Metric Socket Cap Screws

What Are Metric Socket Cap Screws?

A metric socket cap screw is a fully threaded fastener with a cylindrical head and an internal hex socket drive, installed with an Allen wrench or hex bit rather than a standard screwdriver. The socket drive lets the screw sit flush or recessed into a counterbore, which keeps the fastening point clean and low-profile.
Socket cap screws are built for high-strength fastening. Their head design distributes torque evenly through the socket, so they can be tightened to high clamp loads without stripping or rounding out, even in smaller sizes. That combination of strength and a compact head makes them the go-to choice for limited-clearance applications where a hex bolt head simply won't fit.

Metric Socket Cap Screw Types

DIN 7991 Metric Flat Socket Cap Screws

Flat socket cap screws have a countersunk head that sits fully flush with the surface once installed. We stock these in 12.9 alloy with thermal black oxide, mechanical zinc, and zinc bake finishes, as well as A2 and A4 stainless steel.

DIN 7984 Metric Low Head Socket Cap Screws

Low head socket cap screws use a shorter head height, useful when clearance is tight but a full countersink isn't needed. Available in 10.9 and 8.8 alloy with thermal black oxide, and in A2 stainless steel.

DIN 912 / ISO 4762 Metric Socket Cap Screws

The standard metric socket head cap screw. Alloy versions rated to Class 12.9 offer significantly higher tensile strength than a comparable Class 8.8 hex bolt, while requiring less surface area since the head is internally wrenched. We carry these in 12.9 and 8.8 alloy across black oxide and zinc finishes, plus A2 stainless steel.

ISO 7379 Metric Socket Shoulder Screws

These pair an unthreaded shoulder with a shorter threaded end, acting as a locating pin or pivot point for jigs, fixtures, and moving assemblies. Available in 12.9 alloy with thermal black oxide, and in 18-8 stainless.

ISO 7380 Metric Button Socket Cap Screws

Button head socket cap screws have a low, rounded dome head, a common choice when a lower profile is preferred but a fully countersunk flat head isn't necessary, such as covers, guards, and lighter-duty assemblies. Stocked in 12.9 alloy with black oxide and zinc finishes, plus A2 and A4 stainless steel.

Metric Socket Cap Screw Materials and Finishes

Material and finish choice affects both strength and corrosion resistance, so we stock a range of options to match different environments and load requirements:

• Alloy steel, in 12.9, 10.9, and 8.8 grades, for a range of tensile strengths
• Thermal black oxide for a low-cost coating
• Zinc bake CR+3, zinc bake CR+6, and mechanical zinc CR+3 finishes for improved corrosion resistance on alloy steel screws
• Stainless steel A2 for general corrosion resistance in indoor and moderate outdoor environments
• Stainless steel A4 for stronger corrosion resistance in marine, washdown, or chemically-exposed settings
• 18-8 stainless for a cost-effective stainless option in standard-duty applications

Common Metric Socket Cap Screw Applications

Metric socket cap screws are used across virtually every industrial sector where an assembly needs precise torque from a low-profile fastener. Typical applications include:

• Machinery
• Tooling and fixturing
• Dies / die sets
• Vehicle applications
• General engineering assemblies
• Mining and earth-moving equipment
• Applications requiring strength, precision, and limited wrench clearance

Why Work With RC Fastener for Metric Socket Screw Supply?

Since 2002, RC Fastener has been dedicated to providing our customers with superior quality products at great prices. When you partner with RC Fasteners as your metric socket head screw supplier, you can count on:

• Superior quality products backed by ISO 9001:2015 accreditation
• Fast turnaround and reliable shipping on in-stock orders
• Competitive pricing, with volume discounts available on bulk orders
• A knowledgeable team that's easy to reach and genuinely wants to help
• Support sourcing hard-to-find or made-to-print configurations
• Options for recurring supply and vendor-managed inventory on ongoing production needs

Contact Us to Learn More About Our Metric Socket Cap Screw Supply Options

Contact us for more information about how RC Fasteners can supply metric socket head cap screws for your application. Ready to order? Submit a quick quote online, and our team will be in touch.

Frequently Asked Questions About Metric Socket Cap Screws

What are metric socket cap screws used for?

Metric socket cap screws are used anywhere an assembly needs a high-strength fastener in a tight or low-clearance space. Common uses include machinery, tooling, dies, vehicle assemblies, and general engineering work where a standard hex bolt head wouldn't fit or wouldn't provide enough force.

What is the difference between DIN 912 and ISO 4762 socket cap screws?

DIN 912 and ISO 4762 describe the same basic socket head cap screw design and are largely interchangeable in most applications. DIN 912 is the older German standard, while ISO 4762 is the international standard that succeeded it. Minor dimensional differences can exist between the two, so it's worth confirming fit against a specific drawing on tight-tolerance jobs.

What materials are metric socket cap screws available in?

We stock metric socket cap screws in alloy steel with thermal black oxide or zinc finishes, plus A2 stainless, A4 stainless, and 18-8 stainless. Material choice depends on the strength and corrosion resistance the application calls for.

What tool is used to install socket cap screws?

Socket cap screws install with a hex key (Allen wrench) or a hex bit driven by a power tool. The internal hex socket allows for higher installation torque than a screwdriver-driven fastener, which is part of why socket cap screws can achieve such high clamp loads in a compact head.