Engineering Design · 40×40 section, kg/m, slot

What Is a 4040 Aluminium Profile?

A 4040 aluminium profile is a 40 × 40 mm T-slot section. In the grownparts range it runs 1.05–2.35 kg/m depending on wall thickness, with slot variants across the range (table below).

Envelope: 40 × 40 mm
Mass band: 1.05–2.35 kg/m
Reference price (2026): $2.10–$3.45 / m
Read: 8 minutes

Short answer

4040 is the 40 × 40 mm square envelope — the industrial default in many 40-series frames. Grownparts mass sits at 1.05–2.35 kg/m by wall class. Slot variants use a 10.2 mm groove with an 8 mm mouth (including one-face-only layouts); hardware is typically M6 on 40 × 40 and M8 on related beams, on a 40 mm pitch. Tolerances: EN 755-9 / GB/T 6892, wall ±0.15 mm; 6 m stock cut to drawing to ±0.5 mm. Made to order; small trial lengths from stock offcuts. Lead time: 18–28 days after deposit for mill finish. Reference price (2026): $2.10–$3.45 per metre. Context: weight per metre, T-slot dimensions.

4040 aluminium T-slot profile 40×40 mm — mill-finish aluminium extrusion.

What the numbers mean

“4040” is geometry only: 40 mm by 40 mm. It is not an alloy designation and it does not freeze the slot to one universal cavity.

On this site, 4040 variants centre on a 10.2 mm groove and 8 mm mouth at 40 mm pitch. Some dies open one face only with three solid faces; others slot all faces. Fastener callouts run M6 on 40 × 40 and M8 on related beams. Another supplier’s “4040” may use an 8 mm European mouth or a different core hole — interchange is a hardware measurement, not a name match. Read slot dimensions before substituting brands.

Specification table (by wall thickness)

Fifteen in-range 4040 products collapse into three wall classes for quoting.

Variant	Weight (kg/m)	Slot	Wall	Ix (cm⁰)	Typical use
Light wall	1.05–1.40	10.2 mm groove, 8 mm mouth; M6/M8	Light	per die drawing	Guards, light frames
Standard wall	1.40–1.90	10.2 mm groove, 8 mm mouth; 40 mm pitch	Standard	per die drawing	Machine frames, benches
Heavy wall	1.90–2.35	10.2 mm groove; one-face or multi-slot	Heavy	per die drawing	Stiffer uprights, panel bays

Family mass: 1.05–2.35 kg/m. Mid-wall site reference near 1.55 kg/m pairs with Ix on the order of ~10 cm⁰ — always take Ix from the die drawing and the chart.

What it is typically used for

4040 is the square workhorse for industrial modular frames.

Name the jobs explicitly: machine frames, guards, workbenches, conveyors, light gantries, and panel structures. It is also the usual upright and table member beside a deeper 4080 gantry rail. Catalogue: 40 series aluminium profiles.

Where the limits are

4040 covers many 1 m industrial bays; long, heavily loaded members still want depth or a twin rail.

When spans stretch toward 1.5–2 m under useful load, or when a CNC/plasma gantry beam must stay flat, prefer 4080 on the strong axis, twin 4040, or a mid-post rather than hoping a light 4040 will behave like a beam. Check numbers on max span and load. Weak-axis orientation of any rectangular neighbour is a separate failure mode — 4040 itself is square, so Ix is the same about both axes for a symmetric die.

Supply facts: 6 m stock, cut to drawing ±0.5 mm; wall ±0.15 mm; made to order with small trial offcuts; 18–28 days after deposit for mill finish; reference price $2.10–$3.45 (2026).

RFQ checklist — 4040

Wall class — inside 1.05–2.35 kg/m.
Slot layout — 10.2 mm groove / 8 mm mouth; faces open vs solid.
Hardware — M6 on 40×40, M8 on beams as applicable.
Cut list — ±0.5 mm.
Lead — 18–28 days mill after deposit.

Send wall class, slot faces and cut list for the matching 4040 die quote.

Related on this site

Aluminium profile weight per metre — how this section compares across the range
T-slot dimensions — what the slot number means
Maximum span and load — the load limit in numbers
40 series aluminium profiles — products in this series

Terms used in this article

4040: Nominal 40 × 40 mm T-slot envelope in the 40-series module.
kg/m: Mass per metre; here 1.05–2.35 by wall class.
10.2 mm groove: Groove width on grownparts 4040 variants; mouth typically 8 mm.
EN 755-9: Tolerance base with wall ±0.15 mm on this section.
Ix: Second moment of area from the die drawing for deflection design.

Questions buyers ask

Should I use 4040 or a deeper section for a workbench?

4040 is the default industrial workbench rail for many 1 m bays. Step to 4080 on the strong axis, or twin 4040, when the top is heavy or spans push past about 1.2–1.5 m under load.

Should I use 4040 or a deeper section for a machine frame?

4040 is the usual primary square for compact machine frames. Use 4080 or twin rails when horizontals are long, payloads are high, or deflection limits are tight (L/500).

Should I use 4040 or a deeper section for a robot cell fence?

4040 posts and rails cover most cell fences with doors and cable trays. Deeper sections help only when bays are unusually wide or the fence carries heavy panels and services.

Should I use 4040 or a deeper section for a conveyor frame?

4040 is a solid main-rail choice for many light-to-mid conveyors. Long unsupported bays or heavy rollers often need 4080 oriented for stiffness — see max span.

Should I use 4040 or a deeper section for a cleanroom equipment frame?

Yes for cleanroom benches, cabinets and equipment frames that need M6/M8 hardware and reconfigurable slots. Jump deeper only for tall, heavily loaded walls.

Should I use 4040 or a deeper section for a machine guard?

4040 is widely used for perimeter guards and panel structures. Local light windows can drop to 3030; the primary guard frame usually stays on 4040.

Should I use 4040 or a deeper section for a CNC router gantry?

Prefer a rectangular 4080 (80 mm in the bending plane) for the gantry beam. 4040 remains correct for uprights, tables and light axis covers on the same machine.

Should I use 4040 or a deeper section for a test rig?

4040 is a strong default for production test rigs and durable lab frames. Use 4080 when long actuator rails must stay flat without mid-posts.

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