This is UNC
The expression ‘UNC threaded’ may have different meanings in a number of areas, but is most commonly used in the context of thread standards. UNC stands for ‘Unified National Coarse’, a thread standard developed by the American National Standards Institute (ANSI). UNC stands for ‘Unified National Coarse’, a thread standard developed by the American National Standards Institute (ANSI). This thread standard is widely used in various mechanical connections, such as bolts, nuts, screws and other fasteners.
UNC – Subprocesos gruesos unificados
Roscas UNC según ANSI B1.1:
| Diámetro mayor (pulgadas) | Hilos por pulgada (tpi) | Diámetro mayor | Tamaño del taladro de rosca (mm) | Paso (mm) | |
|---|---|---|---|---|---|
| (en) | (milímetros) | ||||
| #1 – 64 | 64 | 0.073 | 1.854 | 1.50 | 0.397 |
| #2 – 56 | 56 | 0.086 | 2.184 | 1.80 | 0.453 |
| #3 – 48 | 48 | 0.099 | 2.515 | 2.10 | 0.529 |
| #4 – 40 | 40 | 0.112 | 2.845 | 2.35 | 0.635 |
| #5 – 40 | 40 | 0.125 | 3.175 | 2.65 | 0.635 |
| #6 – 32 | 32 | 0.138 | 3.505 | 2.85 | 0.794 |
| #8 – 32 | 32 | 0.164 | 4.166 | 3.50 | 0.794 |
| #10 – 24 | 24 | 0.190 | 4.826 | 4.00 | 1.058 |
| #12 – 24 | 24 | 0.216 | 5.486 | 4.65 | 1.058 |
| 1/4″ – 20 | 20 | 0.250 | 6.350 | 5.35 | 1.270 |
| 5/16″ – 18 | 18 | 0.313 | 7.938 | 6.80 | 1.411 |
| 3/8″ – 16 | 16 | 0.375 | 9.525 | 8.25 | 1.587 |
| 7/16″ – 14 | 14 | 0.438 | 11.112 | 9.65 | 1.814 |
| 1/2″ – 13 | 13 | 0.500 | 12.700 | 11.15 | 1.954 |
| 9/16″ – 12 | 12 | 0.563 | 14.288 | 12.60 | 2.117 |
| 5/8″ – 11 | 11 | 0.625 | 15.875 | 14.05 | 2.309 |
| 3/4″ – 10 | 10 | 0.750 | 19.050 | 17.00 | 2.540 |
| 7/8″ – 9 | 9 | 0.875 | 22.225 | 20.00 | 2.822 |
| 1″ – 8 | 8 | 1.000 | 25.400 | 22.85 | 3.175 |
| 1 1/8″ – 7 | 7 | 1.125 | 28.575 | 25.65 | 3.628 |
| 1 1/4″ – 7 | 7 | 1.250 | 31.750 | 28.85 | 3.628 |
| 1 3/8″ – 6 | 6 | 1.375 | 34.925 | 31.55 | 4.233 |
| 1 1/2″ – 6 | 6 | 1.500 | 38.100 | 34.70 | 4.233 |
| 1 3/4″ – 5 | 5 | 1.750 | 44.450 | 40.40 | 5.080 |
| 2″ – 4 1/2 | 4 1/2 | 2.000 | 50.800 | 46.30 | 5.644 |
| 2 1/4″ – 4 1/2 | 4 1/2 | 2.250 | 57.150 | 52.65 | 5.644 |
| 2 1/2″ – 4 | 4 | 2.500 | 63.500 | 58.50 | 6.350 |
| 2 3/4″ – 4 | 4 | 2.750 | 69.850 | 64.75 | 6.350 |
| 3″ – 4 | 4 | 3.000 | 76.200 | 71.10 | 6.350 |
| 3 1/4″ – 4 | 4 | 3.250 | 82.550 | 77.45 | 6.350 |
| 3 1/2″ – 4 | 4 | 3.500 | 88.900 | 83.80 | 6.350 |
| 3 3/4″ – 4 | 4 | 3.750 | 95.250 | 90.15 | 6.350 |
| 4″ – 4 | 4 | 4.000 | 101.600 | 96.50 | 6.350 |
Characteristics:
UNC threads have a coarse thread (Coarse):
Compared with Fine (usually expressed as UNF), UNC thread has a larger pitch (i.e. the axial distance between two adjacent teeth at two points on the median line), so it has stronger connection strength and higher efficiency, and is suitable for occasions that need to withstand a larger load or need to be assembled quickly.
