Application guide for Hex Head Bolts with Reduced Shanks to ISO 4015. The core duty of the type is an elastic bolted joint whose shank is reduced to about the pitch diameter so it stretches instead of the thread. The typical industries, the how-to-specify checklist, assembly practice and the exclusion cases are set out below. Stocked across roughly M3 to M20, they cover general to heavy-duty work.
Typical Applications for Hex Head Bolts with Reduced Shank
The most common settings where these are specified:
- Engine and compressor building: cylinder-head and housing joints that see repeated pressure cycles.
- Rail vehicles: bogie and underframe joints loaded by vibration.
- Pressure equipment: flanged covers that must keep preload through thermal cycling.
- Machine tools: spindle housings where settling would loosen a rigid bolt.
How to Specify Hex Head Bolts with Reduced Shank for Your Application
- Size: Match the nominal size to the mating thread or hole. This product spans M3–M20; check the full table below for the exact dimensions of each size.
- Strength class: Choose the property class (e.g. 8.8, 10.9, 12.9 or A2/A4 stainless) for the load and environment, and tighten to the matching torque so the joint relies on preload, not friction.
- Environment: For damp, coastal or chemical exposure prefer A4/316 stainless or a suitable coating; indoors, plated steel or A2 is usually sufficient.
- Standard: This product is supplied to ISO 4015. Quoting the standard on your order guarantees interchangeable dimensions between suppliers.
Installation & Assembly Practice
- Tighten to the torque for the size and property class with a calibrated wrench — the joint is held by preload, not by the thread friction alone.
- Ensure at least one full thread projects beyond the nut after tightening, and never re-use a bolt that has been tightened into yield.
- Under slotted or oversized holes, fit a hardened washer so the preload does not relax into the hole edge.
Common Selection Mistakes with Hex Head Bolts with Reduced Shank
- Specifying class 12.9 "to be safe" in a corrosive environment — high classes are more sensitive to hydrogen embrittlement and stress corrosion; 8.8 hot-dip galvanized often outlasts them outdoors.
- Choosing a length that puts the shear plane through the threaded portion when a plain shank (partially threaded bolt) was available.
- Mixing stainless bolts with plated-steel nuts: the joint loses its corrosion logic and can gall or seize.
Where Hex Head Bolts with Reduced Shank Are Not the Right Choice
Not for permanent joints that will never be opened (a rivet or weld is cheaper), and not where the head must sit flush — use a countersunk screw instead.
Custom manufacturing · Made to drawing
Need a hex head bolts with reduced shank outside the standard range?
Material and finish are usually what drives a special — a grade the standard part is not stocked in, or a coating chosen against a salt-spray figure instead of a default. Made by cold heading or hot forging.
Minimum order from 2,000 pieces; samples within 7 days of drawing approval.
