"}},{"@type":"Question","name":"What does \"unf thread\" mean?","acceptedAnswer":{"@type":"Answer","text":"UNC stands for unified course pitch threads whereas UNF stands for unified fine pitch threads. UNF threads are distinguished by having more threads per distance than UNC threads. While both UNC and UNF bolts are used for fastening, they are often applied in different fields due to their unique advantages."}},{"@type":"Question","name":"How to read UNC threads?","acceptedAnswer":{"@type":"Answer","text":"If you are using the Unified Thread Series, it is easy to tell the threads major diameter, threads per inch (TPI) and if the thread is coarse or fine pitch from the thread specification. As an example, a 1/4\"-20UNC thread has a 1/4\" major diameter, with 20 threads per inch (TPI) and is a UNC coarse pitch thread."}},{"@type":"Question","name":"Is 5 16 18 unc or unf?","acceptedAnswer":{"@type":"Answer","text":"Threads in the UNC, UNF & UNEF designations have a fixed number of threads per inch (tpi) for a special diameter. For example, 5/16” UNC has 18 tpi, 5/16” UNF has 24 tpi, and 5/16” UNEF has 32 tpi."}},{"@type":"Question","name":"What does 10/32 unf mean?","acceptedAnswer":{"@type":"Answer","text":"
10-32 UNF is a Unified National Fine (UNF) thread with a 10-32 thread pitch:
UNF: Represents a Unified National Fine thread
10: A size designator with no numerical meaning
32: Refers to the 32 threads per inch (TPI) pitch
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The 10-32 UNF thread originates from the Unified and American Screw Threads for Bolts, Nuts, and Machine Screws standards published in 1974 by ANSI B1.1. A 10-32 screw can be identified by measuring its diameter at exactly 3/16 in (4.76 mm) with a ruler. The screw should have 32 full-thread revolutions for every inch in length.
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May 3, 2021 — Figure 1 Credit: Atlantic Fasteners. Taking the 10-32 thread as an example, the...
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Jun 1, 2020 — 12-24 Threaded Screw – ICACSS01BK – active 12-24 is more common than 10-32. 12-
"}},{"@type":"Question","name":"What is UNF best for?","acceptedAnswer":{"@type":"Answer","text":"UNF students achieve a higher overall pass rate (compared to state and national averages) on licensure exams for physical therapists, athletic trainers, registered dietitians and nurse practitioners."}},{"@type":"Question","name":"What is the major and minor diameter of a thread?","acceptedAnswer":{"@type":"Answer","text":"
The major diameter of a thread is the largest diameter of a screw or nut thread, while the minor diameter is the smallest. The major diameter is measured from the crests of the thread, while the minor diameter is measured from the roots. For external threads, the minor diameter can also be measured from root to root.
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Unless otherwise stated, threads have a flank angle of 30°, resulting in a total angle bet...
The major diameter is also known as the outside diameter for screw threads and the full diameter for nut threads. The minor diameter is also known as the root diameter.
MW Components
Basic Screw and Thread Terms | MW Components
Major Diameter: The largest diameter of the thread of the screw or nut. The term “major di...
Wikipedia
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The major diameter Dmaj is the diameter of the screw measured from the outer edge of the t...
The major and minor diameters of a screw can help determine if it's the right size for a fastening application. For example, when choosing a cap for a thread, you can look for one with an inside diameter that's 1-2 sizes smaller than the major diameter. For tapered plugs, you can try to match the minor diameter of the plug to the middle diameter of the hole.
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Sep 29, 2021 — Checking a screw's minor and major thread diameters will allow you to determin...
"}},{"@type":"Question","name":"What is the major diameter of a 6/32 thread?","acceptedAnswer":{"@type":"Answer","text":"Detailed Description. The 505 screw is a #6-32 screw with a major thread diameter of #6, which is defined as 3.51 mm (0.138 in.)."}}]}}
Thread Chart (UNF-UNC) - Major and Minor Diameters (2024)
Thread Chart (UNF-UNC) - Major and Minor Diameters
By Lee Lechner
May 16, 2022
There are various thread types and sizes to choose from these days. Occasionally, you need to know the dimensions associated with those threads, so we're developing posts like this one to make it easy for you.
You'll find a quick reference chart for UNC/UNF - Unified National Threads in this post. If you're new to any of the terminology, scroll down past the chart, and you'll find a list of definitions to help you better. The chart below will focus on the major diameters for external threads and the minor diameters for internal threads. We've included the image below to show these areas better.
