Glossary of Screw Terms (JIS B 0101:2013)
2026/05/07
[Scope of Application]
This standard specifies the terminology and definitions related to the "basic principles of screws" and "fastening components (screws, washers, pins, and rivets)" commonly used.
Table of Contents
a) Basics of Screws
1) General
| Number | Term | Definition | Corresponding English (for reference) |
|---|---|---|---|
| 1101 | Screw | The entire cylindrical or conical body with screw threads. | screw thread |
| 1102 | Male screw | A screw in which the threads are located on the outer surface of a cylinder or cone. | external thread, bolt thread |
| 1103 | Internal thread | A screw with threads on the inner surface of a cylinder or cone. | internal thread, nut thread |
| 1104 | Parallel thread | A screw with threads on the outer or inner surface of a cylinder. | cylindrical screw thread, straight thread, parallel thread |
| 1105 | Tapered screw | A screw thread in which the threads are located on the outer or inner surface of a cone. | taper screw thread, taper thread |
| 1106 | Single-start screw | A screw thread where the lead is equal to the pitch. | single-start thread |
| 1107 | Double-start thread | A screw whose lead is equal to twice the pitch. | two-start thread double-start thread |
| 1108 | Multi-start screw | A screw whose lead is equal to an integer multiple of the pitch (at least two times the pitch). | multi-start thread |
| 1109 | Right-hand thread | A thread that, when viewed along the axis, moves forward when turned clockwise (to the right). | right-hand thread |
| 1110 | Left-hand thread | A screw that advances when turned counterclockwise (to the left) when viewed along the axis. | left-hand thread |
2) Basics
| Number | Term | Definition | Corresponding English (for reference) |
|---|---|---|---|
| 1201 | Helical winding | The path traced by a point moving along the surface of a cylinder or cone such that the ratio of axial displacement to the angle of rotation about the axis remains constant. | helix |
| 1202 | Thread | The solid portion between two adjacent threads. | ridge |
| 1203 | Thread groove | The recessed space between two adjacent flanks. | groove |
| 1204 | Reference Profile | The theoretical thread profile of a screw, defined by the theoretical dimensions and angles shared by the female and male threads in a cross-section containing the axis. | basic profile |
| 1205 | Design profile | A thread profile in which the peaks and valleys are rounded or flattened relative to the basic profile. | design profile |
| 1206 | Maximum actual profile | The thread profile that results in the maximum material dimensions when dimensional tolerances are applied to the design profile. | maximum material profile |
| 1207 | Minimum material profile | The screw profile that results in the minimum material dimensions when dimensional tolerances are applied to the design profile. | minimum material profile |
| 1208 | Lead | The distance traveled in the axial direction when making one full revolution around the thread along the helix line. | lead |
| 1209 | Pitch | The distance measured parallel to the axis between two corresponding points on adjacent threads in a cross-section containing the screw axis. | pitch |
| 1210 | Number of threads (per 25.4 mm) | The value obtained by dividing 25.4 mm by the pitch. | threads per inch |
| 1211 | Lead angle | For parallel threads, the angle formed between the helix line of the thread and a plane perpendicular to the axis of the thread passing through a point on the helix.For tapered screws, the angle formed between the generatrix of the tapered surface of the thread and a plane perpendicular to the screw axis passing through a point on the thread, projected onto a plane perpendicular to the radius line of the screw passing through that point. Unless otherwise specified, this refers to the lead angle of the helix on the imaginary cylinder or cone used to define the effective diameter. | lead angle |
| 1212 | Screw axis | The axis of the imaginary cylinder or cone used to define the pitch diameter. | axis of pitch diameter, axis of screw thread |
| 1213 | Pitch line | The generatrix of the imaginary cylinder or cone used to define the pitch diameter. | pitch line |
| 1214 | (Male thread) Outer diameter | The diameter of the imaginary cylinder (or cone) tangent to the crests of the external thread. | major diameter of external thread |
| 1215 | Major diameter of external thread | The diameter of an imaginary cylinder (or cone) tangent to the bottom of the thread groove. | minor diameter of external thread |
| 1216 | Diameter of the female thread groove | The diameter of the imaginary cylinder (or cone) touching the bottom of the internal thread groove. | major diameter of internal thread |
| 1217 | (internal) diameter | The diameter of an imaginary cylinder (or cone) tangent to the crest of the external thread. | minor diameter of internal thread |
| 1218 | Effective diameter | The diameter of an imaginary cylinder (or cone) such that the width of the thread groove equals the width of the thread crest. In this case, when the pitch equals the specified pitch, it is equal to the single effective diameter. | pitch diameter |
| 1219 | Nominal diameter | The diameter representing the dimensions of a screw; the standard dimensions of the outer diameter of a male screw and the root diameter of a female screw are used. | nominal diameter, nominal size |
| 1220 | Reference diameter | In tapered screws, the diameter used as a reference for determining the diameter dimensions. | gauge diameter |
| 1221 | Position of the gauge diameter | In a tapered screw, the position of the plane perpendicular to the axis used to define the gauge diameter. | position of gauge plane |
| 1222 | Frank | The surface connecting the crest and the root of the thread. In a cross-sectional view containing the axis, it is generally a straight line. | flank |
| 1223 | Feed-side flank | The flank facing the direction of travel during threading. | leading flank |
| 1224 | Trailing flank | The flank opposite the leading flank. | following flank |
| 1225 | Pressure-side flank | The flank that bears the load directly when the screw is driven in and loaded. | load flank, pressure flank |
| 1226 | Clearance flank | The flank opposite the pressure flank. | clearance flank |
