The Flat Head Screw Advantage: 60-Degree Metric Precision

Flat-head screws are used for high-strength, high-precision assemblies. The standard angle for metric flat-head screws is 90 degrees, as stated in the metric DIN standard DIN963 for flat-head Phillips and slotted flat-head screws. However, the standard angle for metric flat-head socket cap screws in sizes M22 and M24 is 60 degrees, according to DIN 7991. These screws feature extremely high tensile and yield strength due to their alloy composition and heat treatment.

Flat head screws are used for high-strength, high-precision assemblies

Flat-head screws are used for high-strength, high-precision assemblies. They are characterised by a flat top and bottom, with a cone-shaped or countersunk head. This design allows the head of the screw to sit flush or below the surface of the material into which it is being driven. Flat-head screws are often used when a completely flush profile is required.

The standard angle for metric flat-head screws is 90 degrees, as stated in the metric DIN standard DIN963 for flat-head Phillips and slotted flat-head screws. However, flat-head socket cap screws in metric sizes M22 and M24 have a standard angle of 60 degrees, according to DIN 7991.

Flat-head screws are available in a range of materials, including A2 stainless steel, which offers good strength and high corrosion resistance, making it suitable for harsh applications. For heavy-duty applications, Grade 10.9 Steel is often used, as it is heat-treated and features high strength and durability. Grade 12.9 Steel is another option for flat-head screws, as it is also heat-treated and offers a 20-25% increase in tensile strength over Grade 10.9.

The choice of driver for flat-head screws depends on the size and material of the screw. Common driver types include socket, slotted, and Phillips. Slotted head screws tend to strip less than Phillips, especially in harsh environments, and are typically better for applications where the screw will need to be periodically unscrewed and redone. Phillips head screws, on the other hand, offer a stronger joint since they can tolerate more torque.

The standard angle for metric flat head screws is 90 degrees

Flat head screws, also known as countersunk screws, can be manufactured with 6 different angles: 60°, 82°, 90°, 100°, 110°, and 120°. The chamfered angles of 82° and 90° are the most commonly used. The standard 82° angle for imperial screws is different from the metric standard, and this is important to note when selecting the correct screw for a project.

The standard angle for metric flat head screws is also dependent on the size of the screw. Flat head socket cap screws in metric sizes M3-M20 have a standard angle of 90° according to DIN 7991. However, for larger screws, the standard angle changes. For metric sizes M22 and M24, the standard angle is 60° as per DIN 7991.

The angle of a flat head screw is an important consideration when working with thin materials. A larger angle, such as 100°, is often used for aerospace applications and softer materials as it distributes pressure over a larger area. This can be beneficial when working with materials that require a lighter touch or have less thickness to work with.

In summary, while there are variations and different standards for specific screw sizes, the standard angle for most metric flat head screws is 90 degrees. This standard is an important consideration when selecting the correct screw for a project, especially when working with thin materials or when the holding strength of the screw is a critical factor.

Flat head screws can be made from A2 stainless steel, grade 10.9 steel, or grade 12.9 steel

Flat head screws are versatile fasteners that can be made from various materials, including A2 stainless steel, grade 10.9 steel, and grade 12.9 steel. Each material offers distinct advantages and is suitable for different applications.

A2 stainless steel is a premium option known for its excellent corrosion resistance and strength. Flat head screws made from A2 stainless steel are ideal for outdoor environments and applications where durability and aesthetics are important. They are commonly used in automotive, outdoor equipment, and industrial machinery. The flat head design ensures a flush finish, providing a smooth and professional appearance.

Grade 10.9 steel is an alloy steel that offers high strength and is often used in applications where strength is a primary consideration. Flat head screws made from grade 10.9 steel are suitable for projects that require strong and reliable fastening solutions. They are available in various sizes and finishes to meet specific project requirements.

Grade 12.9 steel is also an alloy steel, composed of quenched and tempered alloy steel. It is known for its exceptional strength and is commonly used when strength is the most important factor. Flat head screws made from grade 12.9 steel are available in different sizes and finishes, such as black oxide, to suit specific project needs.

