between a tap, die, and gauge of each scew ae shown in the following table. Table 4 oup Types Symbol Compatibility Refeence Tap aallel intenal Tape intenal aallel intenal fo mechanical coupling Rc Rp Compatible using second class tap fo T - shot o long type Compatible using second class tap fo S Compatible using second class tap fo S ecision of scew can be compatible, but thee is a diffeence in the shape of the tap. Tape extenal R Compatible using die fo T Die aallel extenal fo mechanical coupling Compatible using die fo F Tape extenal R T incompatible auge aallel intenal Tape intenal aallel intenal fo mechanical coupling Rp Rc S incompatible (Judged by tapeed plug) T incompatible F incompatible Diffeent gauge pecision and shape aallel intenal fo mechanical coupling F incompatible Note: JIS T = BST JIS F = BSF copyight 00 mayland metics/osg copoation