Aluminium profiles: series, sizes and system comparison. The practical guide

Aluminium system profiles are extruded metal profiles, usually square or rectangular, with at least one continuous T-slot running along the longitudinal axis. They serve as modular building blocks for load-bearing frame structures in special-purpose machinery, production equipment manufacturing and jig and fixture construction. They are classified geometrically by the grid dimension of their outer dimensions and by the slot width. The defined slot grid allows connectors, accessories and add-on parts to be fastened at any position without welding or drilling. Standardised alloys such as AW 6060 T6 let system profiles combine high static load capacity with low dead weight. They form the flexible standard for industrial structures that can be dismantled and reused.

Fundamentals of modular profile technology

Modular aluminium profiles are based on the modular principle of bolted joining technology. Compared with conventional steel structures, operations such as welding, straightening, deburring and painting are no longer required. Components are joined purely mechanically by bolted connections. The central design feature of the system profile is the continuous longitudinal slot. Every component of the system attaches to this geometry, from T-slot nuts and angle brackets through to hinges and panel elements.

The main advantages over steel structures are:

• Weight saving: The specific density of aluminium is 2.7 g/cm³. Dead weight drops by roughly two thirds compared with steel beams.
• Corrosion resistance: An electrolytically produced anodised layer protects the surface permanently against oxidation and abrasion.
• Dismantling and reuse: Components can be positioned anywhere along the slot, moved or rearranged without damaging the surface.

You will find matching aluminium profiles in the item-compatible I-type for modular frame structures directly in the item-compatible profiles category.

Why aluminium is displacing steel structures

In industrial production equipment, the aluminium profile is displacing conventional structural steel S235 thanks to its favourable strength-to-weight ratio and the elimination of thermal joining processes.

The specific material properties in comparison:

• Dead weight: With a density of 2.7 g/cm³, aluminium weighs around 66 % less than steel (7.85 g/cm³).
• Tensile strength: Artificially aged EN AW 6060 T6 reaches a tensile strength of R_m ≥ 245 N/mm² with a 0.2 % proof stress of R_p0.2 ≥ 195 N/mm².
• Corrosion protection: The anodised layer (E6/EV1) with a coating thickness of 10 to 15 µm offers lasting protection against oxidation without any additional painting.

While steel beams have to be welded, straightened, deburred and coated after cutting, the system profile requires nothing more than the cut and the bolted connection. This saves production time and allows the frame geometry to be modified later.

The key grid dimensions and profile sizes at a glance

The grid dimension defines the outer square dimension of the profile cross-section in millimetres. Rectangular and panel profiles are derived from these basic dimensions.

Sizing in practice: which grid dimension for which project?

• 1. Light cladding and covers: Grid 20 (e.g. 20x20 mm) or grid 30 is suitable for panel-by-panel glazing frames, protective hoods or sensor mounts up to 800 mm of unsupported length.
• 2. Standard machine frames: Grid 40 (40x40 mm) forms the backbone of general production equipment construction. For spans up to 1,500 mm and point loads up to 2,000 N, this size guarantees sufficient bending stiffness.
• 3. Load-bearing frames with dynamic loads: For gantry axes, robot cells or base frames subject to travel forces, rectangular profiles such as 40x80 mm or 45x90 mm should be used. From spans of 2,000 mm upwards, profile cross-sections in grid 80 or 90 prevent inadmissible vibration.

Precisely matching aluminium profiles in the 40x40 mm grid can be found in the range of item-compatible profiles.

Slot 6 or slot 8: which slot width is the right one?

The slot width determines the tightening torque that the bolted connection can transmit and defines which accessories can be used. In practice, slot widths 6 and 8 dominate.

• Slot 6 (standard for grids 20 and 30): Designed for thread sizes M4, M5 and M6. Depending on the T-slot nut, the maximum tightening torque is 4 to 10 Nm. Slot 6 is entirely sufficient for light enclosures, sensor mounts and manual workstations.
• Slot 8 (standard for grid 40): Designed for M6 and M8 bolts. It allows tightening torques of 12 to 25 Nm. Slot 8 is required as soon as shear forces act on angle brackets or dynamic loads have to be carried.

