A Comprehensive Guide to Threaded Inserts

Threaded inserts are indispensable in many applications for secure fastening, reinforcement, and versatility. This comprehensive guide will delve deeper into threaded inserts, exploring their various types, installation methods, and extensive uses.
Tuesday, 10 October 2023
architectural hardware
A Comprehensive Guide to Threaded Inserts

Threaded inserts are indispensable in many applications for secure fastening, reinforcement, and versatility. This comprehensive guide will delve deeper into threaded inserts, exploring their various types, installation methods, and extensive uses.

What are threaded Inserts?

Threaded inserts are cylindrical metal components with internal or external threads that run the entire insert length. They are ingeniously designed to be inserted into pre-drilled metal, wood, or plastic holes. The primary objective of threaded inserts is to streamline the process of inserting screws or bolts, thereby ensuring easy and robust connections. These inserts serve as efficient fasteners and can be employed to strengthen or repair existing threads, guaranteeing a secure grip once they are firmly in place.

Threaded inserts are known by other alternatives like thread inserts, thread bushings, threaded sleeves, insert nut fixings, threaded fasteners, and screw thread inserts.

How to Install a Threaded Insert?

Installing a threaded insert is a straightforward process, but it requires some specific tools, including a drill and a matching installation tool, often called an install tap. These installation tools are typically designed to work seamlessly with specific insert manufacturers. Alternatively, one can utilize a matching threaded screw or tap bolt to drive the insert into its designated location. 

Here is a comprehensive breakdown of the steps involved in installing a threaded insert using a drill:  

  1. Prepare theDrill:

Ensure the drill is appropriately set up. If necessary, attach a depth stop attachment to regulate the drilling depth. The packaging usually guides the drill hole's required depth, typically between 8.5 and 9mm.

  1. Drill the Hole:

Carefully drill the hole to the specified depth, as indicated on the packaging.

  1. Insert and Drive:

Attach the installation tool or bolt to the insert's thread, then drive the insert into the hole. For added convenience and efficiency, consider using an impact driver.

  1. Optional Glue Reinforcement:

When applying a threaded insert to wood, adding glue for additional reinforcement can be beneficial, ensuring a robust and enduring connection.

Threaded inserts are categorized into two primary types: 'thread-in,' which involves screwing them into place, and 'press-in,' where they are pressed into position.

Types of Threaded Inserts

Threaded inserts exhibit diverse sizes and materials to accommodate various applications. Let's delve deeper into some common types of threaded inserts and their unique characteristics:

Brass Threaded Inserts

Renowned for their durability and exceptional corrosion resistance, brass inserts stand out as a robust choice, surpassing stainless steel in corrosion resistance. They are particularly well-suited for environments prone to water exposure.

Steel Threaded Inserts

They offer commendable corrosion resistance, but their resilience extends further. They excel in withstanding vibrations and rotational pressure, making them ideal for demanding applications.

Stainless Steel Threaded Inserts

Stainless steel inserts are a carefully calibrated alloy, incorporating 11 percent chromium to thwart corrosion and enhance heat resistance. These versatile inserts find their place in wood, metal, and plastic applications.

Clear Passivated Inserts

Clear passivated inserts feature a transparent protective coating with high-level corrosion resistance. Passivation, in this context, refers to applying a protective coating that renders the material less reactive to its environment.

Galvanized Inserts

Galvanized inserts sport a protective zinc coating, effectively preventing oxidation and rust formation.

Threaded Insert Uses

The applications of threaded inserts are remarkably diverse, and they serve a multitude of crucial functions. Here's a comprehensive overview of their uses:

Extending Hole Lifespan

Threaded inserts minimize wear and tear on drilled holes, allowing bolts and screws to be removed and reinserted multiple times without weakening the existing hole. This feature is precious in applications where frequent assembly and disassembly are required.

Repairing Worn Holes

Threaded inserts, often referred to as thread repair inserts, boast a larger diameter than the hole into which they are inserted. This design compresses the surrounding material, ensuring a tight and secure hold. They are instrumental in rehabilitating stripped or deteriorated holes.

Secure Grip in Soft Materials

Threaded inserts provide a secure hold in softer materials, preventing issues like stripping or pulling out of screws and bolts, which can occur when fastened directly into these materials.

Reinforcing Under Strain

In applications where screws or bolts are subjected to significant forces and strain, threaded inserts serve as essential reinforcements, ensuring connections remain solid and dependable.

Adding Threads to Thin Materials

Threaded inserts are invaluable for adding threads to materials that would otherwise be too thin to support direct fastening. They enhance the versatility and adaptability of materials in various applications.

Simplifying Thread Transitions

Threaded inserts streamline the transition from one type of thread to another. This is particularly beneficial in cases where compatibility between different thread types is necessary.

Threaded Insert Sizes

Threaded inserts are available in many thread sizes to accommodate screws and bolts of varying diameters. The most widely adopted international screw thread standard is the ISO metric screw thread, defined by international standards 68-1. In this system, ISO metric screws are designated by the letter "M," signifying millimeters, followed by the thread's primary diameter, representing the longest distance between the uppermost part of each thread (the crest).

For instance, "M8" indicates a significant diameter of eight millimeters. Variations in pitch can also be indicated using a multiplication sign, such as "M8x1," denoting an eight-millimeter primary diameter with a one-millimeter pitch change per rotation.


Threaded inserts are versatile and indispensable for applications across various industries and projects. By gaining a deeper understanding of the different types, installation methods, and sizes of threaded inserts, professionals can harness their full potential for a wide range of tasks. Whether you're extending the lifespan of drilled holes, rehabilitating threads, or fortifying connections under strain, threaded inserts are valuable assets in your toolkit, ready to enhance your projects' efficiency, durability, and reliability.


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