| 1227 | Peak | The surface connecting the flanks on both sides of the thread. | crest |
| 1228 | Valley Bottom | The surface connecting the flanks on both sides of the thread groove. | root |
| 1229 | Flank angle | The angle formed by each flank, measured in a cross-sectional view containing the screw axis, and a line perpendicular to the axis. | flank angle |
| 1230 | Thread angle | The angle formed by two adjacent flanks measured in a cross-sectional view that includes the screw axis. | thread angle, included angle |
| 1231 | Thread height | The distance measured perpendicular to the axis between a line connecting the tops of the threads and a line connecting the bottoms of the threads in a cross-section that includes the axis of the screw. | thread height |
| 1232 | Crested thread height | In a cross-sectional view containing the screw axis, the distance measured perpendicular to the axis between a line connecting the crests of the pointed peaks and a line connecting the crests of the peaks. | crest truncation |
| 1233 | Truncation height at the valley bottom | In a cross-sectional view containing the screw axis, the distance measured perpendicular to the axis between a straight line connecting the bottoms of the pointed valleys and a straight line connecting the valley bottoms. | root truncation |
| 1234 | Pointed triangle | In a cross-sectional view containing the screw axis, a triangle with a base length equal to one pitch, formed by extending two adjacent flanks toward the apex of the peak until they intersect (forming the apex), and extending the line through the point of intersection toward the valley bottom (forming the base). | fundamental triangle |
| 1235 | Height of the pointed peak | The height of the pointed triangle. | fundamental triangle height |
| 1236 | Hook height | In a cross-sectional view containing the axes of a male and female screw that fit together concentrically, the distance measured perpendicular to the axis between the straight line connecting the peaks of the male screw's threads and the straight line connecting the peaks of the female screw's threads. | thread overlap |
| 1237 | Standard thread overlap | The thread overlap in the standard profile. | basic thread overlap |
| 1238 | Overlap ratio | The percentage of the actual thread engagement height relative to the standard thread engagement height. | percentage of thread engagement |
| 1239 | (Male thread) crest clearance | In a cross-sectional view containing the axes of a male and female thread that fit together concentrically, the distance measured perpendicular to the axis between a straight line connecting the bottoms of the female thread’s valleys and a straight line connecting the tops of the male thread’s crests. | major clearance, crest clearance |
| 1240 | (Male thread) Valley clearance | In a cross-sectional view containing the axes of a male and female thread that fit together concentrically, the distance measured perpendicular to the axis between a straight line connecting the crests of the female thread and a straight line connecting the roots of the male thread. | minor clearance, root clearance |
3) Format
| Number | Term | Definition | Corresponding English (for reference) |
|---|---|---|---|
| 1301 | Thread designation | A designation indicating the type, nominal diameter, and pitch of a thread. | nominal designation of thread |
| 1302 | Standard-pitch screw | The most commonly used type of thread, typically characterized by a combination of nominal diameter and pitch. | coarse thread |
| 1303 | Fine-pitch screw | A screw with a smaller pitch-to-nominal diameter ratio compared to a standard thread. | fine pitch thread |
| 1304 | Triangular thread | A general term for screws whose thread profile is close to an equilateral triangle. | triangular screw thread |
| 1305 | Metric screw | A triangular screw with a 60° thread angle, where the dimensions of each part of the screw are based on a 1 mm standard. | metric thread |
| 1306 | Metric standard-pitch screw | A metric thread with a coarse pitch. | metric coarse thread |
| 1307 | Metric fine thread | A metric thread with a finer pitch than a coarse metric thread. | metric fine pitch thread |
| 1308 | Inch thread | A triangular thread with a 60° thread angle, where the dimensions of each part of the thread are based on a 25.4 mm standard. | inch thread |
| 1309 | Unified coarse thread | A coarse-pitch inch thread with the same standard thread profile as a metric thread. | Unified coarse thread, UNC thread |
| 1310 | Unified Fine Thread | A Unified coarse-pitch thread with the same standard profile as a metric thread, but with a finer pitch than the Unified coarse-pitch thread. | Unified fine pitch thread, UNF thread |
| 1311 | Metric trapezoidal thread | A screw with a symmetrical cross-section featuring large cutouts at the peaks and valleys of the threads, with dimensions based on a 1 mm standard and a thread angle of 30°. | metric trapezoidal screw thread |
| 1312 | 29-degree trapezoidal screw | A trapezoidal screw thread with a symmetrical cross-section featuring large cutouts at the peaks and valleys, with dimensions based on a 1 mm standard and a thread angle of 29°. | 29-degree trapezoidal screw thread |
| 1313 | Square screw | A screw with a thread profile that is nearly square. | square thread |
| 1314 | Sawtooth screw | A screw with an asymmetrical cross-sectional shape used when axial force acts in only one direction. | buttress thread |
| 1315 | Round screw | A screw with a trapezoidal profile featuring a large rounding at the crest and valley of the threads. | round thread, knuckle thread |
| 1316 | Miniature screw | A screw with a small nominal diameter and a thread angle of 60°, used in watches, optical equipment, electrical equipment, and measuring instruments. | miniature screw thread |
| 1317 | Bicycle screw | Screws with a 60° thread angle used in bicycles and similar applications. | cycle thread |
| 1318 | Pipe thread | Screws used for connecting pipes, pipe fittings, fluid handling equipment, and similar items. There are parallel threads and tapered threads. | pipe thread |
| 1319 | Parallel pipe thread | A pipe thread primarily intended for mechanical joining. | parallel pipe thread |
| 1320 | Tapered pipe thread | A pipe thread designed primarily for sealing. | taper pipe thread |
