M6-1 x 50mm Socket Cap Screws: Sizing and Strength Guide
By Mutual Screw & Supply | Published: 2026-10-24
Category: Buying Guides
Learn the exact dimensions, strength class, and practical uses of M6-1 x 50mm socket cap screws. This guide helps you choose the right fastener for machinery, tooling, and precision assemblies.
Quick answer
The M6-1 x 50mm socket cap screw with a hex socket drive, partial threading, and Class 12.9 alloy steel zinc plating is a strong, corrosion-resistant choice for machinery, tooling, jigs, and precision assemblies where high tensile strength and a low-profile head are needed.
Why choose a partially threaded design?
A partially threaded socket cap screw has threads that stop before the head, leaving a smooth shank. This shank provides better shear strength and precise alignment in applications where the full thread is not needed along the entire length. For the M6-1 x 50mm screw, the unthreaded portion helps center components in jigs and tooling without galling.
Class 12.9 vs. lower grades
Class 12.9 is the highest standard property class for alloy steel socket cap screws, offering a minimum tensile strength of 1220 MPa. This makes it suitable for high-stress applications like engine components, heavy machinery, and structural clamps. However, it is more brittle than lower grades like 8.8 or 10.9, so avoid using it where dynamic shock loads or bending forces are common.
Zinc plating: pros and trade-offs
Zinc plating provides a protective barrier against corrosion in indoor or moderate environments. It also offers a consistent appearance and some lubricity during installation. The trade-off is limited corrosion resistance compared to stainless steel or hot-dip galvanized coatings. For outdoor or highly humid conditions, consider a different finish or add a protective coating.
Decision rules for choosing M6-1 x 50mm socket cap screws
- Check the thread length: For a partially threaded screw, measure the threaded portion to ensure it is long enough to engage the mating threads in your application. If the full length needs threads, choose a fully threaded alternative.
- Verify drive compatibility: Hex socket drive requires a hex key (Allen wrench) of the correct size. Ensure you have the right tool on hand and that the socket depth matches the driver.
- Match strength class to load: Class 12.9 is ideal for static or cyclic tensile loads. For applications involving impact or bending, consider a lower grade like 10.9 or 8.8 to reduce risk of brittle fracture. Always consult a fastener engineer for critical safety applications.
Product facts
- M6-1 X 50mm Socket Cap Screws | Hex Socket Drive | Partially Threaded | Class 12.9 Alloy Steel Zinc Plated (200 / Pkg.): These M6-1 x 50mm socket cap screws are manufactured from Alloy Steel Zinc Plated, featuring a hex socket drive. They are partially threaded and designed for machinery, tooling, jigs, and precision assemblies. The combination of Class 12.9 strength and zinc plating makes this screw a reliable choice for high-load indoor applications where corrosion resistance is still important.
M6-1 X 50mm Socket Cap Screws | Hex Socket Drive | Partially Threaded | Class 12.9 Alloy Steel Zinc Plated (200 / Pkg.)
Who should use this screw?
Best for
- Machinery and equipment assembly where high tensile strength is required
- Jigs, fixtures, and tooling where precise alignment and shear strength matter
- Indoor or sheltered environments needing moderate corrosion protection
Not for
- Applications with repeated shock or impact loads (choose a lower grade)
- Outdoor or highly corrosive environments without additional protection
- Applications requiring full thread engagement along the entire length
