Audi TT (2007 year). Manual - part 259

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not 
 permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability 
     with respect to the correctness of information in this document. Copyright by AUDI AG.

13

Punch riveting

Punch riveting is one of the principal joining techniques used on the bodyshell of the new Audi TT. This tech-
nique is used for joining aluminium body parts and for joining aluminium body parts to steel body parts.
The process has been in use since launch of the Audi A2. Self piercing rivets with two different diameters and 
lengths are used in the Audi TT. 

Punch riveting process

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Applications of punch riveting

With clinching, the metal sheets to be joined are clamped between a die and a blankholder. The sheets are 
then pushed down into the die by a punch to form an interlocking joint. However, joints produced in this way 
is not as strong as joints produced by punch riveting, for example. 
In the Audi TT, this technology is used on attachments such as doors and lids. Several clinched joints are also 
located in the area of the B-post and rear wheel arch. In this area, aluminium sheets as well as steel and alu-
minium sheets are clinched together.

Applications of clinching

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Clinching process

Clinching

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Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not 
 permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability 
     with respect to the correctness of information in this document. Copyright by AUDI AG.

14

Joining techniques and production processes

MIG welding

The usual techniques of resistance spot welding and, to a lesser extent, metal active gas welding (MAG weld-
ing) are used for joining sheet steel body parts in steel body manufacturing.

Resistance spot welding and MAG welding

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Applications of MIG welding

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Applications of resistance spot welding

Applications of MAG welding

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Resistance spot welding process

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MIG welding process

Aluminium parts have largely been joined by means of metal inert gas welding since the launch of the Audi 
aluminium bodyshell in the Audi A8 (1994) . This technique is principally used to make joints between castings 
and extruded sections, as well as sheet-metal parts.
This joining technique is notable for producing high-strength joints, but it introduces a great deal of heat into 
the joint and has a relatively slow process speed.

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not 
 permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability 
     with respect to the correctness of information in this document. Copyright by AUDI AG.

15

Structural bonding

In certain areas, adhesive bonding is used supplementary to clinched joints and punch riveted joints, solid 
punch riveted joints, Flow Drill screw connections and resistance spot welds. This improves joint strength. 
Adhesive bonding is also used for strengthening of seam joints, e.g. in the rear wheel arch. In other areas of 
the body, adhesive beads are used for sealing and insulation between aluminium and steel sheets, as well as 
for noise reduction.

Structural bonding process in production

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Applications of structural adhesive 

Protected by copyright. Copying for private or commercial purposes, in part or in whole, is not 
 permitted unless authorised by AUDI AG. AUDI AG does not guarantee or accept any liability 
     with respect to the correctness of information in this document. Copyright by AUDI AG.

16

Joining techniques and production processes

New joining technique:  solid punch riveting (Kerb-Konus riveting)

Solid punch riveting or Kerb-Konus riveting involves the use of aluminium or coated stainless steel rivets. In 
contrast to punch riveting, the rivet is punched through both sheets to be joined.
Unlike steel rivets, aluminium solid punch rivets can be reworked mechanically. This is the case with the joint 
between the body side section and the drip moulding. However, the strength of solid punch riveted joints is 
inferior to that of punch riveted joints.

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Micrograph of a solid punch riveted joint

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Solid punch riveting process

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Solid punch riveting process in production

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Applications of solid punch riveting

Information on the repair concept

Aluminium solid punch rivets are used in the C-post drip moulding area, while coated stainless steel solid 
punch rivets are used in the region of the roof frame. Stainless steel rivets must not be drilled out or ground, 
due to the risk of corrosion.