| 1321 | American pipe thread | A pipe thread used in the United States. There are types with a 1/16 taper and parallel threads. The thread angle is 60°. | American Standard Pipe Thread |
| 1322 | Wool-lined conduit thread | Threads used to connect conduit. 1) Thick steel conduit thread: A thread used to connect thick steel conduit , with a thread angle of approximately 55°. 2) Thin steel conduit thread: A thread used to connect thin steel conduit , with a thread angle of 80°. | 1) thick steel conduit 2) conduit tube thread |
| 1323 | Light bulb thread | A thread used for the base and socket of a light bulb. A thread in which peaks and valleys of approximately the same size alternate in a continuous pattern. | Electric socket and lamp-base thread |
4) Interlocking
| Number | Term | Definition | Corresponding English (for reference) |
|---|---|---|---|
| 1401 | (Screw) engagement length | The length measured along the axis of the screw where the male and female threads are in contact and engaged with each other. | length of thread engagement |
| 1402 | Standard engagement length | The reference length used to calculate tolerances, regardless of the actual engagement length. | reference length of (thread) engagement |
| 1403 | Pitch error | The difference between the actual pitch and the specified pitch. | pitch deviation, pitch error |
| 1404 | Single-pitch error | Pitch error for a single pitch. | simple pitch error |
| 1405 | Cumulative pitch error | 2 The pitch error relative to the sum of the pitches between peaks separated by two or more pitches. | cumulative pitch deviation, cumulative pitch error |
| 1406 | (Lead) wobble | 1 A pitch error in which the advance of the thread within a single pitch increases or decreases by one pitch per cycle or over several cycles. | drunkenness |
| 1407 | Pitch Tolerance | The tolerance established for single and cumulative pitch errors between any two threads within a specified length of the screw (typically the standard fit length). | pitch tolerance |
| 1408 | (Thread) Angle Error | The difference between the actual angle of a thread and the specified angle of a thread. | angle error |
| 1409 | (Thread) Taper | The angle formed by the centerline of one flank of the thread and a line perpendicular to the axis (or, for tapered screws where the thread is specified to be perpendicular to the tapered surface, a line perpendicular to the tapered surface) in a cross-section containing the screw axis. | － |
| 1410 | Flank angle error | The difference between the actual flank angle and the specified flank angle. | flank angle deviation, flank angle error |
| 1411 | (Flank) Half-angle Deviation | The flank angle (half-angle) error for a screw thread with a reference profile that is a symmetrical cross-sectional shape. | error of half angle |
| 1412 | (Thread) Half-Angle Tolerance | The tolerance specified for the half-angle error of a thread. | tolerance on half angle |
| 1413 | Effective equivalent | A value obtained by converting the pitch error or half-angle error of a thread to the pitch diameter. | pitch diameter equivalent |
| 1414 | Effective diameter | 1) For parallel threads, the diameter of an imaginary cylinder such that the width of the thread groove measured along the axis is equal to half the specified pitch. 2) For tapered threads, the diameter of a cone such that the width of the thread groove measured along the tapered surface is equal to half the specified pitch measured along the tapered surface. | simple pitch diameter, thread groove diameter |
| 1415 | Total effective diameter | The simple pitch diameter plus (or, in the case of threads, minus) the effective equivalent of pitch error and the effective equivalent of half-angle error. | virtual pitch diameter, functional diameter |
b) Fastening components
1) General
| Number | Term | Definition | Corresponding English (for reference) |
|---|---|---|---|
| 2101 | Screw parts | A component that has a threaded portion, such as a bolt or nut. | threaded fastener |
| 2102 | Screw | 1) A general term for parts with threads. 2) When used in contrast to bolts, a general term for parts with external threads that are used without a nut. | 1) threaded fastener 2) screw |
| 2103 | Threaded section | The external or internal threaded portion of a screw component. However, for external threaded components with a cylindrical section, the incomplete threaded section at the boundary between the cylindrical section and the fully threaded section is not included in the threaded section, while the incomplete threaded section at the tip of the screw is included.For fully threaded (non-cylindrical) male threaded parts, the incomplete threaded sections at the shank base and the thread tip are included in the threaded portion. Note that the chamfered section at the thread tip is part of the incomplete threaded section. | threaded portion |
| 2104 | Full thread | A threaded portion in which both the peaks and the valleys have a complete mountain shape. | complete thread |
| 2105 | Incomplete thread | A thread section where the mountain shape is incomplete due to factors such as the chamfering or engagement of the thread-cutting tool. In male threaded parts with a cylindrical section , incomplete threads occur at the boundary between the cylindrical section and the complete thread section, as well as at the thread tip. In fully threaded male parts, they occur at the base of the shank and the thread tip. | thread runout, vanish thread, washout thread, incomplete thread, run-out of thread |
| 2106 | Chamfer | A chamfered section provided at the end of a threaded section to facilitate engagement between a male and female thread. | chamfer |
| 2107 | Head | The head of a threaded fastener. | head |
| 2108 | Shaft | The part of a threaded fastener excluding the head. | shank |
| 2109 | Cylindrical section | The cylindrical section between the head and the threaded portion of a threaded fastener. | body |
| 2110 | Seating Surface | The surface that directly receives the force when a threaded fastener is tightened. However, this excludes the thread root. | bearing surface |
| 2111 | Top surface | The surface of a bolt head or nut that is opposite the bearing surface and does not bear any load. | top face |
| 2112 | Thread tip | The end of the threaded portion of a male threaded component. | end, point |
