Note On Working On Aluminum Components And Vehicles - Ah60.00-P-0034-01LW
Model 205, 206, 213, 238, 253, 293
The following points must be observed when working on aluminum components and aluminum bodies:
Information on body workbay
Separate workplaces are required for work on vehicles with aluminum components. Information on this is available in the WIS/EPC under "Special tools"/"Workshop equipment".
Information on dent removal
On aluminum parts, planishing is possible only up to a certain deformation depth.
Comprehensive dent removal work can be accomplished only under the effect of heat. In the event of higher deformation, it is necessary to replace the damaged parts.
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 remove the dents by pressing 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.
Information on drawing in
When drawing in, the aluminum plate is first heated with a neutral welding flame to approx. 150 °C to 450 °C and cooled down again at specific points at the draw-in 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:
- The aluminum surface must be cleaned. Do not burn any contamination into the surface.
- The point to be repaired must be heated up. Thermal expansion within the area to be repaired must be limited.
Information 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 change color accordingly after certain temperatures are exceeded.
- Using an infrared thermometer or pyrometer. Observe manufacturers' specification.
- With a soft wooden wedge (e.g. spruce, willow). Heat up the point to be repaired. Then wipe across the heated point with the soft wooden wedge using 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
A soft wooden wedge that has not been carbonized must be used. Otherwise there is a risk that the temperature display may be incorrect, and the aluminum may be stripped out during restraightening.
Information on separating bonded joints
Before separating bonded joints (e.g. flange connections) they have to be heated first. The maximum permissible temperature is 180 °C. The ideal temperature for releasing a flange connection, e.g. using a chisel, is approx. 100 °C to 120 °C.
Notes on separating bolted connections (flow-hole bolted connections)
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.
Notes on separating punch rivet joints and creating flow formed rivet joints
Only tools approved by Daimler AG may be used.
Information on this is available in the WIS/EPC under "Special tools"/"Workshop equipment".
Observe manufacturers' specification.
Punch rivet joints, accessible on one side, must be bored out, milled-off or ground open.
It must be ensured that any chips and grinding residue are removed immediately.
Otherwise contact corrosion may occur.
Information on separating impact-nail connections
Impact nails are always replaced by blind rivets for repair work. To separate impact nail connections, the heads of the impact nails have to be ground down.
If the same position is used for making the joint with blind rivets, then care must be taken to ensure that the connecting flange is not damaged when grinding down the nail heads. Any impact nail residue in the body must be removed using a suitable punch.
All debris from impact nails remaining in body cavities must be removed.
Notes on various body materials
Shown on model 205.0
Shown on model 205.0
Information on damage diagnosis
The results from the accident diagnosis based on the corresponding documentation must be used for damage diagnosis.
The respective component must always be replaced in the event of any cracks, folds or deformation.
Otherwise the required minimum strength of the structural components is not ensured.
Exception for deformation:
The connecting flange for the front module carrier (D) on the suspension strut tower (C) can be restraightened to a certain degree. When the connecting flange for the front module carrier (D) is restraightened, the permissible tolerances according to the specified values of the respective model series must be observed. Information on this is available in the WIS under "Forms".
Notes on straightening and restraightening
Restraightening in structural areas is generally prohibited. The only exception hereto is the connecting flange for the front module carrier (D).
The following procedure is to be observed for restraightening:
- The deviation of the measuring point (5) may not be greater than 10 mm, otherwise the suspension strut tower must be replaced. The approved straightening systems from Daimler AG must be used for diagnosis. The following straightening systems are available:
- Measuring system
- Straightening bench
- Welding device
- Straightedge and measuring rod
- Restraightening of connecting flange for the front module carrier (D) only for deformation in Z-direction.
The respective component must always be replaced in the event of any cracks, folds or deformation (exception).
Otherwise the required minimum strength of the structural components is not ensured.
When restraightening the connecting flange for the front module carrier (D) the permissible tolerances must be observed.