Special cases: slot 5 and slot 10

Slot 5 is used on delicate micro profiles (15x15 mm or 20x20 mm in the I-type) for M3 and M4 bolts. Slot 10 is used in the B-type grid 45 and on heavy-duty profiles in order to accommodate M8 and M10 bolts with tightening torques above 35 Nm.

What happens if the wrong slot is selected:

Choosing the wrong slot leads to incompatibilities. A slot 8 T-slot nut cannot be inserted into a profile with slot 6. Conversely, a slot 6 T-slot nut does not have the necessary guidance in a slot 8; the contact area is too small, which leads to plastic deformation of the profile flank under load.

You will find the matching fastening material for all slot widths in the T-slot nuts category.

System comparison: I-type (item-compatible) vs. B-type (Bosch-compatible)

The two dominant system standards, I-type (based on the item MB modular system) and B-type (based on the Bosch Rexroth MGE system), differ fundamentally in their internal slot geometry. Outer profile dimensions such as 40x40 mm can be identical, while the accessories are mechanically incompatible because the internal dimensions differ.

Slot cross-section geometry in detail:

• I-type (parallel slot): The slot flanks run parallel with a flank inclined slightly outwards. As the bolted connection is tightened, the anodised layer deflects elastically. This flank deflection acts as a mechanical bolt locking device against loosening caused by vibration.
• B-type (tapered slot): Inside, the slot has a bevel angle of around 45 degrees. T-slot nuts (hammer nuts) centre themselves in the slot base as they are turned in, producing a positive and friction-locked fit.

Decision guide: which system for a new design?

For a new design, the main application scenario determines the choice of system:

• Choose the I-type for machine frames, automation cells and frames subject to dynamic loads. Under constant vibration, the elastic deflection of the slot flank offers greater operational reliability without additional bolt locking elements. Here, the 40 mm grid with slot 8 represents the most economical industry standard.
• Choose the B-type for installations in existing plant sections built to the Bosch standard, for safety fencing and for manual workstations where the slot 45 grid (grid dimension 45x45 mm with slot 10) is required.

The range is organised precisely by system: here you will find item-compatible profiles and Bosch-compatible profiles in the B-type.

Switching over and mixed operation: compatibility in practice

Extending existing frame structures with components from maunsystem is a frequent requirement. Mixed operation is entirely possible provided the slot and profile geometry is observed.

Combining with existing item components:
maunsystem I-type profiles match the slot geometries and outer dimensions of the item MB modular system. Existing item T-slot nuts, automatic connectors and accessories fit straight into maunsystem I-type profiles. Profiles with the same grid dimension (e.g. 40x40 mm slot 8) can be built together seamlessly.

Combining with existing Bosch Rexroth components:
maunsystem B-type profiles are compatible with the MGE system from Bosch Rexroth. B-type accessories (e.g. T-slot nuts with guide web or hammer-head bolts for slot 8 and slot 10) can be used in existing Bosch profiles.

The critical point: the accessories
Profile bars of different designs can be joined mechanically using external brackets or end plates. The critical point is the T-slot nuts. A B-type T-slot nut jams in an I-type slot or only makes contact with the flanks at isolated points. Under load this leads to plastic deformation of the anodised layer and to a loss of clamping force.

Precise test procedure for identifying the system on existing equipment:

• 1. Measure the slot width: Determine the slot opening with a vernier caliper (e.g. 6.0 mm, 8.0 mm or 10.0 mm).
• 2. Measure the grid dimension: Measure the outer edge of the profile (e.g. 30x30 mm or 40x40 mm).
• 3. Check the internal slot shape: Shine a light into the slot. Does the slot opening run parallel and flat (I-type) or taper at an angle (B-type)?

Series and wall thicknesses: Standard, Light (L) and Economy (E)

Manufacturers structure their portfolio into specific series, defined by the grid dimension and the slot width.

• item series: Classified as series 5 (slot 5 / grid 20), series 6 (slot 6 / grid 30), series 8 (slot 8 / grid 40) as well as series 10 and 12.
• Bosch Rexroth series: Designated by grid and slot width, for example series 20-6, 30-8, 40-10 or 45-10.