| 2113 | Rounded section below the neck | The fillet formed at the transition from the head to the shank. | underhead fillet |
| 2114 | (Screw) relief groove | 1) A groove provided at the boundary between the threaded portion and the cylindrical portion of a male threaded part. 2) A groove provided at the base of the head of a fully threaded male part. | thread undercut |
| 2115 | Slotted groove | A groove provided to allow the tip of a screwdriver to be inserted and rotate the threaded part. | slot |
| 2116 | Cross-recess | A cross-shaped recess designed to accommodate the tip of a Phillips screwdriver for turning a screw. | cross recess |
| 2117 | Hexagonal recess | A hexagonal recess designed to allow a hex wrench to be inserted and used to rotate a fastener. | hexagon socket |
| 2118 | Hexalobular socket | A hexalobular-shaped recess provided for inserting a hexalobular-shaped bar wrench to rotate a threaded component. | hexalobular socket |
| 2119 | Square socket | A square-shaped recess provided for inserting a square-shaped bar wrench to rotate a threaded component. | square socket |
| 2120 | Thread length | The length of the threaded portion (2103). | thread length |
| 2121 | Cylindrical section length | The length from the seating surface to the first complete thread. Includes the undercut or relief groove and the incomplete thread section. | body length |
| 2122 | Nominal length | A representative dimension indicating the length of a threaded fastener. For hex bolts, this is the sum of the thread length and the cylindrical length; however, the method of measurement may vary slightly depending on the part. | nominal length |
| 2123 | Grip length | When tightening with a bolt and nut, this is the distance between the seating surfaces of the bolt and nut. For embedded bolts, it corresponds to the thickness of the fastened member in contact with the nut. For flat-head screws, it is the distance between the outer diameter of the countersink in the member and the seating surface of the nut. | grip length |
| 2124 | Head diameter | The diameter of the largest part of a circular head. | head diameter |
| 2125 | Cylinder diameter | The diameter of the cylindrical section. | body diameter |
| 2126 | Head height | For male threaded parts with a flat seating surface, the distance from the top or upper surface of the head to the seating surface. If the seating surface is not flat, the method of measurement varies slightly depending on the shape of the head. | height of head |
| 2127 | Nut height | The distance between the top surface of the nut and the seating surface. | Thickness of nut |
| 2128 | Flat width | The distance between two parallel faces on a threaded fastener where a wrench is applied. | width across flats |
| 2129 | Diagonal distance | The distance between two opposite corners of the section of a threaded part where a wrench is applied. | width across corner |
| 2130 | Chamfer angle | The angle of the chamfer applied to the top surface of a bolt head, the top surface of a nut, the seating surface, or the threaded hole. | angle of chamfer |
| 2131 | Undercut radius | The radius of the rounded section below the head, measured in a cross-sectional view that includes the axis of the screw. | radius under head |
| 2132 | Diameter of the transition circle | The diameter of the circle where the seating surface of the head and the radius under head meet. | fillet transition diameter |
| 2133 | Effective cross-sectional area (of a screw) | The cross-sectional area of a screw used primarily for stress calculations of the screw component, but also used when determining the guaranteed load stress of a nut. | tensile stress area |
| 2134 | Thread Shear Area | The total area of the threads on the male or female screw that are subjected to shear force within the engagement length between the male and female screws. | thread shear area |
2) Head shape
| Number | Term | Definition | Corresponding English (for reference) |
|---|---|---|---|
| 2201 | Hex (head) | Hexagonal head. | hexagon head |
| 2202 | Hexagon head with shoulder | A hexagon head with a washer face on the underside of the head that has a diameter smaller than the width of two hexagon faces. | hexagon head with washer face |
| 2203 | Square (head) | Square head. | square head |
| 2204 | With Set Hole (Head) | Hexagonal or square head with a side hole for threading wire to prevent rotation. | head with hole, drilled head |
| 2205 | Hex head with flange | Hex head with a disc-shaped collar whose diameter is larger than the diagonal distance of the hexagon to increase the contact area of the head. | hexagon head with collar |
| 2206 | Hexagon head with flange | A hexagon head with a conical collar whose diameter is larger than the diagonal distance to increase the contact area of the head. | hexagon head with flange |
| 2207 | Hexalobular head with flange | A hexalobular head with a conical flange whose diameter is larger than the diagonal distance to increase the contact area of the head. | hexalobular head with flange |
| 2208 | 12-point head with flange | A head with a flange shaped as if three hexagons of the same size and on the same axis were shifted by 30 degrees. | 12-point flange head, bihexagonal head |
| 2209 | Toothed flange (head) | A head with notches on the flange-mounted head’s seating surface to act as a retaining mechanism. | serrated toothed flange head |
| 2210 | Slotted (head) | A head with a slot. | slotted head |
| 2211 | Cross-slotted (head) | A head with a cross-shaped recess on the top. | cross recessed head |
| 2212 | Hexagonal recessed head | A head with a hexagonal recess on the top. | hexagon socket head |
| 2213 | Hexalobular socket head | A head with a hexalobular socket on the top. | hexalobular socket head |
| 2214 | Square-Socket Head | A head with a square recess on the top. | square socket head |
| 2215 | Knurled (head) | A head with knurling to make it easier to tighten by hand. | knurled head |
| 2216 | Round (head) | A head shaped like a hemisphere. | round head, cup head |
| 2217 | Round-flat (head) | A flat head with a rounded top. | raised cheese head, fillister head |
| 2218 | Pan (head) | A flat head with rounded corners on the top. There are variations of this in pan-head rivets. | pan head |
