Note on working on aluminum components and vehicles - AH60.00-P-0034-01N

AH60.00-P-0034-01N	Note on working on aluminum components and vehicles
	000 588 02 39 00 Rivet press tool		WS60.00-P-0010B

Model 190, 197 

Observe following notes when working on aluminum components and vehicle bodies:

• Note on planishing 
• Note on pulling in 
• Note on straightening and removing dents 
• Note on temperature control 
• Note on separating adhesive bonded joint 
• Note on separating bolted connections (flow hole or self-tapping fillister head bolts) 
• Note on installing self-tapping fillister head bolts 
• Notes on separating punch rivet joints and creating solid rivet joints (flow formed rivet joints) 
• Notes on accident repair 
• Note on different body materials 

Note on planishing 

On aluminum parts, it is possible to remove dents up to a certain deformation depth.

In the event of higher deformation, it is necessary to replace the damaged parts. Comprehensive dent removal work can be accomplished only under the effect of heat.

In contrast to sheet steel, the dent removal operations on aluminum plate should be started in the middle of the sheet metal. If possible, an attempt should be made to eliminate the dents by pressing them out. Replace sharp-edged and hard dent removing tools with plastic, wood or aluminum tools.

If stretched too much, e.g. with steel tools, aluminum tends to work-harden (blocking of the displacement motion), which can lead to embrittlement or crack formation.

Note on pulling in 

To draw in, first heat up the aluminum plate with "neutral" welding flame to approx. 150 °C to 450 °C and then allow to cool down punctually at the drawing point. The rapid temperature change causes the surface to contract and the aluminum plate assumes its original shape.

The heated point is flattened because the surrounding colder material expands less, preventing thermal expansion of the heated material. When it cools, the heated, flattened material contracts.

• Observe the following working rules:

• Clean aluminum surface. Do not burn any contamination into the surface.
• The repair point must be hated up. Thermal expansion within the area to be repaired must be limited.

Note on straightening and removing dents 

Restraightening in structural areas is generally prohibited.

It is more difficult to reshape aluminum than steel. For this reason straightening and reshaping can be accomplished using heat. After reaching the temperature for reshaping (250 °C to 300 °C), release tension present by tapping carefully with a hammer. It is necessary to check the temperature of the repair point frequently because the rebound effect resulting from resilient deformation is significantly higher with aluminum than with steel. Avoid jerky pulling operations due to increased risk of cracking.

Aluminum tends to tear out very quickly when notches or crimps are present in the reshaping area.

Use soft wooden wedge or thermal paints to determine temperature on unhardened aluminum alloys. On hardened aluminum alloys it is necessary to determine the temperature using a digital instrument (e.g. infrared thermometer or pyrometer).

It is necessary to ensure that the repair point is cooled quickly to maintain the material properties. This also applies for high force in the area of weld joints. Reshaping also results in hardening, which can be and must be reduced again by heating up to approx. 170 °C to prevent cracking. Aluminum die-cast components are extremely resistant to bending and cannot be reshaped. The components must be replaced. Extruded aluminum sections can be reshaped to a limited extent when heated up properly assuming that they are freely accessible.

Note on temperature control 

The following procedures are available for checking the temperature:

• With thermal paints (e.g. colored pens), applied at a distance of approx. 25 mm from the edge of the heating zone. Observe manufacturers' specification.
• With self-adhesive temperature measuring strips whose measuring fields discolor appropriately after exceeding certain temperatures.
• With infrared thermometer or pyrometer. Observe manufacturers' specification.
  • With soft wooden wedge (e.g. spruce, willow). Heat up the point to be repaired. Then wipe across the heated point with the wooden wedge with medium pressure. The following stripes indicate the specific temperature:
  • Light brown at approx. 350 °C
  • Medium brown at approx. 400 °C
  • Dark brown at approx. 450 °C
  • Black at approx. 500 °C

The wooden wedges used should be charred, otherwise the temperature display is not correct and there is a danger of the aluminum tearing during reshaping.

Note on separating bolted connections (flow hole or self-tapping fillister head bolts) 

Bolted connections that are screwed together in aluminum extruded sections can be removed using an electric screwdriver (e.g. cordless screwdriver).

Bolted connections screwed into cast aluminum components must always be unscrewed by hand.

Flow-hole bolts are always replaced by blind rivets for repair work.

Note on installing self-tapping fillister head bolts 

Before screwing self-tapping fillister head bolts into new components, drill required pilot holes with 3.5 √ mm bit.

Note on separating adhesive bonded joints 

Adhesive bonded joints (e.g. flange connections) must be heated before they are separated. The maximum permissible temperature is 180 °C. The ideal temperature for detaching a flanged connection, e.g. using a chisel, is approx. 100 °C to 120 °C.

Notes on separating punch rivet and solid rivet joints and creating solid rivet joints (flow formed rivet joints) 

Only tools approved by Daimler AG may be used.

The application for connections accessible on both sides is available under TRK riveter for self-piercing riveting.

Punch rivet joints accessible from one side must be drilled or milled out.

Fig 1: Body Repair Stages Representation Schematic (Shown On Model 197)

Courtesy of MERCEDES-BENZ USA

Schematic representation of repair stages shown on model 197 

Notes on accident repair 

Accident repair is subdivided into 4 stages:

• Repair stage 1 (screwed parts)
• Repair stage 2 (glued and riveted parts)
• Repair stage 3 (welded parts)
• Repair stage 3+ (welded structural parts)

Special qualification training is required for repair stages 3 and 3+ on vehicles with aluminum bodies. (MIG welding on aluminum materials)

Employees not verified as having participated in special qualification training, who have not completed special training for body work and who are not authorized for such work, may not perform any work on vehicles in repair stages 3 and 3+.

Fig 2: Identifying Aluminum Stampings, Aluminum Cast Parts And Aluminum Sheet Metal Parts

Courtesy of MERCEDES-BENZ USA

Note on body materials 

1. Aluminum cast parts
2. Aluminum stampings
3. Aluminum sheet metal parts