Thread Forming Screws.

What are Thread Forming Screws?

Thread forming screws, also known as thread rolling screws, are innovative fasteners that create their own strong, reliable machine threads by displacing material rather than cutting it. Unlike traditional self-tapping screws that chip away material to create a thread (generating swarf), a thread forming screw 'rolls' and cold-forms the host material.

Accu's lines of thread forming screws feature a specialised trilobular (three-lobed) shank. This unique shape allows softer materials, like plastics or sheet metals, to cold flow into the recesses of the thread as the screw is driven in. This process forms a perfectly mated, high-strength thread that is exceptionally resistant to vibrational loosening, enhancing the reliability of the final assembly.

How Thread Forming Screws Work

The functionality of a thread forming screw is both simple and highly effective. The screw is driven directly into a pre-drilled, untapped pilot hole in a ductile material. As the trilobular screw advances, it applies pressure to the wall of the hole, displacing the host material and causing it to flow into the screw's own thread valleys. This action forms a precise, secure machine thread without removing any material.

It eliminates the need for a separate, time-consuming tapping operation, increases production efficiency and creates a zero-swarf joint, which is critical in sensitive electronic, medical or mechanical assemblies.

A perfect real-world example is in the assembly of modern electronic enclosures. Instead of pre-tapping dozens of holes in a plastic housing, a thread forming screw for plastic is used to create a strong, reliable fastening in a single, fast operation, saving valuable time and ensuring components remain secure for the product's lifespan.

Materials Thread Forming Screws Are Made From

Selecting the right material and finish is crucial for ensuring project performance and longevity. Our plastic thread forming screws are available in high-strength steel with specialised finishes to meet your application's demands:

• Steel (Bright Zinc Plated): Offers excellent strength and a standard level of corrosion resistance, making it a reliable choice for general-purpose indoor applications.
• Steel (Black Zinc Plated): Provides the same robust performance and corrosion protection as BZP steel, but with a sleek black finish ideal for aesthetic consistency or low-reflectivity requirements.

Sizes and Types of Thread Rolling Screws Available

Our dynamic range of thread forming screws for metal and plastic is precision-engineered to support projects of all sizes, from prototyping to large-scale production. We offer a comprehensive selection of imperial and metric thread forming screws for plastic, ensuring a precise fit for your design.

Covering multiple head types, including hexagon, cap, pan and countersunk heads, paired with high-torque, reliable drive types such as hexagon, hex socket, Torx, and Pozi drives, ensuring efficient and secure installation.

Our stock includes metric threads from M2 (2mm) to M10 (10mm) and imperial threads from 2-56 UNC to 1/4-20 UNC. With lengths available from 4mm up to 60mm (or 3/16" to 2 1/2"), you can source the exact specs you need to bring your project to life.

FAQs

Q: What materials are suitable for use with thread rolling screws?

A: Thread rolling screws are designed for use in softer, ductile materials. This includes most thermoplastics (such as ABS, nylon and polycarbonate) and malleable metals like aluminium, brass, copper and thin-gauge sheet steels. The fastener's success depends on the material's ability to 'cold flow' around the threads.

Q: Are thread forming screws self-tapping?

A: Yes, but they represent an advanced type of self-tapping screw. A conventional self-tapping screw functions like a tap by cutting and removing material to form a thread, which creates waste swarf. A thread forming screw is different; it displaces the host material without cutting it, resulting in a stronger, cleaner, zero-swarf joint that inherently resists loosening.

Q: What does a thread forming screw look like?

A: At a glance, a trilobular thread rolling screw may resemble a standard machine screw. However, the key difference is its innovative shank, which typically features a trilobular (three-lobed) cross-section. This specialised shape is what enables the screw to form threads by displacement. They are available with all common head types, including cap, pan, countersunk and hexagon heads.

Bespoke Thread Forming Screws Manufacture.

High precision, bespoke manufacture of Thread Forming Screws to customer specification. State of the art facilities specialising in both small batch prototyping and large scale manufacture.