M6-1 x 25mm Class 8.8 Hex Cap Screws: Specs and Uses

Quick answer

An M6-1 x 25mm hex head cap screw is a fully threaded metric fastener with a 6mm nominal diameter, 1mm pitch, and 25mm length, made from Class 8.8 steel with a yellow zinc finish. It suits light-to-medium machinery assembly and general fastening where a wrench or socket drive is practical.

Frequently asked questions

What does Class 8.8 mean for this screw?

Class 8.8 indicates a metric property class with a nominal tensile strength of 800 MPa and a yield strength of 640 MPa. It is a medium-carbon steel grade suitable for most general fastening, but not for critical high-stress applications where Class 10.9 or 12.9 might be specified. Check your application's strength requirements before substituting a lower class.

What torque should I use for an M6 cap screw?

There is no single torque value without knowing the mating material and lubrication. As a starting point for Class 8.8 zinc-plated screws into steel, a torque around 8–10 N·m is often used, but always confirm with your engineering guidelines or a torque table for your specific joint. Use a calibrated torque wrench and verify values for your exact joint.

Is this screw fully threaded or partially threaded?

This M6-1 x 25mm screw is fully threaded, meaning the thread extends from under the head to the tip. That makes it versatile for clamping various thicknesses and for use in tapped holes or with nuts. Fully threaded screws are less suitable for applications needing an unthreaded shank for shear strength.

What are typical uses for an M6-1 x 25mm hex cap screw?

Common applications include securing brackets, panels, small machinery components, and general equipment assembly where a 10mm wrench or socket is accessible. The hex head allows for higher torque than a socket head of the same size. Ensure there is enough clearance for a socket or wrench during installation.

Does the yellow zinc finish affect torque values?

Yes, plated finishes can affect friction and therefore the torque-tension relationship. Yellow zinc may have different lubricity than plain steel or other coatings. If your application is torque-critical, test or consult a torque table that accounts for zinc plating. When replacing a plain screw with a zinc-plated one, re-evaluate torque settings.

Product facts

• M6-1 X 25mm Hex Head Cap Screws | Class 8.8 Steel Yellow Zinc | Fully Threaded (400 / Pkg.): Class 8.8 steel with yellow zinc CR+6 finish, fully threaded, sold in packs of 400. Class 8.8 offers a good balance of strength and cost for general industrial fastening, and the 400-piece pack suits assembly operations or maintenance stock.