| 2219 | Flat (head) | A low-profile cylindrical head. | flat fillister head |
| 2220 | Cheese (head) | A flat head with a slight slope on the sides. | cheese head |
| 2221 | Truss (head) | A head commonly used on small screws; it is lower in height and has a larger outer diameter than a round head. | mushroom head, cup head, truss head |
| 2222 | Bind (Head) | A large-diameter head with a rounded top. Some have a recess on the seating surface. | binding head |
| 2223 | Breja (Head) | Commonly used with Tapping Screws (2413), this head shape is intermediate between a round head and a truss head. | brazier head |
| 2224 | Wafer head | A head with a low-profile round top and a flange. | wafer head |
| 2225 | Plate (head) | A head with a flat top and a conical seat. | countersunk head, flat head |
| 2226 | Round countersunk head | A countersunk head with a rounded top. | raised countersunk head, oval head |
| 2227 | Undercut countersunk head | A countersunk head with the bottom surface cut away to increase the thread length. | undercut countersunk head, undercut flat head |
| 2228 | Undercut Round Countersunk Head | A round countersunk head fastener with the seating surface of the head cut away to increase the thread length. | undercut raised countersunk head, undercut oval head |
| 2229 | Square-head | A head with a square-tapered seating surface. | Countersunk square head |
| 2230 | Small Countersunk Head | A head with a 60° seat angle and an outer diameter smaller than that of the standard countersunk head (2225). | Countersunk trim head |
| 2231 | Trumpet head | A head where the taper (seating surface) of the pan head is curved. | trumpet head |
| 2232 | T (head) | Rectangular head. | T-head, hammer head |
3) Screw tip shape
| Number | Term | Definition | Corresponding English (for reference) |
|---|---|---|---|
| 2301 | Rough End | A screw tip that has not been chamfered and remains in its as-rolled condition. | as-rolled end |
| 2302 | Chamfered end | A screw end where the tip has been cut and the corners have been chamfered to approximately the diameter of the screw groove. | chamfered end |
| 2303 | Rounded tip | A thread tip that has been rounded. | rounded end |
| 2304 | Flat tip | A thread tip that has been chamfered at approximately 45° to create a flat end face. | flat point |
| 2305 | Cylindrical tip | A type with a cylindrical section at the tip of the threaded portion that is equal to half the nominal diameter of the thread. | long dog point |
| 2306 | Half dog point | A type with a cylindrical section at the tip of the threaded portion that is 1/4 the nominal diameter of the thread. | short dog point |
| 2307 | Full taper point | A thread tip tapered into a 90° cone. | cone point |
| 2308 | Pointed tip | 1) A full cone point (2307) with the tip slightly cut off. 2) A screw tip tapered to approximately 25° as specified in JIS B 1125, with threads extending nearly to the tip. | 1) truncated cone point 2) gimlet point |
| 2309 | Cavity Point | A point with a recess in the center of the threaded end face. | cup point |
| 2310 | Pilot tip | A screw with a pilot (a section with a diameter smaller than the thread groove diameter) at the tip to guide insertion along the inner wall of the female thread. | pilot point |
| 2311 | Cutting edge | 1) A screw with a cutting-edge-shaped groove at the tip. 2) A screw with a drill-like section at the tip. | 1) scrape point 2) drill point |
| 2312 | Tapping Screw Tip | 1) Tapping screw point, Type C: A point sharpened to approximately 45°, with threads extending nearly to the tip of the sharpened section. 2) Tapping screw type F: A flat end face with a tapered tip, where the threads extend parallel to the tapered section. 3) Tapping screw type R: A tip tapered to approximately 45°, with a rounded tip, where the threads extend to near the tip of the tapered section. | 1) Tapping screw Type C (cone end) 2) Tapping screw Type F (flat end) 3) Tapping screw Type R (rounded end) |
4) Small screws, etc.
| Number | Term | Definition | Corresponding English (for reference) |
|---|---|---|---|
| 2401 | Small Screw | A screw with a head and a relatively small nominal diameter. Common drive types include slotted and cross-recessed. | machine screw |
| 2402 | Slotted machine screw | A machine screw with a slotted head. | slotted head machine screw |
| 2403 | Slotted machine screws for precision equipment | Slotted head machine screws for use in precision instruments such as optical and measuring equipment. | Slotted head screw for precision instruments |
| 2404 | Small Screw with Cross-Slot | Small screws with a cross-recessed head. | Cross-recessed head machine screw |
| 2405 | Cross-recessed machine screw with built-in washer | A cross-recessed head machine screw with a captive washer to prevent the washer from falling off. | Cross-recessed head screw with captive washer |
| 2406 | Hexalobular-head small screw | Hexalobular socket head screw. | hexalobular socket head screw |
| 2407 | Small Screws for Eyeglass Frames | Small screw for eyeglass frames. | machine screw for spectacle frames |
| 2408 | Screw with built-in flat washer | A small screw or bolt with a flat washer integrated to prevent it from falling off. | screw and washer assembly with plain washer |
| 2409 | Set screw | A screw used to secure the movement of mechanical parts by utilizing the tip of the screw. Common drive configurations include slotted, hex socket, and square head. | set screw |
| 2410 | Slotted set screw | A set screw with a slot. | slotted set screw, slotted grub screw |
| 2411 | Hex socket set screw | Hex socket set screw. | hexagon socket set screw |
| 2412 | Square set screw | Square-head set screw. | square head set screw |
| 2413 | Self-tapping screw | A general term for screws that can create their own threads. Common drive configurations include slotted, cross-recessed, and hex head. | self-tapping screw, tapping screw |
| 2414 | Slotted self-tapping screw | A slotted tapping screw. | slotted head tapping screw |
| 2415 | Cross-recessed tapping screw | Cross-recessed tapping screw. | Cross-recessed head tapping screw |
| 2416 | Hex Tapping Screw | Hex head tapping screw. | hexagon head tapping screw |
| 2417 | Tapping screw with integrated flat washer | Tapping screw with a built-in flat washer to prevent the washer from falling off. | Tapping screw with integrated flat washer |
