BMW 7 Series: Bonding Aluminium On Steel

IMPORTANT: Conform with safety regulations

Overview of topics

1. Equipment
2. Preparing the surface
3. Bonding coat
4. Hardening times
5. Subsequent treatment

1.0 Equipment

• Sandpaper
• CLEANING AGENT R1
• NOTES ON ADHESIVE K1
• CARTRIDGE GUN

2.0 Preparation of surface

2.1 Steel surface

• Grind bonding surface with a metallic bright finish for better adhesion.
• Clean bonding surfaces with cleaning agent R1.
• Allow cleaned surfaces to dry for approx. 5 minutes.

  Bonding surfaces must be completely dry.

2.2 Aluminium surface

2.2.1 Procedure for new aluminium component

• Do not grind/sand bonding surfaces.

  Clean bonding surfaces with cleaning agent R1.

• Allow cleaned surfaces to dry for approx. 5 minutes.

  Bonding surfaces must be completely dry.

2.2.2 Procedure for previously bonded aluminium component

• Sand off adhesive residue and layers of paint.
• Clean bonding surfaces with cleaning agent R1.
• Allow cleaned surfaces to dry for approx. 5 minutes.

  Bonding surfaces must be completely dry.

• Flame spray the surface:
• Go over the bonding surfaces slowly with the flame.
• Avoid flaming with the blue part of the flame.
• Condensation water appears on the area that is still uncoated. The condensation water in the line of the flame must evaporate completely.
• Directly after flaming, coat the still hot bonding surfaces (approx. 50ºC) with primer.
• Apply primer:
• Apply primer with a brush, cotton or similar item.
• Allow the coated surfaces to dry for approx. 5 minutes.

3.0 Adhesive application

• Processing temperature of glue cartridge 18ºC - 30ºC.
• Object temperature, vehicle and new parts, min. 15ºC.
• Read the vehicle-specific repair instructions to determine the thickness and positioning of the adhesive bead.
• After applying the adhesive, check whether an adhesive component has emerged at the back of the glue cartridge. If yes, break off the bonding procedure. Clean new part. Use new glue cartridge. Contact national hotline.
• Join components and secure in position.
• Remove excess adhesive. Do not use solvent cleaning agents.

3.1 Bonding in conjunction with repair elements (expanding elements)

• Repair elements are special shaped parts to connect new parts with the body. e.g. Partial replacement of engine support.
• The repair elements will spread when a special bolt is screwed in. The repair elements will thereby connect flush to the corresponding profile shape.
• Ensure there is a sufficient gap between the adhesive and the threads for the expander screws (approx. 10- 15 mm).
• Spread adhesive over the repair element with a spatula up to the height of the ridges.

3.2 Bonding in conjunction with rivets

• Make sure that the blind rivet wrench comes in as little contact with the adhesive as possible.

  There is a risk of damaging the exchangeable head of the rivet wrench due to emerged adhesive.

• The standard punch rivets are always replaced by blind rivets in conjunction with bonding.
• The required strength of the connection is only achieved through a combination of bonding and riveting.

4.0 Hardening times

• Refer to NOTES REGARDING ADHESIVE K1

5.0 Subsequent treatment

• Protect the repair area with cavity sealant.

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