Aluminum Components And Vehicles Notes- Ah60.00-P-0034-01RG
Model 190, 223
Observe following notes when working on aluminum components and vehicle bodies:
- Note on repair stages
- Note on body materials
- Note on requirements of aluminum workplace
- Note on planishing
- Note on pulling in
- Note on straightening and removing dents
- Note on determining temperature
- Note on separating adhesive bonded joint
- Note on weld joints
Diagram on repair stages on model 223
Diagram of repair stages on model 190.3
Diagram of repair stages on model 190.4
Note on repair stages
Accident repair is subdivided into four stages:
- Repair stage 1 (bolted components)
- Repair stage 2 (bonded and riveted components)
- Repair stage 3 (welded components)
- Repair stage 3+ (welded structural components)
A special qualification measure (MIG welding of aluminum materials) is required for repair stage 3+ for repair activities on vehicles with aluminum bodies. We recommend training at a local specialist welding institute for repair stage 3 repair activities on vehicles (e.g. side wall paneling).
Individuals may not perform any repair stage 3+ activities on vehicles if they are not verified as having participated in special qualification measures, have not completed special body-specific training or are not authorized.
Information concerning qualification training is available from the responsible MPC.
Diagram on body materials on model 223
Diagram of body materials on model 190.3
Diagram of body materials on model 190.4
Note on body materials
Cast aluminum component parts (A) are extremely resistant to bending and must be replaced.
Aluminum pressings (B) can be reshaped to a limited extent and must be replaced after restraightening.
Aluminum sheet component parts (C) can be reshaped up to a certain deformation depth.
Note on requirements of aluminum workplace
Additional requirements for an aluminum workplace:
- Repairs to aluminum bodies and detachable parts require a separate tool kit which may only be used for working aluminum.
- The workplace must be thoroughly screened against steel/grinding dust and steel swarf from adjacent workshop areas (e.g. with permanent partitions or curtains/mobile partitions).
- Regular cleaning of the workplace must be carried out and documented.
- Existing straightening benches and straightening sets can be used alternately for aluminum and steel provided they are cleaned thoroughly beforehand.
- Tools and facilities for aluminum must be specially labeled.
- Aluminum parts must be protected by a spark protection blanket (anticorrosion protection) if grinding is necessary on steel parts, e.g. steel rivets.
- Machining tools and equipment, e.g. for grinding, cutting and planishing, must not be used alternately on aluminum and steel.
Note on planishing
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, dent removal operations on aluminum sheet (5) should start in the middle of the sheet metal. If possible, attempt 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
When drawing in, the aluminum sheet component part (C) is first heated to approx. 150 to 450°C using a "neutral" welding flame and cooled down again at certain points at the draw-in point. The rapid temperature change causes the surface to contract and the aluminum pressing 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.
Clean aluminum surface thoroughly.
Otherwise, dirt may be baked into the surface.
Thermal expansion within the area to be repaired must be limited.
Note on straightening and removing dents
The reshaping behavior of the aluminum sheet component parts (C) is more problematic than steel. For this reason straightening and reshaping can only be accomplished using heat. Once the temperature for reshaping has been reached (250 up to 300°C), the stresses present under tension are loosened by means of targeted hammer blows. During this, it is important to regularly check the temperature of the repair point because the rebound effect resulting from resilient deformation is significantly higher in aluminum sheet component parts (C) than in sheet steel. Avoid jerky pulling operations due to increased risk of cracking.
An infrared thermometer should be used for determining the temperature.
Aluminum tends to tear out very quickly when notches or crimps are present in the reshaping area.
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.
Note on determining temperature
An infrared thermometer should be used for determining the temperature.
Note on separating adhesive bonded joints
Before separating adhesively bonded connections (e.g. flange connections), they must first be heated with a heat gun . The maximum permissible temperature is 180°C. The ideal temperature for detaching a flange connection, e.g. using a chisel, is approx. 100 to 120°C.
If there is an adhesively bonded connection between several sheet metals, it may be necessary to remove individual sheet metals. If there is an adhesively bonded connection between several sheet metals, ensure that an adhesively bonded connection underneath is not damaged. The upper sheet metal should be heated up as briefly as possible.
Note on weld joints
Only tools and repair materials that are approved by Mercedes-Benz Group AG may be used.
Prepare:
When removing the coating prior to welding, ensure that the aluminum metal removal is as minimal as possible (use suitable grinding material).
Testing:
The weld seam gap must not be greater than 1 mm on aluminum sheet component parts and must be supported with a weld pool backing/duplicator. If necessary, a body weld is used.
Weld:
The welds must be prepared immediately before the welding procedure by cleaning with a stainless-steel brush.
The weld seams must be tacked at the beginning, every 4 cm and at the end on aluminum sheet component parts.
The weld seams must be
welded as a seam weld
.
For repair stage 3 (welded component parts), a welding wire ALSi5 with diameter 1.2 mm is recommended.
For repair stage 3+ (welded structural components) only welding wire ALSi5 with diameter 1.2 mm is permissible.