| 2418 | Hex Tapping Screw with Flange | Hex head tapping screw with flange. | Hexagon washer head tapping screw |
| 2419 | Hexagon flange head tapping screw | Hexagon flange head tapping screw. | Hexagon flange head tapping screw |
| 2420 | Hexalobular-Slot Tapping Screw | Hexalobular socket head tapping screw. | hexalobular socket head tapping screw |
| 2421 | Drilling Tapping Screw | A tapping screw with a pointed tip that does not require a pilot hole. | Self-drilling tapping screw |
| 2422 | Drill screw | A tapping screw with a cutting-edge tip that does not require a pilot hole. | drilling screw |
| 2423 | Thread-rolling screw | A general term for screws that form metric female threads on the mating surface through plastic deformation and tighten the joint. | thread forming screw |
| 2424 | Wood screw | A screw with a tip and threads designed for driving into wood. Common drive configurations include slotted and Phillips heads. | wood screw |
| 2425 | Slotted wood screw | A wood screw with a slotted head. | slotted head wood screw |
| 2426 | Phillips head wood screw | Cross-recessed wood screw. | Cross-recessed head wood screw |
| 2427 | Coach screw | A wood screw that is relatively larger than standard wood screws. | Coach screw |
| 2428 | Drive-in screw | A screw that is driven into the wood like a nail to secure it. | drive screw |
5) Bolt
| Number | Term | Definition | Corresponding English (for reference) |
|---|---|---|---|
| 2501 | Bolt | A general term for threaded fasteners typically used in conjunction with nuts. They are classified into the following four types based on the shape of the shank: 1) Nominal diameter bolts 2) Full-thread bolts 3) Effective diameter bolts 4) Expansion bolts | bolt |
| 2502 | Nominal diameter bolt | A bolt whose cylindrical body diameter is approximately equal to the nominal diameter of the thread. | bolt with nominal diameter body |
| 2503 | Fully threaded bolt | A bolt without a cylindrical body. | － |
| 2504 | Bolt with effective diameter | A bolt whose shank diameter is approximately equal to the effective diameter of the thread. | bolt with reduced shank |
| 2505 | Expansion bolt | A bolt designed to be easily extended by reducing the diameter of part or all of the cylindrical section. | bolt with waisted shank |
| 2506 | Hex bolt | A general term for bolts with a hexagonal head (2201). | hexagon bolt, hexagon head bolt |
| 2507 | Hexagon bolt with built-in washer | A hexagon bolt with a washer integrated to prevent it from falling off the screw. | hexagon head screw with captive washer |
| 2508 | High-Strength Hexagon Bolts for Friction Joints | Hexagon head bolts with high tensile strength used in construction (such as steel-framed buildings) and civil engineering (such as bridges). Generally referred to simply as "high-strength bolts." | hexagon head bolt for high-strength structural bolting |
| 2509 | Square-head bolt | A bolt with a square head. | square head bolt |
| 2510 | Hex bolt with flange | A hex head bolt featuring a conical flange with a diameter larger than the diagonal of the hexagon to increase the contact area of the head. | hexagon flange bolt |
| 2511 | Hexalobe bolt with flange | A hexalobular head bolt featuring a conical flange with a diameter larger than the diagonal distance to increase the contact area of the head. | hexalobular head bolt with flange |
| 2512 | Flat-head bolt | A flat-head bolt, available in types such as slotted and keyed. | flat head bolt |
| 2513 | Hex socket head bolt | Hexagon socket head cap screw. | hexagon socket head cap screw |
| 2514 | Hexagon socket head cap screw | A bolt with a hexagon socket on a round head. | hexagon socket button head screw |
| 2515 | Hexagon socket shoulder bolt | A hexagon socket bolt with a cylindrical shank diameter larger than the nominal thread diameter. | hexagon socket head shoulder screw |
| 2516 | Hex Socket Flat Head Screw | A bolt with a hexagon socket in the countersunk head. | hexagon socket countersunk head screw |
| 2517 | Hexalobular socket head bolt | A bolt with a hexalobular socket head. | hexalobular socket head cap screw |
| 2518 | Square-root round-head bolt | A bolt with a square section at the base of the round head to prevent rotation. | cup square neck bolt, cup head square neck bolt |
| 2519 | Round-head bolt with key | A bolt with a key at the base of the cup head to prevent rotation. | cup head nib bolt, cup nib bolt |
| 2520 | Knurled Cup Head Bolt | A bolt with a knob-shaped protrusion at the base of the cup head to prevent rotation. | cup oval neck bolt, fish bolt |
| 2521 | Hexagonal Reamed Bolt | A hex bolt designed to fit snugly into a reamed hole, serving to prevent slippage. There are types with a parallel cylindrical shank and those with a slight taper. | hexagon fit bolt, hexagon head reamer bolt |
| 2522 | Butterfly bolt | A bolt with a wing-shaped head. | wing bolt |
| 2523 | Eye bolt | A bolt with a ring-shaped head featuring a round hole. The head is fitted with a seat at its base. | eye bolt, eyebolt |
| 2524 | Eyelet bolt | A bolt with a head formed by bending a piece of material into a ring shape, the outer diameter of which is approximately equal to that of the screw. | eyelet bolt |
| 2525 | Hook bolt | A bolt with a hook-shaped head. | clip bolt, hook bolt |
| 2526 | U-bolt | A bolt shaped like the letter "U" with threads on both ends. | stirrup bolt, U-bolt |
| 2527 | Welded bolt | A bolt with a protrusion on the seating surface, designed to be welded to a steel plate. | weld bolt |
| 2528 | Threaded Weld Stud | A rod-shaped bolt with a cylindrical section having a diameter nearly equal to the effective diameter. One end of the cylindrical section is attached to the structure using arc stud welding. | weld stud, single-end stud, threaded stud |
| 2529 | Anchor bolt | A bolt with threads on both ends, used by firmly embedding one end into the body of a machine or similar structure. | stud, stud bolt, tap-end bolt |
| 2530 | Retaining bolt | A bolt that sets the spacing between two plates and acts as a support for them. | stay bolt |
| 2531 | Foundation bolt | A bolt used to secure a mechanical structure to its foundation during installation. | foundation bolt |
| 2532 | T-bolt | A bolt with a T-head (2232). | T-head bolt, hammer head bolt |
