Flank angle
The flank angle of a thread is measured between the mutually facing flanks of two adjacent thread turns.
Functions
The size of the flank angle is selected to match the application area of the thread type.
- Buttress and trapezoidal threads have a smaller flank angle and are used as movement threads. The small flank angle reduces friction and thus improves the efficiency and smoothness of threads that are moved regularly.
- Pointed threads with 60 ° and Whitworth threads with 55 ° have a larger flank angle and are usually used as fastening threads . The larger flank angle results in greater friction and thus better self-locking against unintentional loosening of the screw connection.
Overview of thread types
The ACME trapezoidal thread (USA) with a flank angle of 29 ° differs only slightly from the metric ISO trapezoidal thread commonly used in Europe , which has a flank angle of 30 °.
Standardized threads
(Partly taken from DIN 202 )
| designation | standardization | angle | profile | Identification letters | Example short name | application |
|---|---|---|---|---|---|---|
| Metric ISO thread / pointed thread | DIN 13 | 60 ° |  |
M. | M8
M8x1 |
Screw connections |
| Metric tapered male thread | DIN 158 | 60 ° |  |
M. | for screw plugs and grease nipples | |
| Pipe thread , parallel | DIN EN ISO 228-1 | 55 ° |  |
G | G1 3 ⁄ 4 | Pipe connections |
| Whitworth thread , taper ratio 1:16 | DIN EN 10226-2 | 55 ° | R. | R 1 ⁄ 2 | Pipe connections | |
| tapered Whitworth thread, 3:25 tapered | DIN EN 144-1 | 55 ° | E. | E 17 con | Screw-in socket of gas cylinder valves | |
| tapered Whitworth thread | DIN 477-1 | 55 ° | W. | W 28.8 × 1 ⁄ 14 | Screw-in socket of gas cylinder valves | |
| cylindrical Whitworth thread | DIN 49301 | 55 ° |  |
W. | W 3 ⁄ 16 | for D-screw adapters D II and D III in electrical engineering |
| Metric ISO trapezoidal thread | DIN 103 | 30 ° |  |
Tr | Door 14 × 3 | z. B. on machine tools (including turning and milling machines) |
| ACME connection , ACME trapezoidal thread | 29 ° |  |
Adapter for refueling with LPG | |||
| Flat thread / machine thread | 0 ° |  |
Sq | Machines (totally outdated, replaced by trapezoidal thread DIN 103) | ||
| metric buttress thread | DIN 513 (DIN514 fine thread) | 30 ° |  |
S. | S 10 × 2 | when absorbing forces acting on one side, pressing |
| British buttress thread / ANSI buttress thread | DIN 2781 | 45 ° |  |
S. | S 25 x 1.5 | for hydraulic presses |
| Round thread | DIN 405 / DIN 20400 | 30 ° |  |
Rd | Rd 8 × 1 ⁄ 10 " | low notch effect , tolerance to contamination, for example for coupling threads between railway wagons |
| Electric thread / Edison thread | DIN 40400 (E14 to E33), DIN EN 60061-1 for lamp bases E5, E10 and E40, DIN EN 60399 | E. | E 14 | D-fuses, E 14 and E 27 also for lamp sockets | ||
| Steel armored pipe thread | DIN 40430 | 80 ° |  |
Pg | Pg 21 | Previously electrical installations. Replaced in this application area by metric ISO threads |
| Self-tapping screw thread | DIN 7970 | 60 ° | ST | Sheet metal screws | ||
| Self-tapping screw thread | DIN EN ISO 1478 | 60 ° | ST | ST 3.5 | for sheet metal screws | |
| Wood screw thread | DIN 7998 | 60 ° | without | 4th | for wood screws | |
| Bicycle thread | DIN 79012 | 60 ° | FG | FG 2 | Cycles | |
| Valve thread | DIN 7756 | 60 ° | Vg | Vg 11 | Valves | |
| Glass thread | DIN 40450 | 35 ° / 50 ° | Glass | Glasg 74.5 | Electrical engineering for protective glasses and caps | |
| RMS thread | DIN 58888 | 55 ° | RMS | RMS | Lens connection for microscope lenses | |
| tapered drill pipe thread | DIN 20314 | 60 °, 1: 4 conical | Gg | Gg 4 1 ⁄ 2 | for deep drilling technology and mining | |
| Threads for bone screws and nuts | DIN 58810 | without | HA HB |
HA 4.5 HB 6.5 |
Bone screws and nuts for surgical implants | |
| Threads for bone screws and nuts | DIN 58810 | without | HB | HB 6.5 | Bone screws and nuts for surgical implants |
Thread according to works standard
| designation | standardization | angle | profile | Identification letters | Example short name | application |
|---|---|---|---|---|---|---|
| Cross thread / reversible spindles | according to company standard (DIN?) | according to the drawing | according to the drawing | according to the drawing | according to the drawing | Winding and unwinding of ropes in crane construction or of yarn threads on bobbins in the textile sector without reversing the direction of rotation. |