ADIT AUTO Heavy-Steel Self-Drilling Screw

ADIT AUTO Self-Drilling Screw

Structural self-drilling screw for particularly thick steel — a long No. 5 drill point that pierces, threads and forms a nut thread in structural steel from 4 mm up to 12 mm in one continuous action, with no pre-drilling.

Structural steel up to 12 mmNo. 5 long drill pointNo pre-drilling requiredCertified pull-out & shear valuesBi-metal version (BAUTO)Heat-treated hardened steel

The Adit self-drilling screw family

Choose the right self-drilling screw for your steel thickness, head type and environment.

AUTO / BAUTOStructural · No. 5 point · steel 4–12 mm · bi-metal option ABE / ABEIHex head with washer · galvanized or 304SS stainless BIE / BIE A4Bi-metal · direct drilling in stainless & hard steel PS3 / PSLExtra-long · sandwich panels · wide EPDM washer ABP / ABRCountersunk & round heads · flush aesthetic finish RSZ / RS A2Small lens head · fine metalwork & flush seams

Approved technical data — fastening to structural steel profiles

Values are the engineering basis for designing safe structural connections. All table values are in kN per single screw.

Please note: the values below are characteristic failure loads (Nrk/Vrk). For engineering design, apply appropriate safety factors to obtain the allowable service load, and verify the profile’s tear-out capacity.

ADIT AUTO ST 5.5 — fastening to a thick steel profile

Characteristic failure-load parameter (kN)	Steel thickness 5 mm	Steel thickness 8 mm	Steel thickness 12 mm
Failure load — pull-out (Nrk)	11.2	14.8	15.5
Failure load — shear (Vrk)	8.4	8.4	8.4

ADIT AUTO ST 6.3 — fastening to a thick steel profile (the heavy-duty diameter)

Characteristic failure-load parameter (kN)	Steel thickness 6 mm	Steel thickness 10 mm	Steel thickness 12 mm
Failure load — pull-out (Nrk)	14.1	18.9	19.6
Failure load — shear (Vrk)	11.5	11.5	11.5

Geometry and dimensions — the ADIT AUTO series

Screw diameter	Steel thickness range (mm)	Drill point length Z (mm)	Recommended drilling speed (rpm)	Maximum installation torque (Nm)
ADIT AUTO ST 5.5	4.00 – 12.00	14.0	1000 – 1500	13.0
ADIT AUTO ST 6.3	4.00 – 12.00	15.0	800 – 1200	20.0

Proven in the field — selected projects in Israel

The ADIT AUTO steel self-drilling screw is installed in demanding structural-steel projects.

Bermuda Island Airport

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What is the ADIT AUTO heavy-steel self-drilling screw? A full explanation

The steel self-drilling screw from the ADIT AUTO series (known in the construction industry as a self-drilling screw for thick steel or a structural self-drilling screw) is an advanced engineering solution designed for direct fastening to particularly heavy and thick steel profiles. Its unique feature is a long, reinforced drill point (Drill Point #5) that lets it pierce structural steel up to 12 mm thick, thread itself and form a perfect nut thread in a single, fast, continuous action — with no need for pre-drilling.

While every standard self-drilling screw is limited to thin plates or light profiles, the ADIT AUTO steel self-drilling screw completely eliminates the need for expensive external drill bits, prevents drill-bit breakage on site, and cuts structural work time by tens of percent. The direct result is a low installation cost and fast, safe and precise engineering execution.

When do you use a self-drilling screw for thick steel?

The ADIT AUTO series is designed for demanding applications such as: fastening to hot-rolled steel profiles (like IPE and HEB beams and UNP channels), installing heavy structures, industrial steel frames, fastening insulated panels to thick profiles, and building large-span sheds and steel structures.

Advantages of the ADIT AUTO steel self-drilling screw — engineering power up to 12 mm

Exceptional drilling capacity: an extra-long No. 5 drill point designed to penetrate structural steel from 4 mm up to 12 mm thick effortlessly.
Approved structural values: detailed load tables for pull-out and shear values that let designers and structural engineers perform safe, approved static calculations.
Reinforced steel and durable coating: the screws are manufactured from the highest-quality heat-treated steel with a protective coating that prevents failure, stripping or breakage while penetrating the profile.
Available in a bi-metal version (BAUTO): a perfect solution combining a stainless-steel body for maximum corrosion resistance with a hard carbon-steel drill tip for direct drilling.
Complete field-work efficiency: eliminating the pre-drilling stage, reducing wear on mechanical tools and zero “downtime” on construction sites.

