ABR A2 stainless steel dome-head self-drilling screw

ABR A2 Stainless Dome-Head Self-Drilling Screw

ADIT’s stainless steel 304 / A2 dome-head self-drilling screw — drills and threads directly into aluminium profiles 2–4 mm thick in a single action, with approved pull-out and shear load tables for outdoor, coastal and chemical-industry environments.

Stainless steel 304 / A2Self-drilling — single actionAluminium 2–4 mmDome head — PH2 bitPassivation coatingApproved load tables

What is the ABR A2 stainless steel dome-head self-drilling screw?

A stainless steel dome-head self-drilling screw (Stainless Self-Drilling Screw, Dome Head) is an engineered fastening solution that combines a drill point (drill wing) at its tip with a rounded, flat dome profile (Pan Head / Dome Head) at its head — all made of stainless steel. This design lets the screw pierce the base material on its own and thread into it in a single continuous action, with no need for pre-punching or pre-drilling a hole.

ABR A2 is ADIT’s stainless steel dome-head self-drilling screw, made of stainless steel 304 / A2 (SS304) with a passivation coating, designed and approved for direct fastening into aluminium profiles from 2 to 4 mm thick. The low dome head provides a wide bearing area over the connected surface, distributing the load and preventing it from sinking into the material — all without compromising the high corrosion resistance characteristic of stainless steel.

When do you use the ABR A2 stainless self-drilling screw? The ABR A2 stainless self-drilling screw is mainly suited to fastening aluminium profiles in environments that require high corrosion resistance: exterior aluminium cladding, aluminium frames and windows, pergolas, outdoor signage, coastal areas, chemical-industry facilities, and any other application where standard cold galvanizing does not provide sufficient long-term protection.

Please note: ABR A2 is approved and rated for fastening aluminium profiles only. The screw is not intended for, and not approved for, direct drilling into steel profiles. For steel applications, use the standard ABR model (cold galvanized), which includes approved load tables for steel connections. Full details in the FAQ later in this article.

Advantages of the ABR A2 stainless self-drilling screw

Not every stainless self-drilling screw is the same.

Approved technical data: precise pull-out and shear values for every diameter and aluminium profile thickness (enabling safe engineering design).
Stainless steel 304 / A2 with passivation: significantly higher corrosion resistance than a standard cold-galvanized self-drilling screw — suitable for outdoor, coastal, and chemical-industry environments.
Aesthetic and functional dome head: the screw’s low, rounded head (Pan Head) provides maximum bearing area and a presentable appearance, suitable for exposed connections in aluminium cladding and frames.
Direct-fastening technology for aluminium: the screw drills and threads in a single action — no pre-punching, no accessories, and no “dead time” on site.
A range of options: 3 diameters (ST3.5, ST4.2, ST4.8), lengths from 9.5 to 50 mm, PH2 bit — a complete solution for most common aluminium thicknesses.
Support and warranty: designed for contractors and engineers who require engineering backing, load tables, and compliance with strict building regulations.

Approved technical data — connection to aluminium profile

The following data forms the basis for safe structural design of an aluminium connection using a stainless self-drilling screw. All values in the table are in kN per single screw. Please note: the values listed below include the characteristic failure load (Nrk/Vrk), the design load (Nrd/Vrd), and the recommended service load (Nrec/Vrec). For engineering design, an appropriate safety factor must be applied. The designer must also verify the tear resistance of the profile itself.

ST 4.8 — ABR A2 stainless dome-head self-drilling screw — connection to aluminium profile

Load parameter (kN)	Aluminium thickness 2 mm	Aluminium thickness 3 mm	Aluminium thickness 4 mm
Failure load — pull-out (Nrk)	2.9	4.6	6.4
Failure load — shear (Vrk)	3.6	3.6	3.6
Design load — pull-out (Nrd)	1.3	2.1	2.9
Design load — shear (Vrd)	2.7	2.7	2.7
Recommended load — pull-out (Nrec)	1.0	1.5	2.1
Service load — shear (Vrec)	2.0	2.0	2.0

Note: the shear resistance does not account for tearing of the aluminium profile. The designer must check the profile’s tear resistance to determine the final shear resistance. This table applies to the connection of the ABR A2 stainless self-drilling screw to an aluminium profile only — for a steel profile, see the FAQ below.