THREAD CHART (UNF-UNC THREADS)
Thread Designation
UNF / UNC
Threads per Inch
Basic Major Diameter
(External Threads)
Basic Minor Diameter
(Internal Threads)
0-80
UNF
80
0.060
0.047
1-64
UNC
64
0.073
0.056
2-56
UNC
56
0.086
0.067
2-64
UNF
64
0.086
0.069
4-40
UNC
40
0.112
0.085
5-40
UNC
40
0.125
0.098
5-44
UNF
44
0.125
0.100
6-32
UNC
32
0.136
0.104
6-40
UNF
40
0.136
0.111
8-32
UNC
32
0.164
0.130
8-36
UNF
36
0.164
0.134
10-24
UNC
24
0.190
0.145
10-32
UNF
32
0.190
0.156
1/4-20
UNC
20
0.250
0.196
1/4-28
UNF
28
0.250
0.211
5/16-18
UNC
18
0.313
0.252
5/16-24
UNF
24
0.313
0.267
3/8-16
UNC
16
0.375
0.307
3/8-24
UNF
24
0.375
0.330
7/16-14
UNC
14
0.438
0.360
7/16-20
UNF
20
0.438
0.383
1/2-13
UNC
13
0.500
0.417
1/2-20
UNF
20
0.500
0.446
9/16-12
UNC
12
0.563
0.472
9/16-18
UNF
18
0.563
0.502
5/8-11
UNC
11
0.625
0.527
5/8-18
UNF
18
0.625
0.565
3/4-10
UNC
10
0.750
0.642
3/4-16
UNF
16
0.750
0.682
7/8-9
UNC
9
0.875
0.755
7/8-14
UNF
14
0.875
0.798
1-8
UNC
8
1.000
0.865
1-14
UNF
14
1.000
0.910
1 1/8-7
UNC
7
1.125
0.970
1 1/8-12
UNF
12
1.125
1.035
1 1/4-7
UNC
7
1.250
1.095
1 3/8-6
UNC
6
1.375
1.195
1 1/2-6
UNC
6
1.500
1.320
1 3/4-5
UNC
5
1.750
1.534
2-4.5
UNC
4 1/2
2.000
1.759
Download Full Standard Thread Chart
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Basics of UNF and UNC Threads
UNF and UNC threads are the most common types of UN (Unified National) threads.
UNC Threads
UNC threads are unified coarse pitch threads.
Less likely to cross-thread
Faster assembly and disassembly (Generally used in mass production)
Large thread allowances allow for thicker platings & coatings
Fewer threads per distance compared to fine threads
UNF Threads
UNF threads are unified fine pitch threads.
Allow for closer adjustment accuracy due to the smaller helix angle
Require less torque to develop equivalent bolt preloads
Fine thread is stronger in both tension (due to larger stress area) and shear (larger minor diameter)
Less tendency to loosen since the thread incline is smaller
Generally used for applications that need high fastener strength
Thread Fit
Thread fit is a measure of looseness or tightness of mating thread. It is specified to designate the amount of tolerance allowance and installation fit desired. There are three different classes of thread fit that they come in:
Classes 1A (external) & 1B (internal): Extremely loose tolerance thread fit. This class is meant for quick and easy assembly/disassembly. (Not Commonly Specified)
Classes 2A (external) & 2B (internal): Optimum thread fit that balances performance, manufacturing, economy, and convenience. (Most common - Nearly 90% of all commercial & industrial fasteners use this class of thread fit
Classes 3A (external) & 3B (internal): Meant for close tolerance fasteners where the accuracy of thread elements is important, and safety is a critical design consideration
Using Chart for Choosing Masking Caps & Plugs
There's a variety of different reasons you may have needed to reference the chart, so we hope it was useful for you! Here at Echo, we use it to help powder coaters, e-coaters, anodizers, and platers find the correct sized cap or plug for their specific thread size. So, here are a few tips in case you ever need it.
Cap It
The simple version of finding the right size cap is that we suggest finding one that has an ID (inside diameter) that is 1-2 sizes smaller than the Major Diameter of the thread you're masking off. You want to get a tighter fit for processes like e-coat.
Plug It
For tapered plugs, you'll want to closely match the minor diameter to the middle diameter of the plug (see graphic). If it's not exact, seat the plug deeper in the hole. When you install these plugs, you push them in and then turn them to get a better seal.
UNF threads are fine threads, so this will require more turns to tighten the plug into the hole. UNC threads arecoarse threads, so they require fewer turns to tighten the seal.
VIDEO: How to Mask Threaded Holes
About Echo Engineering
Echo Engineering has been providing masking solutions to industrial finishers for well over 50 years. Because of that, we are frequently working closely with paint lines to help them find ways of masking off threaded holes and bolts. We specialize in not only standard catalog options, like powder coating tapes, caps, and plugs, but also in designing, engineering, and manufacturing custom solutions for some of the largest metal finishing lines in the world.
If you're in need of a masking solution or simply have a question you'd like to ask us, please fill out the form below and we will get back to you as soon as possible!
Connect with our team of pros!
We'd love to help you solve your company's biggest production challenges.
Let us know what project you're working on and how our team can help you create the best solution!
Connect with our team of pros!
We'd love to help you solve your company's biggest production challenges.
Let us know what project you're working on and how our team can help you create the best solution!
