M4 x 8mm Pozi Countersunk Thread Forming Screws (DIN 7500M) - Black Stainless Steel (A2) Description
The M4 x 8mm Pozi Countersunk Thread Forming Screws (DIN 7500M) - Black Stainless Steel (A2) has the following features:
- Countersunk Angle (CA): 90 Degrees
- Drive Size: PZ2
- Matte Black Finish
- For Use With: Plastics, Thin Composite Materials, and Light Metals, e.g. Aluminium, Brass and Sheet Steel.
- Head Diameter (D): 8.4 mm
- Head Diameter (D) Tolerance: +0/-1.26 mm
- Head Length (H): 2.2 mm
- Length (L): 8 mm
- Manufacturing Standard: DIN 7500M
- Stainless Steel - (A2)
- Stainless Steel Material Family
- Not Suitable For Use With: Ferrous Metals
- Pitch: 0.7 mm
- System of Measurement: Metric
- Thread Size: M4 (4 mm)
- Thread Type: Trilobular
Discover more about the Pozi Countersunk Thread Forming Screws range.
Pozi countersunk thread forming screws, also known as Pozi countersunk thread rolling screws, are advanced self-threading fasteners engineered for high-efficiency assembly. Their defining feature is a specialist trilobular shaft, which is expertly designed to cold form its own mating threads when driven into an untapped pilot hole.
Equipped with a Pozi drive, these screws provide efficient torque transfer and reduce the risk of cam-out during installation. The countersunk head geometry allows the screw to sit perfectly flush with the component's surface for a professional, snag-free finish.
How Pozi Countersunk Thread Forming Screws Work
These screws are designed to make engineering faster by removing the need for a separate tapping operation. When driven into a correctly-sized pilot hole, the trilobular shape of the screw shaft applies precise pressure to roll and form a perfect machine thread within the host material.
This cold-forming action creates an exceptionally secure, vibration-resistant fastening. The resulting thread engagement is often stronger than a conventional pre-tapped hole because the material's grain structure is reformed rather than cut. It also crucially eliminates swarf, the metal chips and debris created by traditional tapping, ensuring a cleaner, more reliable assembly.
A real-world example is the assembly of electronic enclosures from thin sheet steel or aluminium. Instead of drilling, tapping, cleaning the swarf and then inserting a machine screw, an operator can simply drive a Pozi countersunk thread forming screw directly into the pilot hole. The screw creates its own thread and sits flush, all in a single, fast and clean action, dramatically improving production efficiency.
Materials Pozi Countersunk Thread Rolling Screws Are Made From
To ensure reliability across various applications, Accu's range of Pozi countersunk thread rolling screws is available in several high-performance materials:
- Stainless Steel (A2): Ideal for applications requiring strong corrosion resistance and durability, suitable for a wide array of engineering environments, indoors and out.
- Steel (Bright Zinc Plated): A cost-effective and popular choice, offering good indoor corrosion protection with a clean, silver finish.
- Steel (Black Zinc Plated): Provides similar corrosion resistance to BZP but with a non-reflective black finish, often preferred for aesthetic reasons or in electronic builds.
Sizes and Types of Pozi Countersunk Thread Forming Screws Available
To support projects of all sizes, from prototyping to large-scale production, our Pozi countersunk thread forming screws are available in a comprehensive range of dimensions. We stock metric thread sizes starting from M2.5 (2.5mm) and extending up to M8 (8mm). This variety is matched by a wide selection of lengths, running from 5mm to 50mm, ensuring you can find the precise component to meet your design's exacting standards.
FAQs
Q: Do I need to countersink the pilot hole for these screws?
A: Yes. The thread forming action of the screw only creates the threads inside the pilot hole. To allow the countersunk head to sit perfectly flush with your component's surface, you must first drill a separate countersunk recess into the pilot hole that matches the angle and diameter of the screw's head.
Q: What materials do these Pozi countersunk thread forming screws work in?
A: These screws are specifically designed for high-performance use in plastics, thin composite materials and light metals. They excel at creating reliable machine threads in materials like aluminium, brass and sheet steel, where traditional tapping would be slow or impractical.
