#12-32 UNEF Thread Quick Specifications
| Parameter | Specification | |
| Thread Standard | Unified Thread Standard (UTS) | |
| Thread Series | UNEF | |
| Nominal Size | 12 | |
| Thread Designation | #12-32 UNEF | |
| Threads Per Inch (TPI) | 32 | |
| Major Diameter | 0.2160 in | 5.486 mm |
| Pitch | 0.0313 in | 0.795 mm |
| Pitch Diameter | 0.1957 in | 4.971 mm |
| Minor Diameter | 0.1788 in | 4.542 mm |
| Thread Height | 0.0169 in | 0.429 mm |
| Addendum | 0.0101 in | 0.257 mm |
| Thread Angle | 60° | |
| Common Classes | 2A / 2B | |
| Typical Use | Precision electronic assemblies | |
Introduction
The #12-32 UNEF thread is one of the most widely used Unified National Extra Fine (UNEF) thread sizes in high-reliability electronic equipment, particularly for thread-mount feedthrough capacitors, EMI filters, RF shielding assemblies, and other precision panel-mounted components.
The #12-32 UNEF thread has a nominal major diameter of 0.216 inches (5.486 mm), a pitch of 0.0313 inches (0.795 mm), and 32 threads per inch (TPI). The most common tolerance class is 2A for external threads and 2B for internal threads .
This page provides a complete engineering reference for #12-32 UNEF thread dimensions and specifications, including thread designation, major diameter, pitch, threads per inch (TPI), minor diameter, and tolerance classes.
For engineers selecting threaded mounting solutions for electronic components such as feedthrough filters, EMI filters, RF shielding components, and precision assemblies, understanding the #12-32 UNEF specification helps ensure proper mechanical compatibility, reliable installation, and long-term performance. The threaded mounting design ensures excellent grounding to the equipment enclosure, improving shielding effectiveness and overall EMC performance
Quick Answer:
The #12-32 UNEF thread is one of the most widely used Unified National Extra Fine (UNEF) thread sizes in high-reliability electronic equipment, particularly for thread-mount feedthrough capacitors, EMI filters, RF shielding assemblies, and other precision panel-mounted components.
A #12-32 UNEF thread is a Unified National Extra Fine (UNEF) screw thread defined by the Unified Thread Standard (UTS).
The designation means:
- 12indicates the nominal major diameter
- 32indicates 32 threads per inch (TPI)
- UNEFindicates Unified National Extra Fine thread series — characterized by the finest pitch for its nominal diameter within the Unified thread series, offering maximum precision and vibration resistance
#12-32 UNEF Thread Tolerance Classes
Thread tolerance determines how tightly two mating components fit together.
The Unified Thread Standard defines several tolerance classes.
Class 2A / 2B Threads
Class 2 is the most commonly used commercial tolerance.
External Thread: #12-32 UNEF-2A
Internal Thread: #12-32 UNEF-2B
Advantages:
- Good interchangeability
- Reliable assembly
- Suitable for mass production
- Lower manufacturing cost
Typical applications:
- EMI filter mounting
- Feedthrough capacitor installation
- Industrial electronic equipment
- General instrumentation
Most commercial fasteners use Class 2.
Class 3A / 3B Threads
Class 3 provides a tighter fit.
External Thread: #12-32 UNEF-3A
Internal Thread: #12-32 UNEF-3B
They are typically selected when requirements include:
- Higher positional accuracy
- Reduced movement between mating parts
- Precision adjustment
- Aerospace or military specifications
However, tighter tolerances also mean:
- Higher machining requirements
- More expensive inspection
- Greater sensitivity to contamination
#12-32 UNEF vs Similar Thread Sizes
Engineers often need to determine whether another thread specification can replace #12-32 UNEF.
#12-32 UNEF vs M5 × 0.8
| Parameter | #12-32 UNEF | M5 × 0.8 |
| Standard | Unified | Metric ISO |
| Major Diameter | 5.486 mm | 5.000 mm |
| Pitch | 0.795 mm | 0.800 mm |
| Pitch Diameter | 4.971 mm | 4.480 mm |
| Minor Diameter | 4.542 mm | 4.134 mm |
| Thread Height | 0.429 mm | 0.433 mm |
| Thread Angle | 60° | 60° |
Frequently Asked Questions (FAQ)
Q1. What is the difference between UNF and UNEF?
The difference is thread pitch. UNEF has more threads per inch than UNF. UNEF is typically used where precision and compact mounting are required.
Q2. What tolerance class is commonly used for #12-32 UNEF?
The most common tolerance class is:
- External thread: #12-32 UNEF-2A
- Internal thread: #12-32 UNEF-2B
Class 3A/3B is used when tighter precision is required.
Q3. Is #12-32 UNEF suitable for EMI filters?
Yes. It is commonly used in:
- Feedthrough capacitors
- Thread mount EMI filters
- RF shielding components
- Panel-mounted electronic assemblies
Its fine pitch allows compact installation and reliable mechanical retention.
Engineering Support CTA: Selecting a threaded EMI filter or feedthrough capacitor? Share the thread standard and size, panel thickness, voltage/current, capacitance, and environmental requirements with LCA engineers. View Thread Mount Feedthrough Filters
