---

Westfield Fasteners Product Specification:

ISO 7380 part 1 - Socket Head Button Screws

This product guide contains the specification for metric threaded socket head button screws as available from Westfield Fasteners. The basis of this specification is the ISO standard ISO 7380, but this specification may include information on sizes and materials that are not covered by the ISO standard but are available.

Product Description

A popular and attractive socket head screw, typically used where aesthetics are important, or where a lower profile domed finish is required. The hex drive is generally smaller than other hex driven ranges and thus the ultimate tightening torque is reduced. These socket button screws are generally manufactured with a fully threaded shank, but occasionally we are provided with stock with a partial thread.

Scope of the ISO Standard

ISO standard 7380 part 1 specifies the tolerances and the permissable variation in form of hexagon socket button head screws, and covers metric thread diameters from M3 up to and including M16. Mechanical properties for these items are defined in ISO 898 and ISO 3506. Table 1 below defines the overall dimensions and tolerances of this screw type. Table 2 defines the tolerances on the shank length, whilst table 3 shows the reduced minimum ultimate tensile loads for this product. The information in table 3 is presented here because due to their head design socket button screws are considered to have reduced loadability over other screw types, as defined in ISO 898 and ISO 3506. ISO 7380 part 2 is a seperate standard that covers hexagon socket button screws with a flange.

Notes to figure 1:

• The small radius between the head and the shank (rs) is very slightly greater for the full threaded version than it is for the partial threaded shanked version. This is an important detail, as the button head may not sit fully flush on the surface, without a countersink or washer present.
  
  
• A slight rounding or countersink at the mouth of the socket may be present.
  
  
• On the top of the domed head, surrounding the socket, is a small flat area. The diameter of this area (dL) can vary between batches. This dimension is not definitive, and is offered as a reference only.

Variations from ISO 7380 part 1

This specification includes information on hexagon socket button screws with an M2.5 thread. This thread size is not covered in ISO 7380 part 1.

Manufacturer and/or material markings may be present on the domed part of the head.