Geometry and dimensions — ABR A2 stainless self-drilling screw

ADIT’s ABR A2 stainless dome-head self-drilling screw series offers 3 diameters, each suited to a recommended aluminium thickness range and a recommended driving speed:

Screw diameter	Head diameter (dk) mm	Head height (k) mm	Bit	Recommended aluminium thickness (mm)	Drilling speed in stainless steel (rpm)
ST 3.5	6.9	2.6	PH2	0.70 – 2.25	1000 – 1500
ST 4.2	8.2	3.05	PH2	1.75 – 3.00	600 – 1000
ST 4.8	9.5	3.55	PH2	1.75 – 4.40	1000 – 1500

Maximum recommended fastened aluminium thickness — by screw length

This table helps you choose the correct length of stainless self-drilling screw, depending on the combined thickness of all the aluminium layers (the supporting profile + the fastened profile) that must be penetrated:

Screw length (mm)	ST 3.5	ST 4.2	ST 4.8
9.5	2.85	–	–
11	4.2	–	–
13	6.2	4.3	3.7
16	9.2	7.3	5.5
19	12.1	10.3	8.7
22	15.1	13.3	11.7
25	18.1	16.3	14.7
32	–	23.0	21.5
38	–	29.0	27.5
45	–	36.0	34.5
50	–	41.0	39.5

Main part numbers — ABR A2 stainless self-drilling screw

Anchor type	Diameter (mm)	Length (mm)	Part number	Box (units)
ABR A2 3.5×9.5	3.5	9.5	ABRA23509	1000
ABR A2 3.5×13	3.5	13	ABRA23513	1000
ABR A2 3.5×19	3.5	19	ABRA23519	1000
ABR A2 4.2×13	4.2	13	ABRA24213	1000
ABR A2 4.2×16	4.2	16	ABRA24216	1000
ABR A2 4.2×19	4.2	19	ABRA24219	1000
ABR A2 4.2×25	4.2	25	ABRA24225	500
ABR A2 4.8×16	4.8	16	ABRA24816	1000
ABR A2 4.8×19	4.8	19	ABRA24819	500
ABR A2 4.8×25	4.8	25	ABRA24825	500
ABR A2 4.8×32	4.8	32	ABRA24832	500
ABR A2 4.8×38	4.8	38	ABRA24838	500
ABR A2 4.8×50	4.8	50	ABRA24850	500

Quick installation guide — ABR A2 stainless self-drilling screw (for aluminium)

Mark the drilling point: a light tap with a center punch for accurate centering will prevent the screw’s drill point from sliding at the start of rotation.
Prepare the correct driver: use a driver at the rotation speed (rpm) that matches the screw diameter per the table above. Unlike carbon steel, stainless steel is sensitive to friction — too high a speed can cause galling and break the drill point.
Drive perpendicular to the profile: hold the driver at 90 degrees to the material with steady, continuous pressure and no interruptions. Driving at an angle or with intermittent pressure causes increased friction and a weak, damaged connection.
Stop when the dome head seats: when the screw’s dome head seats against the aluminium surface — stop in a controlled manner. Continuing to drive after seating raises friction and endangers both the screw and the thread formed in the aluminium.

Additional models in the ADIT catalog for aluminium and steel connections

ABR: dome-head self-drilling screw (Pan Head / Dome Head) made of carbon steel with cold galvanizing, PH bit. Unlike ABR A2, this model is approved and rated for fastening steel profiles as well as aluminium profiles.
ABR A2: the model featured in this article — stainless steel dome-head self-drilling screw made of stainless steel 304 / SS A2 with a passivation coating, approved and rated for fastening aluminium profiles only, for outdoor, coastal, and chemical-industry environments.
ABP: countersunk (conical) head self-drilling screw (Counter-Sink) — cold galvanized, PH bit. Intended for locations where the screw must sit flush and level with the surface.
ABP-T: countersunk (conical) head self-drilling screw with a Torx bit (TX). Offers superior resistance to bit slippage and a higher tightening torque compared with PH.
PS3 / PSL: extra-long screws for fastening insulated panels (sandwich panels), with an EPDM sealing washer for perfect sealing against rain.

For dome-head models with other bits (Torx, Square), or for stainless models not listed here — we recommend checking availability directly with ADIT’s engineers.

Engineering advice + a quality stainless self-drilling screw = a complete solution

The market is flooded with cheap stainless self-drilling screws from obscure sources, which are usually based on low-grade stainless steel, drill slowly, gall in the middle of the drive, or lose their corrosion resistance within a short time. What sets ADIT Ltd. apart from other suppliers is knowledge and standardization. The company’s engineers are available to assist in calculating and selecting the correct screw diameter, screw length, and stainless steel grade, which saves the costs of field failures and enables standard-compliant, approved structural design.

Frequently asked questions — ABR A2 stainless dome-head self-drilling screw

What is the difference between a stainless self-drilling screw and a standard self-drilling screw (cold galvanized)?

