Imperial hex head bolt UNC/UNF – partial thread

Inch bolts

Imperial hex head bolt UNC/UNF – partial thread

1,59 – 8,99 €

In stock — 494 pieces, ship immediately

The partially threaded imperial hex head bolt has a hexagonal head and a thread on only part of its length, leaving a plain shank under the head. It is made …

Available variants

DIN931 bolt 3/8"-UNCx3 FE 8.8 hex head, partially threaded, UNC thread (Unified National Coarse)

ERP code: 15686 · Catalogue number: DIN931-3/8UNCx3-FE8.8

Thread: 3/8"-UNC Length: 76.2 mm Pitch: 1.587 Strength grade: 8.8 Material: FE
1,79 € 17 pcs

DIN931 bolt 3/8"-UNCx2 1/2 FE 8.8 hex head, partially threaded, UNC thread (Unified National Coarse)

ERP code: 15685 · Catalogue number: DIN931-3/8UNCx2 1/2-FE8.8

Thread: 3/8"-UNC Length: 63.5 mm Pitch: 1.587 Strength grade: 8.8 Material: FE
1,66 € 83 pcs

DIN931 bolt 3/8"-UNFx2 FE 8.8 hex head, partially threaded, UNF thread (Unified National Fine)

ERP code: 45829 · Catalogue number: DIN931-3/8UNFx2-FE8.8

Thread: 3/8"-UNF Length: 50.8 mm Pitch: 1.058 Strength grade: 8.8 Material: FE
2,65 € 24 pcs

DIN931 bolt 5/16"-UNFx2 FE 8.8 hex head, partially threaded, UNF thread (Unified National Fine)

ERP code: 53907 · Catalogue number: DIN931-5/16UNFx2-FE8.8

Thread: 5/16"-UNF Length: 50.8 mm Pitch: 1.058 Strength grade: 8.8 Material: FE
2,59 € Out of stock

DIN931 bolt 5/8"-UNCx4 FE 8.8 hex head, partially threaded, UNC thread (Unified National Coarse)

ERP code: 47070 · Catalogue number: DIN931-5/8UNCx4-FE8.8

Thread: 5/8"-UNC Length: 101.6 mm Pitch: 2.309 Strength grade: 8.8 Material: FE
7,30 € 15 pcs

DIN931 bolt 5/8"-UNCx3 FE 10.9 hex head, partially threaded, UNC thread (Unified National Coarse)

ERP code: 50174 · Catalogue number: DIN931-5/8UNCx3-FE10.9

Thread: 5/8"-UNC Length: 76.2 mm Pitch: 2.309 Strength grade: 10.9 Material: FE
8,99 € 100 pcs

DIN931 bolt 5/8"-UNCx3 FE 8.8 hex head, partially threaded, UNC thread (Unified National Coarse)

ERP code: 46973 · Catalogue number: DIN931-5/8UNCx3-FE8.8

Thread: 5/8"-UNC Length: 76.2 mm Pitch: 2.309 Strength grade: 8.8 Material: FE
6,39 € Out of stock

DIN931 bolt 7/16"-UNCx2 FE 10.9 hex head, partially threaded, UNC thread (Unified National Coarse)

ERP code: 16554 · Catalogue number: DIN931-7/16UNCx2-FE10.9

Thread: 7/16"-UNC Length: 50.8 mm Pitch: 1.814 Strength grade: 10.9 Material: FE
1,99 € 100 pcs

DIN931 bolt 7/16"-UNCx1 3/4 FE 10.9 hex head, partially threaded, UNC thread (Unified National Coarse)

ERP code: 49397 · Catalogue number: DIN931-7/16UNCx1 3/4-FE10.9

Thread: 7/16"-UNC Length: 44.4 mm Pitch: 1.814 Strength grade: 10.9 Material: FE
1,59 € 100 pcs

DIN931 bolt 7/16"-UNCx1 1/2 FE 10.9 hex head, partially threaded, UNC thread (Unified National Coarse)

ERP code: 16553 · Catalogue number: DIN931-7/16UNCx1 1/2-FE10.9

Thread: 7/16"-UNC Length: 38.1 mm Pitch: 1.814 Strength grade: 10.9 Material: FE
1,59 € Out of stock

DIN931 bolt 7/16"-UNFx3 FE 8.8 hex head, partially threaded, UNF thread (Unified National Fine)

ERP code: 46081 · Catalogue number: DIN931-7/16UNFx3-FE8.8

Thread: 7/16"-UNF Length: 76.2 mm Pitch: 1.27 Strength grade: 8.8 Material: FE
4,65 € 55 pcs

The partially threaded imperial hex head bolt has a hexagonal head and a thread on only part of its length, leaving a plain shank under the head. It is made in inch (imperial) sizes with UNC coarse or UNF fine thread to ASME B1.1. Its design corresponds to the metric DIN 931 bolt, and in British terminology it is known as a hex bolt.

It is used in the maintenance and repair of machinery, vehicles, marine engines, agricultural and construction equipment, and any equipment built to inch dimensions, where a metric bolt is not a substitute.

When to choose a partial thread?

  • The plain shank carries lateral (shear) loads instead of the thread.
  • The shank passes easily through the hole and centres the joined parts.
  • The shank length should match the joint thickness so the nut can be tightened properly.
  • For joints of varying thickness or tapped holes, choose the fully threaded imperial hex head bolt.

UNC or UNF – what is the difference?

  • UNC (Unified National Coarse) – coarse thread with fewer threads per inch. Faster assembly and lower risk of thread damage; suited to general use and softer materials such as cast iron and aluminium.
  • UNF (Unified National Fine) – fine thread with more threads per inch and a smaller pitch. Better vibration resistance and a slightly larger tensile stress area; common in automotive, hydraulic and thin-walled applications.

Both threads have a 60° profile, but UNC and UNF bolts of the same diameter are not interchangeable.

How to read an imperial bolt designation

1/4"-20 UNC means: nominal diameter 1/4 inch (6.35 mm), 20 threads per inch (TPI), coarse thread. The same diameter with a fine thread is designated 1/4"-28 UNF.

Threads per inch (TPI) – UNC / UNF

  • 1/4" – 20 / 28
  • 5/16" – 18 / 24
  • 3/8" – 16 / 24
  • 7/16" – 14 / 20
  • 1/2" – 13 / 20
  • 5/8" – 11 / 18
  • 3/4" – 10 / 16
  • 1" – 8 / 12

Before ordering, check the diameter, threads per inch and bolt length. Select the size in the table below, and contact us if you need help choosing.

If you need more, please contact us

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