Correct installation guide for self-drilling screws in thick steel (12 mm)

Accurate centering — it is recommended to make a light mark with a center punch at the fastening point. This prevents the screw’s long drill point from “dancing” or sliding across the structural profile when starting.
Adjusting the driver speed (RPM) — drilling in 12 mm thick steel requires working at a steady, moderate speed in line with the technical table. Too high a speed will overheat the drill point, cause it to lose its hardness and burn the screw tip.
Maintaining a 90-degree angle — hold the tool perfectly perpendicular to the steel surface. Applying pressure at an angle will break the drilling wings and seriously harm the quality of the thread being formed.
Controlling the seating torque — as soon as the screw head or the EPDM sealing washer seats against the surface, stop the driver immediately. Applying excess torque (especially with powerful impact drivers) can shear the screw head or destroy the internal thread cut into the profile.

Engineering support, standards and uncompromising quality

The construction market is saturated with cheap, unregulated products labeled as self-drilling or steel-drilling screws that in practice suffer from frequent breakage, slow drilling rates or rapid rusting that leads to serious structural failure.

ADIT Ltd. offers you engineering expertise, complete technical documentation and certified load tables. The company’s engineers are available to provide professional guidance, match the exact screw diameter and length to your project, and ensure a code-compliant, safe and durable connection solution for years to come.

Frequently asked questions — heavy-steel self-drilling screws

What is an ADIT AUTO steel self-drilling screw, and what sets it apart from a regular self-drilling screw?

A standard self-drilling screw (like the ABE model) is designed for light, thin steel profiles, usually only up to 4-5 mm thick. By contrast, the ADIT AUTO steel self-drilling screw is fitted with a long, special “No. 5” drill point that lets it drill directly and fasten elements to very thick, massive structural steel up to 12 mm thick, with no need to prepare a pilot hole in advance.

Why is the drill-point length (dimension Z) so critical when working with 12 mm thick steel?

The drill-point length (the smooth, thread-free part at the tip of the screw) must always be longer than the total thickness of the steel being drilled. If the screw’s thread starts entering the steel before the drill point has fully pierced through the other side, the screw will lock, seize and even shear off immediately. In the ADIT AUTO series the drill-point length is precisely matched and reaches 14-15 mm to ensure clean, complete drilling before threading begins in 12 mm thick steel.

What is the difference between the AUTO steel self-drilling screw and the BAUTO model?

The regular AUTO model is made from high-quality, reinforced carbon steel with a cold-galvanized coating, and is intended mainly for indoor applications or areas protected from moisture. The BAUTO model is a bi-metal screw: the body and head are made of rigid stainless steel that is fully resistant to corrosion (rust) and weather, while the tip and drill point are made of sharp carbon steel laser-welded on. The BAUTO enables direct drilling of 12 mm thick steel in harsh outdoor applications without compromising long-term rust protection.

What is the essential difference between a self-drilling screw (for steel) and a self-tapping screw?

A self-drilling screw for steel has a drill point at its tip and performs both actions together: it drills a pilot hole and immediately afterward forms the thread. A self-tapping screw, by contrast, cannot drill a hole by itself; it can only cut and form the thread inside a hole that was prepared for it in advance using a separate external drill bit of the matching diameter.

What working speeds (RPM) should be used when installing a heavy-steel self-drilling screw?

For self-drilling screws with diameters of 5.5 mm and 6.3 mm intended for thick steel, work at moderate speeds of 800 to 1500 RPM, depending on the diameter and type of steel. Too high a speed (like an unlimited regular driver) will burn and destroy the screw’s drill tip, while too low a speed will not generate the cutting force required for structural steel.

Can a regular steel self-drilling screw be used inside aluminum structures?

Using a regular galvanized steel screw in an aluminum profile exposed to moisture or outdoor conditions will cause the destructive phenomenon of galvanic corrosion (a chemical reaction between the different metals), which will disintegrate the aluminum around the screw and lead to connection failure. To fasten aluminum components safely, you must use stainless-steel self-drilling screws, such as the ABEI series.

What is the difference between the technical value Nrk and the value Nrd that appears in engineering specifications?

The Nrk value (characteristic failure load) represents the absolute physical collapse point of the screw or connection as measured in destructive laboratory testing. The Nrd value (safe design load), on the other hand, is the official figure the engineer uses for the actual structural calculation. The design value is obtained by dividing the failure load (Nrk) by strict safety factors in accordance with the relevant building codes, in order to ensure a full safety margin in the field.

Can the same steel self-drilling screw or the same drilled hole be reused?

Reuse is strongly not recommended. During the initial penetration into the thick steel, the drill point and thread undergo some mechanical wear that reduces their effectiveness. In addition, re-threading into a hole that has already been cut can seriously harm the thread’s grip quality and pull-out capacity (due to “stripping” the profile). If a screw is removed, it is recommended to replace it with a completely new screw and place it at a new drilling point a safe distance from the old hole.

Fastening to thick structural steel? Tell us the profile thickness, load and diameter — our engineers will match the exact AUTO screw and send you the certified load tables.

Talk to our engineers