| 2533 | T-slot bolt | A bolt designed to fit into a T-slot. | T-slot screw, T-slot bolt |
| 2534 | Upset bolt | A bolt whose head has been formed into a hexagonal or square shape through upsetting. | upset head bolt |
| 2535 | Trimmed bolt | A bolt whose head has been punched into a hexagonal or square shape using a trimmer. | trimmed head bolt |
6) Nut
| Number | Term | Definition | Corresponding English (for reference) |
|---|---|---|---|
| 2601 | Nut | A general term for threaded fasteners. | nut |
| 2602 | Hex nut | A general term for nuts with a hexagonal shape. JIS B 1181 classifies hex nuts into the following five types: 1) Hex nut—Style 1 2) Hex nut—Style 2 3) Hex nut—C 4) Hex thin nut —chamfered 5) Hex thin nut—unchamfered | hexagon nut 1) hexagon nut (style 1) 2) hexagon nut (style 2) 3) hexagon nut 4) hexagon thin nut (chamfered) 5) hexagon thin nut (unchamfered) |
| 2603 | Hexagon Nut with Seat | Hexagon nut with a seating surface diameter slightly smaller than the width of the hexagon. | Washer-faced hexagon nut |
| 2604 | High-strength hex nut for friction-lock fasteners | Hex nut designed to be used with high-strength hex bolts for friction-fit connections. | hexagon nut for high-strength structural bolting |
| 2605 | Square Nut | A nut with a square cross-section. | square nut |
| 2606 | Hex Nut with Flange | A hex nut with a disc-shaped collar whose diameter is larger than the diagonal length of the hexagon to increase the contact area. | hexagon nut with collar |
| 2607 | Hexagon Nut with Integrated Washers | A hex nut with a flat spring washer, wave spring washer, or similar component integrated into the seating surface. The integrated washer can rotate freely relative to the nut and is designed to prevent it from falling out. | hexagon nut and spring washer assembly |
| 2608 | Hexagon Nut with Flange | A hexagon nut featuring a conical flange with a diameter larger than the diagonal of the hexagon to increase the contact area. | hexagon nut with flange |
| 2609 | 12-point nut with flange | A flanged nut shaped as if three hexagons of the same size and axis were shifted by 30 degrees. | 12-point flange nut |
| 2610 | Toothed Flange Hex Nut | A flanged hex nut with notches on the seating surface to act as a backstop. | serrated toothed flange nut, lock face nut |
| 2611 | Cap nut | A nut with one side shaped like a cap to prevent the tip of the external thread from showing. | cap nut, box nut |
| 2612 | Hex box nut | A box nut with a hexagonal shape. | acorn nut, domed cap nut |
| 2613 | Round Nut with Groove | A round nut with a slot on the top. | slotted round nut |
| 2614 | Slotted round nut | A round nut with vertical slots cut into the sides. | slotted round nut for hook-spanner |
| 2615 | Round Nut with Side Hole | A round nut with holes on the side used for tightening the nut. | Round nut with set pin holes in the side |
| 2616 | Round Nut with Top Hole | A round nut with holes on the top surface for tightening. | Round nut with drilled holes on one face |
| 2617 | Eye nut | A nut with a ring attached. | eyenut |
| 2618 | Knob nut | A nut with a thumb knob that allows it to be tightened by hand. | thumb nut |
| 2619 | Butterfly nut | A thumb nut with a butterfly-shaped thumb. | wing nut, fly nut |
| 2620 | Knurled nut | A round nut with a knurled surface. | knurled nut |
| 2621 | Anti-backlash nut | A general term for nuts that have a mechanism incorporated into part of the nut to prevent it from loosening. | self-locking nut |
| 2622 | Spring plate nut | A nut made by punching a sheet of spring steel or similar material. It has only one thread, but the spring action prevents it from turning. | spring nut |
| 2623 | Slotted Hex Nut | A hex nut with a slot for inserting a split pin to prevent the nut from falling off. The following types exist: 1) A hex nut with a slot cut into the top surface. 2) A hex nut with a cylindrical section, with the slot cut into this section. | 1) hexagon slotted nut 2) hexagon castle nut |
| 2624 | Pre-tensioning torque nut | A nut designed with a mechanism that generates the necessary torque when screwing into or unscrewing from a mating threaded part. The following types are available: 1) Prevailing torque type hexagon nut with non-metallic insert 2) All-metal prevailing torque type hexagon nut 3) Prevailing torque type hexagon nut with flange and non-metallic insert 4) All-metal prevailing torque type hexagon nut with flange | 1) Prevailing torque type hexagon nut (with non-metallic insert) 2) Prevailing torque type all-metal hexagon nut 3) Prevailing torque type hexagon nut with flange (with non-metallic insert) 4) Prevailing torque type all-metal hexagon nut with flange |
| 2625 | Plate nut | A nut riveted to a plate for use. | plate nut |
| 2626 | Weld Nut | A nut with a protrusion on its seating surface, designed to be welded to a steel plate. The following three types are specified: 1) Hexagonal weld nut 2) Square weld nut 3) T-shaped weld nut | weld nut 1) hexagon weld nut 2) square weld nut 3) T-shape weld nut |
| 2627 | Hexagonal Weld Nut with Flange | A nut with a protrusion on the flange seat, designed to be welded to a steel plate. | hexagon weld nut with flange |
| 2628 | Nut for eyeglass frames | A nut used for eyeglass frames. | nut for spectacle frames |
| 2629 | T-slot nut | A nut used in a T-slot. | nut for T-slot, T-slot nut |
7) Washer
| Number | Term | Definition | Corresponding English (for reference) |
|---|---|---|---|
| 2701 | Washer | A component inserted between the seating surface of a small screw, bolt, nut, etc., and the fastening part. There are various types depending on shape, function, and application. | washer |
| 2702 | Flat washer | A flat washer. External shapes include rounded or square with a chamfered edge; square ones are specifically called “square washers.” | plain washer |
| 2703 | Spring washer | A coil-shaped washer. Washers come in single-coil and double-coil varieties, and their ends may be flat or claw-shaped. | spring lock washer |
| 2704 | Disc spring washer | A washer with spring action that is dish-shaped. | conical spring washer |
| 2705 | Corrugated spring washer | A washer formed by bending a spring washer (2703) into a wave shape. | wave spring washer |
