ASF – Audi Space Frame

ASF consists mainly of closed section extruded sections connected to each other by means of injection molded assemblies. According to Audi, the recyclability is five times that of steel.

The total energy required for production is 152-163 GJ compared to 127 GJ for a similar steel wagon.

Extruded

Basically, they are profiled with a box-shaped profile. The alloys used are unpublished Al-Si alloys with a Si content greater than 0,2% to ensure flowability and precipitation hardening during artificial aging.

sheets

Used for load-bearing panels, slabs, roofs and firewalls, they account for 45% of the structure's weight. Their thickness is 1.7–1.8 times larger than that of steel. The used alloy 5182 in the T4 state (more deformable) with an elastic limit of 140-395 MPa. It can be sustained despite having less than 7% magnesium due to the presence of other alligants.

Cast units

They are used in areas subject to the greatest stress.

They are carried out using a process called VACURAL, which involves injecting liquid aluminum into vacuum molds to obtain:

High quality and uniformity, very low porosity to guarantee high mechanical properties combined with the toughness required for fatigue resistance;

Good weldability required for joining with profiles.

Connection techniques

Several techniques are used:

MIG welding: used for thin sheets and for joining nodes to a profile;

Spot welding: for sheet metal inaccessible with nail pliers;

Stapling: of secondary importance from a structural point of view due to reduced static resistance; used for joining sheets to strengthen extended surfaces;

Riveting: used in bearing elements with an enlarged surface; with the same thickness, it has a resistance of more than 30% compared to welding; it also has the advantage of requiring less energy and does not change the structure of the material.

Structural adhesives: used for fixed glass, in door and bonnet joints (together with screwing), in shock absorber supports (together with riveting and welding).

Assembly

After molding, assembly takes place by robotic welding of the components.

Finishing is carried out by grinding and phosphating with 3 cations (Zn, Ni, Mn), which promotes the adhesion of the cataphoresis layer by dipping.

Painting is carried out in the same way as for steel bodies. Already at this stage, the first artificial aging takes place, which is then completed by an additional heat treatment at 210 ° C for 30 minutes.