A stainless self-drilling screw is made of stainless steel (Stainless Steel A2 / 304) with a passivation coating, so it is far more resistant to corrosion, rust, and damage from cleaning agents and chlorides. A standard self-drilling screw (like the standard ABR) is made of carbon steel with a cold-galvanized coating, which suits protected indoor environments but weakens significantly outdoors, near the sea, or in a chemical environment. When in doubt — stainless steel is the safe choice for the long term.

Is the ABR A2 stainless self-drilling screw suitable for direct drilling into a steel profile?

No. The ABR A2 stainless dome-head self-drilling screw is approved and rated, per ADIT’s official load tables, for direct connection and fastening into aluminium profiles only, 2–4 mm thick. It must not be used for self-drilling into a steel profile — both because the drill-point geometry is tailored to aluminium and because there are no approved load figures for steel for this model. For steel applications, use the standard ABR model (cold galvanized), which includes approved load tables for connecting steel 2–5 mm thick.

What is the difference between A2 (304) and A4 (316) stainless steel in a self-drilling screw?

A2 (304) stainless steel, from which ABR A2 is made, offers very good corrosion resistance for most outdoor environments, aluminium cladding, and pergolas. A4 (316) stainless steel contains added molybdenum and provides even higher resistance to chlorides, and is intended for especially aggressive environments such as desalination plants, direct seawater pools, or harsh chemical industry. For most aluminium applications in construction and outdoors, A2 is the recommended and most economical solution.

Does a stainless self-drilling screw heat up and gall during driving? How is this avoided?

Yes, this is a known phenomenon in stainless screws called galling — high friction between two similar metals that causes the screw to seize within the thread and sometimes break. To prevent it: drive at a lower RPM than recommended for standard steel, apply steady, perpendicular pressure, avoid stops and fresh restarts within the same drive, and stop immediately when the dome head seats against the surface.

Why does a stainless self-drilling screw need to be driven at a slower speed (RPM) than a standard steel screw?

Stainless steel heats up more easily than carbon steel during friction, and the heat generated at a high rate raises the risk of galling and breaking the drill point. That is why ABR A2 is designed to work at controlled speeds: 1000–1500 rpm for diameters ST3.5 and ST4.8, and 600–1000 rpm for diameter ST4.2.

Is there galvanic corrosion when driving a stainless self-drilling screw into an aluminium profile?

There is a moderate galvanic potential between stainless steel and aluminium, since the two metals are a certain distance apart in the galvanic series. However, the risk is much lower than the severe galvanic corrosion caused by using a standard carbon steel screw in aluminium. The passivation coating on ABR A2 reduces the risk even further, which is why it is the standard, accepted solution in the industry for fastening aluminium profiles in outdoor and coastal environments.

How do you choose the correct ABR A2 stainless self-drilling screw diameter and length?

The diameter is chosen according to the combined thickness of all the aluminium layers that must be penetrated: ST3.5 suits a total thickness of 0.70–2.25 mm, ST4.2 suits 1.75–3.00 mm, and ST4.8 suits 1.75–4.40 mm. The length is chosen so that it engages enough thread in the supporting profile — you can use the “Maximum fastened aluminium thickness” table above to match the screw length to the thickness of the fastened layers.

What is the difference between Nrd (design load) and the characteristic failure load (Nrk) in a stainless self-drilling screw?

The characteristic failure load (Nrk) is the figure at which the screw or profile collapses in destructive laboratory tests. The design load (Nrd) is the value after dividing by a safety factor, and Nrec is the recommended long-term service load. You must not design a project according to the failure load! ADIT provides engineers with all the data needed to perform the correct calculation.

Can an ABR A2 stainless self-drilling screw be removed and re-driven into the same hole?

The screw can be removed and the connection released, but it is not recommended to drive a new screw into the same hole. The first drive slightly damages the thread formed in the aluminium, and re-driving may significantly reduce the pull-out resistance. In such cases it is better to move to a larger screw diameter or to place the new screw a short distance from the old hole.

Is the ABR A2 stainless self-drilling screw magnetic?

Austenitic stainless steel of type 304 / A2, from which ABR A2 is made, is generally non-magnetic or very weakly magnetic, unlike standard carbon steel screws that respond strongly to a magnet. This property is sometimes used for a quick field check of the screw’s material identity, but it is not a substitute for checking the part number and obtaining qualified engineering advice.

Planning an aluminium façade, cladding or pergola project? Tell us the profile thickness and load — our engineers will select the right ABR A2 diameter and length and send you the approved load tables.

Talk to our engineers