M20 8.8 Zinc Plated Hexagon Set Screws DIN 933

Product Description

M20 × 2.5mm property class 8.8 zinc-plated steel hexagon-head set screws, fully threaded and manufactured to the traditional DIN 933 / current ISO 4017 dimensional pattern.

These high-tensile metric set screws feature a conventional external hexagon head and a full metric coarse thread extending along the usable length beneath the head. They are suitable for heavy machinery, structural brackets, agricultural equipment, automotive applications, steel fabrication, workshop maintenance and general engineering assemblies.

• Thread size: M20
• Thread pitch: 2.5mm metric coarse
• Threading: Fully threaded
• Available lengths: 50mm, 55mm, 60mm, 70mm and 200mm
• Head style: External hexagon head
• Width across flats: Approximately 30mm
• Head height: Approximately 12.5mm
• Recommended spanner or socket size: 30mm
• Material: High-tensile steel
• Property class: 8.8
• Finish: Zinc plated
• Traditional standard: DIN 933
• Current international standard: ISO 4017
• British adoption: BS EN ISO 4017
• Pack sizes available: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 50, 100, 250, 500 and 1000

These M20 hexagon-head set screws are suitable for heavy machinery, agricultural equipment, commercial vehicles, structural brackets, steel fabrication, plant maintenance and general engineering applications.

The standard M20 × 2.5mm metric coarse thread must be used with a corresponding M20 nut, threaded insert or tapped hole. It is not interchangeable with M20 metric fine threads such as M20 × 2.0mm or M20 × 1.5mm.

The fully threaded set-screw construction provides thread engagement along the usable length beneath the head. This makes the screws suitable for assemblies with varying material thicknesses and applications where a plain unthreaded shank is not required.

Property class 8.8 is a high-tensile steel fastener grade with a nominal tensile strength of approximately 800 N/mm² and a nominal yield-strength ratio of 0.8. The property class should be matched with a suitable nut and washer system for the intended joint.

Correct tightening torque depends on the joint design, lubrication, thread condition, mating materials, washer arrangement and required clamp load. Generic torque figures should not be applied without checking the requirements of the specific assembly.

The external hexagon head is installed using a correctly fitting 30mm spanner or socket. Ensure the tool is seated fully across the flats before applying torque to reduce the risk of rounding or damaging the head.

The zinc-plated finish provides improved corrosion resistance compared with untreated self-colour steel and is suitable for many indoor and sheltered outdoor applications. It is not normally recommended for prolonged exposure to marine, coastal or highly corrosive environments.

Hexagon set-screw length is measured from directly beneath the head to the end of the screw. The external hexagon head is not included in the stated length.

Please note: DIN 933 is the traditional product designation, while ISO 4017 is the current international standard and BS EN ISO 4017 is the corresponding British adoption. The 200mm length appears in the product selector but is not included in the existing dimensional table. The same nominal M20 head and thread dimensions have therefore been applied to this option. Specifications are intended as a guide only; check the fastener where fit, strength or dimensions are critical.

Please Note: Specifications given are intended as a guide only. If critical to your project please check with us first.