Within the same nominal dimension (e.g. 40x40 mm) there are different wall thickness classes (designs):

Decision matrix: Standard, Light or Economy?

The choice of wall thickness class determines material input, edge stiffness and cost.

When to use which class:

• 1. Economy (E / ultra-light): Used for panel-by-panel covers, safety doors or sensor mounts. The profile acts as a carrier for panel elements. The core hole is not suitable for highly loaded threaded connections.
• 2. Light (L): The standard for manual work tables, shelving structures and assembly frames. The profile offers up to 80 % of the bending stiffness of a standard version with around 25 % weight saving.
• 3. Standard (S / heavy): Mandatory for machine bases, gantries and for all structures with dynamic natural frequencies.

Limits of the design classes:
As soon as threads for end-face fastening are cut directly into the core hole (e.g. M12 for levelling feet), the standard version is required. On L and E profiles the amount of material around the core hole is reduced; the pull-out torque of the thread drops by up to 40 %.

Structural design, load capacity and calculating deflection

Aluminium has a modulus of elasticity of E = 70,000 N/mm². That is exactly one third of the stiffness of structural steel (E = 210,000 N/mm²). With identical geometry, an aluminium beam deflects three times as much under the same load as a steel beam.

Deflection f for a single-span beam on two supports with a central point load is calculated using the formula:

f = (F * L³) / (48 * E * I * 10⁴)

• f: Deflection in mm
• F: Point load in N
• L: Unsupported span in mm
• E: Modulus of elasticity (70,000 N/mm²)
• I: Second moment of area (area moment of inertia) in cm⁴

Practical guide values: maximum load capacity at a permissible deflection of L/500
For quick sizing without lengthy manual calculation, the following table shows the maximum permissible static point load (central) and distributed load at a limited deflection of f = L/500 (the standard value in mechanical engineering).

Note: second moments of area as per the data sheet of the respective maunsystem series. Light and Economy versions have different values.

Note on application: The table values apply to the profile cross-section under purely static load. The connecting elements must be designed separately. Their limit loads are generally well below the load capacity of the profile — an automatic connector, for example, transmits around 4,000 N. Under dynamic load, an additional safety factor of at least S = 1.5 to S = 2.0 must be applied.

Materials science, standards and surface finishing

Structural profiles owe their mechanical properties to the alloy composition and the thermal ageing process. The wrought alloy EN AW 6060 (AlMgSi0.5) or EN AW 6063 is used as standard. Through the T6/T66 heat treatment (solution annealed and artificially aged), the material reaches a minimum tensile strength of R_m ≥ 245 N/mm² and a 0.2 % proof stress of R_p0.2 ≥ 195 N/mm². Manufacturing tolerances for wall thickness, twist and straightness follow the precision standards DIN EN 12020-1 and DIN EN 12020-2. Profile surfaces are anodised to protect them against abrasion and corrosion. The E6/EV1 anodised layer has a coating thickness of 10 to 15 µm.

Connectors and accessories at a glance

The load capacity of a profile frame depends largely on the chosen connection technology. Different connecting elements are used depending on the force path, accessibility and assembly effort.

• T-slot nut (standard, automatic, slide-in): The T-slot nut forms the foundation of fastening technology in the profile slot. Standard T-slot nuts are slid into the slot from the end face. Automatic T-slot nuts can be turned into the slot at any point afterwards and are held in place by a spring-loaded ball. Depending on the thread size (M4 to M8), the load limit is a pull-out force of 2,500 to 6,000 N per T-slot nut. Detailed versions are described in the guide T-slot nuts explained simply.
• Automatic connector: Automatic connectors are screwed directly into the longitudinal slot of two profiles meeting at right angles, with no machining of the profile. As it is tightened, the thread of the connector sleeve cuts itself into the profile slot. This connector is suitable for heavily loaded frames and remains almost invisible from the outside. The tensile load capacity is up to 4,000 N per connection. Further technical details are provided in the article Automatic connectors explained simply.
• Angle bracket: Angle brackets join two profiles at a 90-degree angle via the outside of the slot flanks. They are mounted using bolts and T-slot nuts. Integrated anti-rotation lugs prevent slipping under torsional load. If required, the brackets can be fitted with cover caps. Read more under Angle brackets explained simply.
• Butt connector: Butt connectors are used to extend profile bars end to end over long distances. They are inserted into the core holes or slots of both profile ends and expanded using clamping bolts. This design maintains the alignment accuracy of the beam. Static limit values and installation guidelines are explained in the guide Butt connectors explained simply.
• Cube connector: Cube connectors join two or three profiles along the spatial axes X, Y and Z to form a stable corner connection. They are fastened with countersunk bolts directly into the core holes of the end faces. Cube connectors provide a smooth, rounded corner appearance for guarding and display frames.