When choosing the appropriate material for flat head screws, it is essential to consider the specific requirements of your project. Factors such as corrosion resistance, strength, and aesthetics play a crucial role in selecting the right material. Additionally, the size, thread type, and finish of the screws should be carefully chosen to ensure compatibility with the application.

By understanding the unique properties of each material, you can make an informed decision about which type of flat head screw is best suited for your specific application, ensuring the integrity and longevity of your project.

Flat head screws can be coated with black oxide, mechanical zinc, or zinc-bake

Flat Head Screws and Coatings

Flat-head screws are a type of fastener used in a variety of applications, from wood and metal to electronics and automotive. They are characterised by their flat head design, which allows them to sit flush with the surface of the material they are screwed into. One of the key considerations when choosing flat-head screws is the type of coating or finish applied to the screw. Different coatings offer varying levels of protection, corrosion resistance, and aesthetic appeal. Here are some of the most common coatings for flat-head screws:

Black Oxide Coating

Black oxide-coated flat head screws are popular for their corrosion resistance and sleek black finish. The black oxide coating provides a layer of protection against rust and abrasion, making it ideal for both indoor and outdoor use. This type of coating is often applied to stainless steel screws, enhancing their corrosion resistance and giving them a clean, black appearance. Black oxide flat head screws are commonly used in applications where a discreet or decorative finish is desired, such as furniture, decking, or even saltwater environments.

Mechanical Zinc Coating

Mechanical galvanizing, also known as mechanical plating, is a process where small parts, including screws, are tumbled in a drum with zinc, glass beads, and chemicals. This method results in a matte gray, rough finish on the screws. Mechanical zinc coating offers similar corrosion protection to hot-dip galvanizing, making it suitable for fasteners that require high tensile strength and resistance to hydrogen embrittlement. This type of coating is often used for fasteners in moderate to harsh environments, providing a balance between protection and cost-effectiveness.

Zinc-Bake Coating

Zinc-bake coating, also known as zinc plating or electroplating, involves the electro-deposition of zinc onto the surface of the screw. This process results in a smooth, bright, and tightly adherent zinc coating. Zinc-bake coated screws are typically used for small fasteners in interior applications or mild external environments. The coating thickness can vary, and it is directly related to the longevity of the screw. To improve longevity or alter the appearance, zinc-plated screws can be post-treated with a chromate conversion coating, resulting in colours such as clear, blue, yellow, or black.

Making the Right Choice

When choosing a coating for flat-head screws, it is important to consider the specific application and environment in which the screws will be used. Each type of coating has its own advantages and is suitable for different levels of corrosion protection, aesthetic appeal, and cost. By understanding the unique characteristics of each coating, you can make an informed decision to select the most appropriate flat-head screws for your project.

Flat head screws can be purchased from Home Depot, Extreme Bolt, and Metric Screws

Flat-head screws are used for a wide range of applications, from wood-to-wood fastening to heavy-duty industrial uses. They are characterised by a flat top and bottom, with a cone-shaped or countersunk head. This allows the screw to sit flush or below the surface of the material it is being used on. Flat-head screws can be purchased from Home Depot, Extreme Bolt, and Metric Screws.

Home Depot

Home Depot stocks flat-head screws for interior wood-to-wood fastening. The screws are made of zinc-plated carbon steel and are sold in packs of 100. They are designed to efficiently join two pieces of wood together and are recommended for applications where a flat, smooth surface is required after installation.

Extreme Bolt

Extreme Bolt offers flat-head screws in a range of materials, including:

• A2 Stainless Steel, which features good strength and high corrosion resistance for harsh applications
• Grade 10.9 Steel, which is heat-treated and ideal for heavy-duty applications
• Grade 12.9 Steel, which is also heat-treated and offers a 20-25% tensile strength increase over Grade 10.9

Metric Screws

Metric Screws provides flat-head screws for high-precision, high-strength assemblies. The V-shaped 82-degree head allows the screw to be countersunk, creating a flush profile. The screws are made of alloy and feature extremely high tensile and yield strength. They are available in a wide range of materials and finishes to protect against corrosion.

Frequently asked questions