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Threads UNC UNF
Posted in Powder Coating, Masking Threads, E-Coating and Plating
Major Diameter: The largest diameter of the thread of the screw or nut. The term “major diameter” replaces the term “outside diameter” as applied to the thread of a screw and also the term “full diameter” as applied to the thread of a nut. Minor Diameter: The smallest diameter of the thread of the screw or nut.
Fields of application: UNC threads are often used in applications that require fast fastening and adjustment, such as mechanical engineering and construction. UNF threads are more suitable for applications that require high precision and strength, such as aerospace, automotive manufacturing and electronic equipment.
What is the difference between UNF and NPT? Thread type: UNF is a fine thread, while NPT is a pipe thread. UNF threads have a finer pitch and have more threads per inch, while NPT threads have a coarser pitch.
Here are the formulas that we use to find those maximum and minimum diameters: For external thread major diameter (d): d max = d + e s d_\text{max} = d + es dmax=d+es. d min = d + e s − T d d_\text{min} = d + es - T_\text{d} dmin=d+es−Td.
Thread sizes can be read in different ways depending on the type of thread:
Screw threads
To determine the size of a screw thread, you can measure the major diameter of the screw and the distance between two adjacent threads at their peaks. Then, combine these two measurements to get the screw size. For example, if the major diameter is ¼ in and there are 20 threads per inch, the screw size is ¼ in x 20. If the diameter is less than ¼ in, the screw size is usually indicated by a number, such as #10 or No. 10. For example, a 10-24 screw has a thread diameter of 0.190 in and 24 threads per inch.
Thread count
Thread sizes can also be indicated by a number that follows the Gunze Count standard. For example, a 50/2 thread is thinner than a 30/2 thread, and the larger the number, the finer the thread. The second number in the thread count indicates the number of strands, or plies, that are twisted together.
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UNC stands for unified course pitch threads whereas UNF stands for unified fine pitch threads. UNF threads are distinguished by having more threads per distance than UNC threads. While both UNC and UNF bolts are used for fastening, they are often applied in different fields due to their unique advantages.
If you are using the Unified Thread Series, it is easy to tell the threads major diameter, threads per inch (TPI) and if the thread is coarse or fine pitch from the thread specification. As an example, a 1/4"-20UNC thread has a 1/4" major diameter, with 20 threads per inch (TPI) and is a UNC coarse pitch thread.
Threads in the UNC, UNF & UNEF designations have a fixed number of threads per inch (tpi) for a special diameter. For example, 5/16” UNC has 18 tpi, 5/16” UNF has 24 tpi, and 5/16” UNEF has 32 tpi.
10-32 UNF is a Unified National Fine (UNF) thread with a 10-32 thread pitch:
UNF: Represents a Unified National Fine thread
10: A size designator with no numerical meaning
32: Refers to the 32 threads per inch (TPI) pitch
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UNF stands for Unified National Fine, a thread standard developed by the American National Standard (ANSI). UNF threads are a type of Unified Screw Thread, which is a classification system agreed upon by the United States, Great Britain, and Canada in 1949 to ensure interchangeability. UNF threads are fine pitch threads, which means they have more threads per distance than UNC threads, which are coarse pitch threads.
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UNF threads are often used in applications that require high-precision connections and fastening, such as in the aerospace, automotive, and precision instrument manufacturing industries. They have several advantages over other types of threads, including:
Closer adjustment accuracy
UNF threads have a smaller helix angle, which allows for more precise adjustments.
Less torque required
UNF threads require less torque to develop the same bolt preload as other threads.
Greater strength
UNF threads are stronger in both tension and shear than other threads, due to their larger stress area and minor diameter.
Less likely to loosen
UNF threads have a smaller thread incline, which makes them less likely to loosen.
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UNC and UNF threads no longer use millimeters (mm) but inches ("). This is because they are American threads and they work with the Imperial system as opposed to the for us more familiar metric system.
10-32 UNF is a Unified National Fine (UNF) thread with a 10-32 thread pitch:
UNF: Represents a Unified National Fine thread
10: A size designator with no numerical meaning
32: Refers to the 32 threads per inch (TPI) pitch
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The 10-32 UNF thread originates from the Unified and American Screw Threads for Bolts, Nuts, and Machine Screws standards published in 1974 by ANSI B1.1. A 10-32 screw can be identified by measuring its diameter at exactly 3/16 in (4.76 mm) with a ruler. The screw should have 32 full-thread revolutions for every inch in length.
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UNC - Unified Coarse Thread. The old definition NC is comparable with the metric thread. The new term UNC is comparable with the ISO metric thread. NC and UNC threads are interchangeable, in an analogous manner like the metric and the ISO metric thread.
Introduction: My name is Merrill Bechtelar CPA, I am a clean, agreeable, glorious, magnificent, witty, enchanting, comfortable person who loves writing and wants to share my knowledge and understanding with you.
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