The ULAMEX DIN 912 Allen Bolt is a precision socket head cap screw manufactured from A2 stainless steel (1.4301 / AISI 304), designed for use throughout photovoltaic mounting systems. Its cylindrical head with internal hexagon (Allen key) drive enables secure fastening in confined spaces where standard hex bolts cannot reach — a critical requirement in PV module clamp assemblies and profile-to-bracket connections.
Technical Specifications
| Parameter | Value |
|---|---|
| Standard | DIN 912 / ISO 4762 |
| Material | A2 stainless steel (1.4301 / AISI 304) |
| Head type | Cylindrical (socket head cap screw) |
| Drive | Internal hexagon (Allen key) |
| Thread | M8, full thread |
| Available lengths | 20 / 25 / 30 / 35 / 40 mm |
| Tensile strength | ≥ 700 MPa (property class 70) |
| Proof load | ≥ 450 MPa |
| Allen key size | 6 mm (M8) |
| Head diameter | 13 mm (M8) |
| Head height | 8 mm (M8) |
Installation Guidelines
Insert the DIN 912 bolt through the component to be fastened — typically a grounding plate, threaded plate, or clamp assembly — and into the corresponding threaded hole or nut. Use a 6 mm Allen key (hex wrench) or a compatible socket bit in a torque wrench. The recommended torque for M8 stainless steel bolts in PV applications is 16–20 Nm.
The cylindrical head profile sits flush with or below the surrounding surface, reducing snag risk on cables and allowing adjacent components to be mounted closer together. When fastening grounding plates, ensure the serrated face of the plate contacts the aluminium profile surface before tightening — the bolt tension must be sufficient to penetrate the anodised oxide layer for reliable electrical bonding.
Select the bolt length based on the total stack-up thickness: the bolt should protrude at least two full thread pitches beyond the nut or threaded insert. For standard ULAMEX grounding plate assemblies on 40×40 profiles, M8×25 mm is the most common specification. For thicker stack-ups involving clamp bodies and adapter plates, use M8×30 or M8×35.
Applications
- Grounding plate connections — securing grounding plates to PV mounting rails for equipment bonding and potential equalisation per IEC 62305
- Threaded plate assemblies — fastening threaded inserts into profile channels for module clamp mounting points
- Mid-clamp and end-clamp tightening — where clamp designs use socket head bolts instead of T-bolts for a lower profile
- Bracket-to-profile connections — securing angle brackets and adapters in confined assembly zones
- Carport and canopy structures — structural joints where hex bolt heads would interfere with adjacent members
Material Properties
A2 stainless steel (Werkstoff 1.4301 / AISI 304) is an austenitic chromium-nickel alloy containing approximately 18% chromium and 8% nickel. This composition provides excellent resistance to atmospheric corrosion, making it the standard choice for outdoor PV installations exposed to rain, humidity, and moderate industrial atmospheres. The passive chromium oxide layer self-repairs after surface damage, ensuring long-term corrosion protection without supplementary coatings.
A2 stainless is non-magnetic in the annealed condition and maintains its mechanical properties across a wide temperature range (−40 °C to +80 °C typical for PV environments). It is electrochemically compatible with aluminium profiles — the galvanic potential difference is small enough that corrosion at aluminium-stainless contact points remains negligible in normal atmospheric exposure, particularly when EPDM isolation tapes are used at contact interfaces.
Compatibility
The ULAMEX DIN 912 M8 Allen bolt is the primary fastener for the following ULAMEX PV components:
- Grounding plates — 40×40 mm bonding plates with 8 mm bore for equipment earthing
- Threaded plates — channel-mounted inserts for clamp attachment points
- Mid-clamps and end-clamps — module securing clamps on PV mounting rails
- PV profiles 40×40 and 80×40 — aluminium mounting rails with T-slot channels
Why ULAMEX
ULAMEX is an EN 1090 certified B2B wholesaler supplying the complete PV mounting system — from aluminium profiles and clamps to roof hooks and all fastening hardware. One supplier, one delivery, one invoice — simplifying procurement for installers and distributors across Europe. DIN 912 bolts are available in bulk packaging (100, 250, 500, 1000 pcs) with pallet delivery.
Frequently Asked Questions
Q: What Allen key size do I need for M8 DIN 912 bolts?
M8 DIN 912 socket head cap screws require a 6 mm Allen key (hex wrench). For torque-controlled tightening, use a 6 mm hex socket bit in a calibrated torque wrench set to 16–20 Nm.
Q: What is the difference between DIN 912 and DIN 933 bolts in PV systems?
DIN 912 has a cylindrical head with internal hex drive — ideal for tight spaces and flush-mount applications. DIN 933 has an external hexagon head — faster to tighten with a spanner but requires more clearance around the bolt head. Both are available in A2 stainless steel from ULAMEX.
Q: Which bolt length should I choose?
Select a length where the bolt protrudes at least two full thread pitches beyond the nut. For standard grounding plate assemblies: M8×25. For clamp assemblies with adapter plates: M8×30 or M8×35. For stacked connections: M8×40.
Q: Can I use DIN 912 bolts with ULAMEX T-slot profiles?
DIN 912 bolts are not designed to slide into T-slot channels — that function requires hammer bolts (T-bolts). DIN 912 bolts are used with threaded plates, grounding plates, and pre-drilled components that are already positioned on the profile.
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