Uniform standards for UNC threads:
UNC threads follow a uniform national standard, which ensures that threaded parts produced by different manufacturers can be matched and interchanged, and improves the universality and standardisation of products.
UNC threads are widely used:
UNC threads are widely used in various fields such as automotive, aerospace, machinery manufacturing, construction, etc. They are an indispensable part of industrial production and daily life.
UNC thread marking:
UNC thread markings usually include information such as thread diameter (major diameter), pitch and thread grade. For example, the marking of a UNC thread may be ‘1/2-13 UNC 2B’, where ‘1/2’ means that the thread diameter is 1/2 inch, and ‘13’ means that the number of teeth per inch is 13, i.e., the number of teeth per inch is 13, i.e., the number of teeth per inch is 13. The ‘1/2’ indicates a 1/2 inch thread diameter, the ‘13’ indicates 13 teeth per inch, i.e., a pitch of 1/13 inch, the ‘UNC’ indicates a uniform coarse thread, and the ‘2B’ indicates the grade of the thread (the higher the grade, the higher the accuracy).
Note on UNC threads:
When selecting and using UNC threads, it is necessary to ensure that the parameters of the thread diameter, pitch and grade match the connection to avoid loosening or damage to the connection due to mismatch.
The processing and testing of UNC threads need to follow the appropriate national standards and process specifications to ensure the quality and accuracy of the threads.
This is UNF
UNF threaded, or Unified National Fine threaded, which stands for Unified Fine Threaded, is a threading standard jointly developed by the American National Standards Institute (ANSI) and the Threaded-Products Manufacturers Institute (TPI). Compared with UNC (Unified National Coarse threaded), UNF threaded has the following characteristics:
UNF threaded with fine threads:
UNF threaded threads have a small pitch (i.e. the axial distance between two points on the median line corresponding to two adjacent threads), which gives them a significant advantage in the field of high-precision manufacturing.
UNF – Hilos finos nacionales unificados
Roscas UNF ANSI B1.1:
| Diámetro mayor (pulgadas) | Hilos por pulgada (tpi) | Diámetro mayor | Tamaño del taladro de rosca (mm) | Paso (mm) | |
|---|---|---|---|---|---|
| (en) | (milímetros) | ||||
| #0 – 80 | 80 | 0.060 | 1.524 | 1.25 | 0.317 |
| #1 – 72 | 72 | 0.073 | 1.854 | 1.55 | 0.353 |
| #2 – 64 | 64 | 0.086 | 2.184 | 1.90 | 0.397 |
| #3 – 56 | 56 | 0.099 | 2.515 | 2.15 | 0.453 |
| #4 – 48 | 48 | 0.112 | 2.845 | 2.40 | 0.529 |
| #5 – 44 | 44 | 0.125 | 3.175 | 2.70 | 0.577 |
| #6 – 40 | 40 | 0.138 | 3.505 | 2.95 | 0.635 |
| #8 – 36 | 36 | 0.164 | 4.166 | 3.50 | 0.705 |
| #10 – 32 | 32 | 0.190 | 4.826 | 4.10 | 0.794 |
| #12 – 28 | 28 | 0.216 | 5.486 | 4.70 | 0.907 |
| 1/4″ – 28 | 28 | 0.250 | 6.350 | 5.50 | 0.907 |
| 5/16″ – 24 | 24 | 0.313 | 7.938 | 6.90 | 1.058 |
| 3/8″ – 24 | 24 | 0.375 | 9.525 | 8.50 | 1.058 |
| 7/16″ – 20 | 20 | 0.438 | 11.112 | 9.90 | 1.270 |
| 1/2″ – 20 | 20 | 0.500 | 12.700 | 11.50 | 1.270 |
| 9/16″ – 18 | 18 | 0.563 | 14.288 | 12.90 | 1.411 |
| 5/8″ – 18 | 18 | 0.625 | 15.875 | 14.50 | 1.411 |
| 3/4″ – 16 | 16 | 0.750 | 19.050 | 17.50 | 1.587 |
| 7/8″ – 14 | 14 | 0.875 | 22.225 | 20.40 | 1.814 |
| 1″ – 12 | 12 | 1.000 | 25.400 | 23.25 | 2.117 |
| 1 1/8″ – 12 | 12 | 1.125 | 28.575 | 26.50 | 2.117 |
| 1 1/4″ – 12 | 12 | 1.250 | 31.750 | 29.50 | 2.117 |