| 2706 | Toothed Washer | A spring washer equipped with teeth that serve to prevent rotation. | toothed lock washer |
| 2707 | Corrugated washer | A washer formed by bending a round flat washer (2702) into a wave shape. | wave washer |
| 2708 | Tongue Washer | A washer with a protruding section on a round washer, used to prevent rotation. | tab washer, tongued washer |
| 2709 | Flange washer | A washer in which a section of the outer circumference of a round washer is cut open and folded back to act as a retaining tab. | external tab washer, external claw washer |
| 2710 | Internal tab washer | A washer in which two tab-like projections are formed on a portion of the inner circumference of a round washer, and these projections are bent to prevent rotation. | internal tab washer, internal claw washer |
| 2711 | Square Washer with Tabs | A washer with tabs attached to the four corners of a square washer. | square claw washer |
| 2712 | Square taper washer | A square washer with a taper on one side. | square taper washer (for U and I sections) |
8) Pin
| Number | Term | Definition | Corresponding English (for reference) |
|---|---|---|---|
| 2801 | Pin | A rod-shaped or toothed component inserted into a hole for purposes such as joining, positioning, or preventing screws from turning. Some pins have heads. | pin |
| 2802 | Parallel pin | A headless pin with a circular cross-section and cylindrical sides. | parallel pin, straight pin |
| 2803 | Dowel pin | A type of parallel pin that has been heat-treated for high precision. | dowel pin |
| 2804 | Parallel pin with female thread | A parallel pin with an internal thread at one end. | parallel pin with internal thread |
| 2805 | Clevis pin | A pin used for joints. Shapes include those similar to parallel pins, those with split-pin holes, and those with heads; they are commonly used in railway vehicles. | clevis pin |
| 2806 | Tapered pin | A headless pin with a circular cross-section and tapered sides. | taper pin |
| 2807 | Slotted taper pin | A taper pin with a longitudinal split at the smaller end. | taper pin with split |
| 2808 | Threaded Taper Pin | A taper pin with a female or male thread on the larger end. | taper pin with thread |
| 2809 | Spring pin | A pin formed by rolling a flexible strip into a cylindrical shape, creating a spring action in the radial direction of the pin . There are two types: single-coil and double-coil. | spring-type straight pin, spring pin |
| 2810 | Grooved pin | A pin in which a V-shaped groove is cut along the axial direction of a parallel pin, and part of the groove edge is raised. | grooved pin |
| 2811 | Split pin | A component used to prevent screws from loosening or pins from falling out. | split pin, cotter pin |
| 2812 | Snap pin | A pin inserted into a shaft with a hole to prevent it from falling out. | snap pins |
9) Rivets and other fasteners
| Number | Term | Definition | Corresponding English (for reference) |
|---|---|---|---|
| 2901 | Rivet | A component with a head and a shank without threads. The shank is inserted into a hole in the workpiece, and the shank end is crimped to form a joint. | rivet |
| 2902 | Cold-formed rivet | A rivet whose head is formed by cold heading. | cold-headed rivet |
| 2903 | Hot-formed rivet | A rivet with a head formed by hot heading. | hot-headed rivet |
| 2904 | Tubular rivet | A rivet with a hollow shaft. | tubular rivet |
| 2905 | Semi-tubular rivet | A tubular rivet with a hollow section approximately 90% of the shaft diameter. Head shapes include flat, truss, flat, countersunk, and round. | semi-tubular rivet |
| 2906 | Full-tubular rivet | A tubular rivet in which the length of the hollow section exceeds 1.12 times the shaft diameter. | full tubular rivet |
| 2907 | Split-end rivet | A rivet with a longitudinal split at the end of the shank. | split rivet |
| 2908 | Blind rivet | A rivet designed so that crimping occurs from the insertion side. | blind rivet |
| 2909 | Turnbuckle | A component featuring a right-hand thread at one end and a left-hand thread at the other, used to adjust the tension of wires, tie rods, and similar components. | turnbuckle |
| 2910 | Anchor Bolt | A bolt embedded in concrete to secure structural members or equipment. It is referred to as a structural double-threaded anchor bolt. | anchor bolt with rolled (machined) threads for structures |
| 2911 | Stud with Head | A stud embedded in concrete to secure structural members or equipment. It is used by welding. | headed stud |
| 2912 | Threaded plug | A plug with threads. 1) Pipe plug with tapered threads : A plug with tapered threads for pipes; the drive end is available in hexagonal head, square head, hexagonal socket, and square socket configurations. 2) Parallel thread plug : A plug with parallel threads; the drive end is available in hexagonal head, square head, and hexagonal socket configurations. | 1) pipe plug 2) screw plug |
Other Technical Documents
↓You can download the following technical documents as a single PDF file.
Specifications
Hole Machining, Tolerances, and Fits
Calculations, Conversions, Formulas, and Units
Machine Elements
- Hexagon Socket Head Cap Screw Standards List | Excerpt from JIS B 1176
- Shapes and Dimensions of Hexagon Socket Set Screws (Excerpt from JIS B 1177-1997)
- Shapes and Dimensions of Hex Bolts (Component Grade A) (Excerpt from JIS B 1180-1985)
- How to Use Hex Socket Set Screws
- Mechanical Properties of Steel Bolts and Screws (Excerpt from JIS B 1051-2000)
- Shapes and Dimensions of Hexagonal Wrenches (Hex Wrenches/L-Wrenches/Hex Wrenches) (Excerpt from JIS B 4648:2008)
- List of Standards for Dimensions and Tolerances of Parallel Keys and Keyways (Excerpt from JIS B 1301-1996/JIS B 1301-1959 [Old JIS])
- Snap Rings (C-Type Retaining Rings/C-Rings) Standards and Dimensions List (Excerpt from JIS B 2804-2010)
- Shim Dimensions
- Ball Bearing Standard Dimensions Table - JIS Excerpt
Material Properties
Terminology
- Glossary of Electromagnetic Clutch and Electromagnetic Brake Terms (Excerpt from JIS B 1404-1:2005)
- Glossary of Screw Terms (JIS B 0101:2013)
- Glossary of Fit Tolerances (Excerpt from JIS B 0401-1:2016)
- Glossary of Terms for Chains, Sprockets, and Accessories (Excerpt from JIS B 1812:2015)
- Glossary of Friction Belt Transmission Terms (Excerpt from JIS B 1860:2018)
- Technical Drawing—Terminology (Excerpt from JIS Z 8114:1999)