RS PRO Pozi Countersunk Steel Machine Screws DIN 965, M4x20mm

From RS PRO a high-quality machine screw with a flat countersunk head for flush fitting and a versatile Pozidriv recess for a superior grip when tightening. This machine screw has a metric thread and is made from high-quality BZP (Bright Zinc Plated) steel which slows down rusting and corrosion

A machine screw is similar to a bolt but has a socket or slot in its head that allows it to be turned by a screwdriver. The shank on a machine screw is straight rather than tapered with a full thread which is uniform along the entire length. Machine screws do not tap their own thread into materials like wood screws do but are designed to be fastened into pre-tapped holes in the parts they are fastening together. Having a threaded hole creates a stronger joint and results in a higher quality product.

Countersunk machine screws, also known as CSK screws have a flat head design so when placed in a pre-drilled countersunk hole they will sit flush with or below the surface of the surrounding material. These screw heads are ideal for use when you need to cover the heads with a screw cap or create a flat surface for placing objects on or fixing other objects to.

Pozidriv, sometimes shortened to Pozi, stands for “positive drive”. This head type has a cross recess in the centre with four small indentations around it creating 8 points of contact. This design provides improved engagement and contact with the screwdriver and prevents ejection force when tightening or loosening the machine screw.

BZP is a shiny coating is applied to the steel, this process prevents corrosion and rusting. If the application is situated within a harsh environment, BZP will provide much-needed longevity and reliability. Although it may not be as effective as stainless steel, the added benefit would be the price. As stainless steel is completely rustproof but expensive, BZP Steel offers a great solution and is massively cost-effective.

• Pozidriv head type for improved screwdriver grip
• Countersunk head for a flush finish
• Bright Zinc Plated steel for resistance to corrosion
• Meets DIN 965 Standards

Machine screws are designed to hold separate components together in a wide range of applications such as industrial machinery and vehicle engines. They are screwed through pre-drilled tapped holes in 2 components and can be fastened at the rear with a nut. This bright zinc plated steel machine screw is ideal for domestic and commercial use. Applications include.

• Electrical panel building
• PCB Prototyping
• Circuit board mounting
• General production engineering
• General maintenance and repair.
• Light fastening applications

These measurements are found on metric screws, The 'M' stands for Metric. The number after the 'M' is the nominal outer diameter of the screw in mm.

Damage to the machine screw threads can prevent parts from fitting together properly, therefore care has to be taken when cutting them and the correct tools used.

Cutting a small machine screw (up to standard size #10 or metric size M5 (5mm)

Use a pair of multipurpose wire strippers or electricians pliers that feature M2.5, M3, M3.5, M4, M5 threaded holes. These holes are designed for cutting bolts without damaging the thread. Open the jaws and thread the machine screw into the correct size hole to the distance required. Squeeze the tool handles closed and the screw will be cut at the point where the two halves of the jaws come together. You will have a clean cut without any thread damage.

Cutting a large machine screw (larger than size #10 or metric size M5 (5mm)

This is best done using a hacksaw. Thread the nut on the screw until it reaches the desired point on the head side of the cutting line. Place the screw in a vice or clamp to keep it secure when cutting and cut the screw as straight as you can. When you unthread the nut it will repair and realign any threads that may have been damaged by the saw blade.

The function of this product requires the use of a screwdriver. To see the range of countersunk head machine screws please refer to the datasheet and range overview download sheet. Through these two documents you will also find the various thread sizes and lengths that we have to offer.
If bright zinc plated steel is not what you are looking for, we also offer the cross-recess and flat head machine screws in stainless steel and nickel plated brass, to find these please refer to the fasteners selection guide.

Threaded in accordance with DIN 965 standard

Please note IMDS is not a regulatory requirement and is currently not supported by RS PRO