Note on working on aluminum components and vehicles - AH60.00-P-0034-01LF
MODEL 217, 222
The following points must be observed when working on aluminum components and vehicle bodies:
- Notes on body workbay
- Notes on dent removal
- Notes on drawing in
- Notes on temperature control
- Notes on separation of bonded joints
- Notes on unfastening bolted connections (flow-hole bolted connections)
- Notes on separating punch rivet joints and creating flow formed rivet joints
- Notes on various body materials
- Note on damage diagnosis
- Notes on straightening and restraightening
- Notes on accident repairs
Notes on body workbay
Separate workplaces are required for work on vehicles with aluminum components. Information on this is available in GOTIS in "Body and aluminum workbay".
Notes on dent removal
On aluminum parts, it is possible to remove dents 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.
Notes on drawing 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:
- 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.
Notes 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 should be used.
Otherwise there is a risk that the temperature display may be incorrect, and the aluminum may be stripped out during restraightening.
Notes on separation of 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 detaching a flanged connection, e.g. using a chisel, is approx. 100 °C to 120 °C.
Notes on unfastening bolted connections (flow-hole bolted connections)
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.
Notes on separating punch rivet joints and creating flow formed rivet joints
Only tools approved by Daimler AG may be used.
The application for connections accessible on both sides is stored in GOTIS under "Blind rivet/self-piercing rivet technology".
Observe manufacturers' specification.
Riveted joints accessible on one side must be bore out, milled-off or ground open.
It must be ensured that any chips and grinding residue are removed immediately.
Otherwise contact corrosion may occur.
Notes on various body materials
Shown on MODEL 222
Shown on MODEL 222
Shown on MODEL 217
Shown on MODEL 217
Note on damage diagnosis
Conduct initial accident diagnosis (See "Conducing initial accident diagnosis" document).
If cracks, folds and/or deformation (exception) are present, always replace corresponding components.
Otherwise the required minimum strength of the structural components is not ensured.
Exception for deformation:
Restraightening of the longitudinal member (E) (Aluminum extruded parts) is only partly possible.
When restraightening the front longitudinal member (E) the permissible tolerances must be observed (see Checklist for damage diagnosis in event of accident, form FG 60).
Notes on straightening and restraightening
Restraightening in structural areas is generally prohibited. Exception hereto is only the front longitudinal member (E).
The following procedure is to be observed for restraightening:
- Any deviation to measuring points (11 and 12) may not be greater than 10 mm in the Y-direction, otherwise the "longitudinal member aluminum extrusion press part" E component must be replaced. The diagnosis and measuring systems recommended in GOTIS must be used for the diagnosis (See Checklist for damage diagnosis in event of accident form).
- Restraightening must always be conducted on a straightening system approved by Daimler AG, with the specific pulling device for BR222 and BR217 from the special tool kit (see Special tools).
The front longitudinal member (E) may only be restraightened when deformation is in the Y-direction.
When restraightening the front longitudinal member (E) the permissible tolerances must be observed (see Checklist for damage diagnosis in event of accident, form FG 60).
Notes on accident repairs
Accident repair is subdivided into 2 stages:
- Repair stage 2 (bonded and riveted parts)
- Repair stage 3+ (welded structural parts)
Special qualification training is required for repair stage 3+ on vehicles with aluminum bodies (Aluminum welding qualification certification).
Employees not verified as having participated in special qualification training and have not completed training for body work nor are authorized for such may not perform any work on vehicles in repair stage 3+.
Information on the qualification measures is available through the responsible Market Performance Center (MPC).
Shown on MODEL 222