Category Archives: Thread Protection

Bespoke Bolts, Bespoke Fasteners, Thread data, Thread Forms, Thread Protection

High-Performance Fasteners: The Ultimate Thread Form Guide

Essential thread types for high performance fasteners

Understanding thread types is critical for selecting fasteners that meet performance, safety, and compatibility requirements. This guide outlines the most common thread systems used in bolts, nuts, and studs—including Metric, Unified, UNJ, UNR, and Whitworth forms.

For over 50 years, Hague Fasteners has manufactured precision threaded fasteners in steels, stainless steels, and superalloys. Therefore, we know how thread selection affects strength, fatigue life, seal integrity, and interchangeability.

How to Identify a Thread

  • System: Metric ISO, Unified, Whitworth, Pipe, Trapezoidal, Buttress
  • Diameter and Pitch: Metric uses mm pitch; Unified/Whitworth use TPI (threads per inch)
  • Series: Coarse, Fine, Extra Fine, Special
  • Class of Fit: Metric (6g, 6H); Unified (1A/1B to 3A/3B)
  • Form Geometry: ISO/Unified 60°, Whitworth 55°, UNJ/UNR radiused root, ACME 29°, Trapezoidal 30°
  • Hand/Starts: Right or left-hand, single or multi-start

Metric & Metric Fine Threads (ISO, 60°)

Metric threads use pitch in millimetres. Coarse “M” is standard. Fine “MF” improves preload control and engagement in thin sections.

Size Coarse Pitch (M) Common Fine Pitches (MF) Angle Notes
M6 1.0 0.75 60° General purpose
M8 1.25 1.0 60° Machinery, structures
M10 1.5 1.25, 1.0 60° Better clamp control
M12 1.75 1.5, 1.25 60° Thin sections
M16 2.0 1.5, 1.0 60° Vibration resistance
M20 2.5 2.0, 1.5 60° Flanged joints
M24 3.0 2.0, 2.5 60° Pressure boundary
M30 3.5 2.0, 2.5, 3.0 60° Large studs

FAQs on Metric Threads

  • What’s the difference? Metric Fine has smaller pitch for better preload control.
  • When to use MF? Thin walls, short engagement, vibration resistance.
  • Same angle? Yes—both use 60° flank angle.

Unified Threads UNC & UNF (ASME B1.1, 60°)

Size (inch) UNC (TPI) UNF (TPI) Angle Notes
1/4 20 28 60° General fixtures
3/8 16 24 60° Preload control
1/2 13 20 60° Structural fasteners
5/8 11 18 60° Studs, couplings
3/4 10 16 60° Pressure equipment
1 8 12 60° Heavy joints

FAQs on UNC & UNF Threads

  • What’s the difference? UNC is coarse, easier to assemble. UNF is fine, better clamp control.
  • Which is stronger? Depends on application—UNC for depth, UNF for engagement.
  • Same angle? Yes—60° flank angle.

UNJ & UNR Threads (ASME, 60°)

UNJ threads feature a controlled root radius for improved fatigue strength. UNJC is coarse pitch, UNJF is fine pitch. UNR is a rounded-root version of UNC/UNF.

FAQs on UNJ & UNR Threads

  • UNJ vs UNJF? UNJF is fine pitch within the UNJ family.
  • UNJC vs UNJF? UNJC is coarse pitch, same root radius.
  • What is UNR? Easier to roll, less controlled than UNJ but fatigue resistant.
  • Where used? Aerospace, defence, rotating equipment.

Whitworth Threads BSW & BSF (BS 84, 55°)

Whitworth threads use a 55° flank angle with rounded crests and roots. BSW is coarse; BSF is fine.

FAQs on BSW & BSF Threads

  • BSW vs BSF? BSF has finer pitch for thin sections.
  • Interchangeable? No—Whitworth differs from Metric/Unified.
  • Where found? Legacy British equipment, restoration, heritage plant.

Get in Touch

Contact Hague Fasteners today for a custom quote or technical consultation.

Hague Fasteners Limited do not take any responsibly for any information used

Technical Bulletins, Thread Protection

Screw Thread and Bolt Protection

Screw Thread Protection for Engineered Components

Thread Protection

One of the most common forms of damage to engineered components is screw thread damage. Screw threads are an integral part of many components, and any damage to them can have far-reaching consequences. In this article, we will detail the problems caused by damaged screw threads in engineered components commonly caused by poor bolt protection during packaging and shipping.

Screw Thread Protection for Engineered Components

Engineered components are crucial in various industries, from automotive to safety-critical Nuclear and Defence installations. These components are designed to perform specific functions with a high degree of precision and reliability. However, when these components are damaged during packaging and shipping, it can cause significant problems.

The Problems Caused by Damaged Screw Threads

The primary function of screw threads is to provide a secure and reliable connection between components. Any damage to the threads can compromise this connection and result in several issues.

Firstly, damaged threads can cause the component to fail prematurely. When the connection between components is not secure, it can cause the assembly to become loose or dislodged, resulting in a malfunction or failure. This can be particularly dangerous in critical applications, where a single component failure can have catastrophic consequences.

Secondly, damaged threads can result in increased maintenance costs. If a component fails prematurely due to damaged threads, it will need to be replaced or repaired. This can result in increased downtime, lost productivity, and increased costs.

Thirdly, damaged threads can result in reduced efficiency. When the connection between components is not secure, it can result in vibrations, which can cause wear and tear on the component. This can result in reduced efficiency and increased energy consumption.

Bolt Protection

The Extra Efforts Hague Fasteners Go To Protecting Threads and Precision Turned Parts

One such method is by wax dipping them to prevent knocks and damage after manufacturing. Wax dipping is a process where the component is dipped into a bath of hot wax to create a protective coating. This coating provides a layer of protection that can prevent damage from knocks and bumps during shipping and handling. It also helps to prevent moisture and other contaminants from penetrating the component, which can cause corrosion or other forms of damage, giving up to 10 years of extended rust prevention in storage.

Wax dipping is an effective and cost-efficient way to protect engineered components, especially threads, during shipping and handling. By taking this extra step, we can ensure that our components are received in perfect condition, ready to perform their intended function with reliability and precision. This protection is far more effective than the Extruded Mesh Sleeves sometimes applied to threaded parts.

Screw Thread and Bolt Protection, Damaged Threads Summary

Damaged screw threads in engineered components can cause significant problems, including premature component failure, increased maintenance costs, and reduced efficiency. That’s why it’s essential to protect components during shipping and handling to prevent damage from occurring. At Hague Fasteners, we go the extra mile to protect our components by wax dipping them to prevent knocks and damage after manufacturing. By doing so, we can ensure that our components are received in perfect condition, ready to perform their intended function with reliability and precision.