| 1 3/8″ – 12 | 12 | 1.375 | 34.925 | 32.75 | 2.117 |
| 1 1/2″ – 12 | 12 | 1.500 | 38.100 | 36.00 | 2.117 |
UNF threaded for high precision:
Due to the small pitch, UNF threaded can provide higher connection precision and sealing, and is suitable for applications that require high connection strength and sealing.
UNF threaded for a wide range of applications:
Although UNF threaded is mainly used in high-precision areas, it is also widely used in a variety of mechanical components that require fine connections, such as precision instruments, aerospace equipment, medical equipment, etc.
UNF threaded marking and parameters:
The marking of UNF threads usually includes information such as thread diameter (major diameter), pitch and thread grade. For example, a UNF thread may be identified as ‘1/4-20 UNF 2A’, where ‘1/4’ means that the thread diameter is 1/4 inch and ‘20’ means that the number of teeth per inch is 20, i.e., the number of threads per inch is 20, i.e., the number of threads per inch is 20. UNF’ means Unified Fine Thread, and “2A” means the grade of the thread (the higher the grade, the higher the accuracy).
UNF threaded Caution:
When selecting and using UNF threads, it is necessary to ensure that the parameters such as diameter, pitch and grade of the thread match the connection to avoid loosening or damage to the connection due to mismatch.
The machining and testing of UNF threads needs to follow the appropriate national standards and process specifications to ensure the quality and accuracy of the threads.
What is the difference between UNC v UNF?
UNC (Unified National Coarse threaded) and UNF (Unified National Fine threaded) are two different thread standards and there are obvious differences between them, mainly in the following aspects:
Pitch
UNC: Coarse threads, which have a relatively large pitch. This means that UNC threads have fewer teeth in the same length.
UNF: Fine threads, which have a relatively small pitch. For the same length, UNF threads have more teeth.
Range of application
UNC: Due to its larger pitch, the UNC thread is usually used where a stronger and more efficient connection is required. It is suitable for a wide range of materials and workpieces, and is especially widely used in mechanical engineering, automotive manufacturing, aerospace, etc. UNC threads have a high connection strength and are able to meet most engineering requirements.
UNF: Due to the small pitch, UNF thread is more suitable in applications requiring higher precision and sealing. It is commonly used in precision instruments, medical equipment and mechanical components that require delicate connections. In addition, UNF threads are widely used in many industries due to their excellent wear resistance and versatility.
Thread Marking
Thread markings differ between the two, and usually include information such as thread diameter, pitch and thread grade. For example, a UNC thread may be labelled ‘1/2-13 UNC 2B’, while a UNF thread may be labelled ‘1/4-20 UNF 2A’.
Machining and Installation
UNC: Because of their larger pitch, UNC threads are generally easier and quicker to machine and install, increasing productivity.
UNF: Although UNF threads can be a little more complicated to machine, their uniform specification and fine thread characteristics ensure good interchangeability and versatility, making them more widely used in different industries and regions.
If you are interested in UNC or UNF and would like to know more please contact our engineers.
