M4 A2 Csk Socket Set Screws DIN 7991

Product Description

M4 A2 Stainless Steel Countersunk Socket Head Screws

These M4 countersunk socket head screws are manufactured from A2 stainless steel and feature a standard metric coarse M4 × 0.7 thread. The internal hexagon socket provides positive tool engagement, while the countersunk head is designed to sit flush within a correctly prepared countersink.

Manufactured to the dimensional form traditionally associated with DIN 7991. The current corresponding international standard is ISO 10642, adopted in Britain as BS EN ISO 10642.

Product Features

• Thread size: M4
• Thread pitch: 0.7mm metric coarse
• Material: A2 stainless steel
• Head style: countersunk flat head
• Drive type: internal hexagon socket
• Hexagon key size: 2.5mm
• Nominal head diameter: 8mm
• Nominal head height: 2.3mm
• Countersunk screw length is measured overall, including the head
• Available in lengths from 6mm to 50mm
• Legacy dimensional standard: DIN 7991
• Current standard: ISO 10642 / BS EN ISO 10642

Standards Information

DIN 7991 is the recognised legacy dimensional standard for hexagon socket countersunk head screws. The current corresponding standard is ISO 10642, adopted in Britain as BS EN ISO 10642.

Countersunk socket screws have reduced loadability compared with an equivalent fully loadable fastener because material is removed from the head to form the internal hexagon socket. They should not be substituted for a standard full-loadability fastener without checking the joint requirements.

A2 stainless steel offers good general corrosion resistance for indoor, outdoor and damp applications. For prolonged exposure to saltwater, swimming-pool environments or aggressive chemicals, A4 stainless steel may be more suitable.

Installation Guidance

Use a correctly fitting 2.5mm hexagon key and ensure that the countersink properly supports and aligns the screw head. Avoid overtightening, particularly in softer materials or applications with limited thread engagement.

Stainless steel fasteners can be susceptible to thread galling. Clean mating threads, avoid excessive installation speed and use a suitable anti-galling lubricant where appropriate.

Please note: Specifications are provided as a guide. If thread coverage, dimensions or standards compliance are critical to your application, please contact us before ordering.

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