You will find matching connecting material for all series in the connecting aluminium profiles category.

Procurement and services for special-purpose machinery

For technical buyers and design engineers, procuring system profiles calls for reliable interfaces and tight tolerances.

• Cutting to size and machining options: maunsystem supplies profile bars cut to the millimetre in accordance with DIN EN 12020-2. The standard cutting tolerance is ±0.5 mm. In addition to square cuts, mitre cuts from 15 to 45 degrees are possible. Mechanical machining options such as end-face bores for automatic connectors, through holes or M8 to M12 threads cut into the core hole are carried out immediately before dispatch.
• CAD data and technical data sheets: For integration into CAD systems (SolidWorks, Inventor, Catia), 3D CAD models in STEP format and 2D drawings in DXF format are available for all profiles and accessories. The geometries contain exact mass and area moments of inertia.
• Sampling, availability and framework agreements: Before series production starts, maunsystem provides sample sections for compatibility testing. Standard profiles held in stock are prepared within 24 to 48 hours of order. For recurring requirements in series machine building, we agree framework contracts with commercial volume pricing and scheduled call-off orders.

Make direct use of our cutting service for aluminium profiles.

Application guide: the right profile for your project

The choice of profile size follows from the specific requirements of the field of application.

• Application 1: industrial machine frame (B2B): Base frames for automated production cells require high stiffness against dynamic excitation. Profile choice: grid 40x40 mm slot 8 (I-type) in the standard version, or 45x45 mm slot 10 (B-type). Connectors: automatic connectors or internal heavy-duty brackets. Special feature: the core holes accept M12 levelling feet for levelling on the floor.
• Application 2: safety enclosure and machine cabin (B2B): Guarding separates the operator from the automation area. Profile choice: grid 30x30 mm slot 6 (I-type/B-type) or 40x40 mm Light. Connectors: cube connectors for flat outer surfaces. Special feature: polycarbonate or mesh panel elements are held directly in the profile slot by cover profiles or clamping strips.
• Application 3: ergonomic workstation system (B2B): Assembly tables must be load-bearing and infinitely height-adjustable. Profile choice: support columns in the rectangular format 45x90 mm slot 10, table frame with a 45x45 mm Light cross-section. Connectors: angle brackets with hand levers for tool-free adjustment. Special feature: integrated cable ducts in the profile slots route compressed air and electrics neatly out of sight.
• Application 4: camper conversion and vehicle construction: In vehicle conversion, minimum dead weight and use of space come first. Profile choice: grid 20x20 mm slot 5/slot 6 for wall units; grid 30x30 mm slot 8 for bed frames and rear pull-outs. Connectors: slide-in T-slot nuts with hexagon socket bolts. Special feature: 40 and 45 profiles are too heavy and over-dimensioned for interiors in motorhomes.

Conclusion

The choice of the right aluminium system profile determines the stability, the dead weight and the cost-effectiveness of every frame structure.

Three key points sum up the choice of system:

• 1. Grid dimension and wall thickness must be matched precisely to the span and the permissible deflection limits.
• 2. Slot width and system type (I-type vs. B-type) determine operational reliability and the choice of matching accessories.
• 3. Bolted connection technology replaces time-consuming welding processes and allows modular changes during ongoing operation.

Find precisely matching system profiles, accessories and accurate cut-to-size services directly in the maunsystem range.

Legal notice on trade marks: the brands mentioned, such as “item” and “Bosch Rexroth”, are used solely to describe compatibility. These are compatible products of the maunsystem brand in accordance with § 23 of the German Trade Mark Act (MarkenG). There is no economic connection to the trade mark owners named.